American Airlines Flight 742 "flight control system" problems [Archive]

Centaurus

8th Mar 2013, 04:36

Jet upset training has been included in the training program of most carriers well before this needless tragedy occurred.

The jet upset training I have witnessed in simulators is nothing more than straight forward recoveries from a mild spiral dive or a mild nose up maybe sixty degrees angle of bank. One well known international airline "teaches" jet upsets (unusual attitudes) in the simulator only to the definition parameters stated in the FCTM which are:

Pitch attitude greater than 25 degrees nose up.
Pitch attitude greater than 10 degrees nose down.
Bank angle greater than 45 degrees.
or, within above parameters but flying at airspeeds inappropriate for the conditions.

So a typical test of competency to recover from an unusual attitude is where the instructor puts the aircraft into a 15 degree nose down spiral dive at 50 degrees angle of bank and tells the student to recover to level flight. After all, those figures meet the defintion of "Upset". Sometimes it is a visual manoeuvre or it may be simulated IMC. Basically PPL stuff before first solo.

Those parameters may define an Upset but they are quite benign and easily recoverable.

aa73

8th Mar 2013, 13:42

I have a hard time understanding why some PPruners here are criticizing the pilots' actions based on passenger reports??

So, because the pax were talking about "big red lights" and what was SUPPOSEDLY said on the PA, and the F/A may have been nervous, we now have the full and accurate report by which to hang the flight crew. I see.

Have we learned nothing?

Kudos to the flight crew for safely handling the situation.

bubbers44

8th Mar 2013, 21:48

I think we all think the pilots did an excellent job of landing the airplane. The reporting is in question.

RobertS975

8th Mar 2013, 22:12

Flight control problems in a MD83 can be very serious, especially if it involves a stripped jackscrew that controls the horizontal stabilizer trim. Remember AS 261 back in January 2000.

Alexander de Meerkat

10th Mar 2013, 23:17

bubbers44 - It is always better to counter arguments by refuting what was said rather than what was not said. No one said 'it is ok for your pilots to lose airspeed and pull up into an 11 degree pitch up attitude at FL350 which we all know will result in a full stall'. I can see you are not an Airbus pilot and therefore have limited grasp of the situation, but the whole point of an Airbus is that normally you cannot stall it. 'Lack of pilot skills', as you describe it, is not simply stick and rudder proficiency, all very good as that is. Operating a large passenger jet like an Airbus requires a whole host of other skills, including a thorough grasp of the failure modes and being able to separate the wood from the trees in a high stress environment - a rare skill in my experience. Unfortunately the aircraft in this case had degraded into a reduced flight law status, which was not recognised by the crew. Furthermore you say that 'at FL350 level flight AOA would be nose attitude'. That statement does not entirely make sense to me, but from what I understand you are saying that if the pitch attitude on the artificial horizon (PFD in Airbus parlance) says 2 deg then you would see that as an accurate readout of AoA. That is absolutely not the case and the crew's misunderstanding of that was ultimately what killed everyone. It is entirely possible to have the pitch attitude around 2-3 degrees and still have an AoA of 20-25 degrees, which was the case here. They got into a stall because they pulled back on the sidestick in a reduced flight mode (Alternate Law in Airbus-speak). That induced a stall (an aural warning went off 75 times in the descent sating, 'Stall, Stall' but they never acknowledged it once). The actual attitude on the horizon was only a few degrees but their AoA was massive - something they never recognised. There were two compouding factors - the RHS First Officer for some reason (overwhelming anxiety?) kept his sidestick deflected fully back throughout the whole experience which was not spotted by the LHS First Officer and it therefore made his inputs largely redundant. The second factor was that they had experienced an erroneous speed indication earlier on one side, due to icing of a pitot probe, that had completely blown their mental understanding of the situation. Combine that with a host of strange warnings they could not process, night time, bad weather, no Captain present to take absolute control clearly and positively - you have a cocktail for catastrophe present. There is absolutely no doubt their training was inadequate, but that is another issue. To simply see them as two idiots who lacked basic flying skills is a gross and unhelpful simplification of the situation. Were they ultimately to blame? Without a doubt. Were there a number of other factors which contributed to a totally recoverable situation? Absolutely.

As an Airbus trainer and examiner (check airman in US-speak), my observation would be that if a genuinely unexpected loss of airspeed takes place (not one everyone is expecting because that is what they are doing in that particular recurrent training cycle) it has about a 50% chance of being recovered by the crew. Many would disagree with that view, but that is my view nonetheless. Crashes are rarely one cause as we know - a whole series of events come together in a particular moment of time which together lead to disaster. Many lessons have already been learnt by Airbus operators about this accident - including the need to have stall training on an aircraft that is not theoretically able to stall! When I did my type rating many years ago we never did stall training. That has now changed dramatically and I believe that the vast majority of Airbus pilots facing the same situation as the AF447 crew would be able to recover the aircraft to safe flight. Sadly, it often takes an accident for the right training to be in place.

bubbers44

10th Mar 2013, 23:53

Maybe you can accept poor airmanship as normal but I can't. Sorry. My friends who flew aircraft were held to a higher standard. Loss of airspeed was not an emergency. We flew attitude and power. No 11 degree pull ups at high altitude because we knew the aircraft couldn't do it. It wasn't very hard to do.

bubbers44

10th Mar 2013, 23:57

By the way I took a pay cut not to have to fly the Airbus because I didn't trust it like I did the Boeing aircraft. I trust my thousands of hours of flight more than an Airbus computerized flight computer.

bubbers44

11th Mar 2013, 00:05

Rereading your post, 2 degrees nose up attitude does mean 2 degrees angle of attack if you are in level flight. They had a perfectly good altimiter so holding level flight was not a problem wasn't it. 2 degrees nose up with level flight would have meant 2 degrees aoa. They needed their captain in the cockpit when the AS went south because only he was competent to handle the aircraft. They obviously were not.

RetiredF4

11th Mar 2013, 13:14

Alexander de Meerkat
.......but from what I understand you are saying that if the pitch attitude on the artificial horizon (PFD in Airbus parlance) says 2 deg then you would see that as an accurate readout of AoA. That is absolutely not the case and the crew's misunderstanding of that was ultimately what killed everyone. It is entirely possible to have the pitch attitude around 2-3 degrees and still have an AoA of 20-25 degrees, which was the case here

How true.

But note, that bubbers 44 is making his statement in relation to level flight (bolding by me)

bubbers44
Rereading your post, 2 degrees nose up attitude does mean 2 degrees angle of attack if you are in level flight

Although there is not an exact match under all conditions (especially dynamic ones like turbulence), it is a usable one and would not have killed them.

But to use that info there is a need for basic understanding what AOA is, what it does and what influences it.

fantom

11th Mar 2013, 13:27

...19.2 units...

Ashling

11th Mar 2013, 14:06

bubbers

There are plenty of examples of commercial pilots being unable to fly the aircraft and/or respond to loss of instrumentation and stalls correctly. Perhaps it is better to question the integrity of the system that places them on the flight deck in the first place.

Way too easy to point the finger at individuals.

bubbers44

11th Mar 2013, 22:12

I have taught aerobatics a lot as a civilian and have done hundreds of hammerhead stalls which requires a 90 degree pitch attitude but still isn't a stall when airspeed approaches zero because the angle of attack is also about zero. The rudder over in the vertical dive allows you to recover with no stall. AOA as we all know is the angle between the aircraft attitude and angle of flight. Level flight means pitch attitude is the same as AOA because the angle of flight is level. Turbulence may change angle of attack but the same rules apply. When AF was in their steep descent angle after their full stall they needed to reference their attitude to the steep descent path to recover but they didn't know how.

Automation has decayed basic piloting skills the last decade and it looks like this is the future unfortunately.

bubbers44

12th Mar 2013, 01:53

To the airbus instructor. Have fun with your rules. I will stick with Boeing because I trust Boeing and the rules are always the same. Fly the fricken airplane. Be a pilot. Automation isn't required.

bubbers44

12th Mar 2013, 02:03

99 percent of us Boeing pilots could recover from UAS by the way. Why can't you do more than 50 percent? Automation dependency?

misd-agin

13th Mar 2013, 15:03

99%? Ask the CKA at the Flight Academy. You'll be interested to hear their actual observations vs. uninformed opinions.

And the rules are not always the same on Boeing. 777 and 787 anyone?

bubbers44

13th Mar 2013, 16:42

bubbers44

13th Mar 2013, 16:54

I think I know who you are talking about. Our check airmen in the sims were jealous because they couldn't be real airline pilots, just instructors so tried to put us down to boost their egos. We didn't get to go into a sim that couldn't crash and spend your life with no chance of ever getting violated or explaining why you did anything. We did.

PBY

13th Mar 2013, 17:32

I think that it is not a coincidance that AF447 crashed. It is the fruit of Airbus training. Airbus always used to say, that captain does not need to be a good pilot, but must be a good manager. By the way I am a airbus instructor. But what I see in the sim and on the line is mind-boggling. Such a basic inability to fly the aircraft. No clue about pitch and power and how to set it. By the way, airbus is a good airplane. But the training is a disaster. It has always been like that. Now airbus in its infinite wisdom removed the pitch and power setting for 3 degree glide slope from the manuals. Because now we have magic. Below level 250 we put all the ADRs off and we have back up speed scale. They have just forgot a small detail. If angle of atack indicator gets stuck, it is not going to work and basic pitch and power would be helpful. But Airbus flight training department always need people to get killed before they come up with changes.
Another great idea in the airbus QRH is how to recover from the stall. They are asking to level the wings even before you are out of stall. It is a great entry into the spin. Before I joined the airlines, a good friend, an airline pilot told me, that many airline pilots don't have basic flying skills. I was looking up to airlines. I did not believe it. But now I believe it.

DozyWannabe

13th Mar 2013, 17:55

I think that it is not a coincidance that AF447 crashed. It is the fruit of Airbus training. Airbus always used to say, that captain does not need to be a good pilot, but must be a good manager.

No they didn't. Can you point me to where you read that?

Now airbus in its infinite wisdom removed the pitch and power setting for 3 degree glide slope from the manuals. Because now we have magic. Below level 250 we put all the ADRs off and we have back up speed scale.

Are you sure? BUSS is an optional fit, so it's not going to apply to the whole fleet, plus it won't address the issue above FL250. Pitch and power settings won't have disappeared from the FCOM - IMO they should be a memory item anyway.

Another great idea in the airbus QRH is how to recover from the stall. They are asking to level the wings even before you are out of stall. It is a great entry into the spin.

Are they asking to level the wings, or are they saying not to exceed a certain bank angle? I suspect the intent is to avoid a spiral dive.

bubbers44

13th Mar 2013, 21:07

KBPsen

13th Mar 2013, 21:19

I have always found that people who think there is a simple explanation to anything haven't actually thought much about anything.

No offense bubbers44, but you strike me as someone who, despite having an opinion on most things, haven't actually thought much about anything. Reality is always complex and needs to be treated as such.

bubbers44

13th Mar 2013, 22:13

So in your opinion it is ok to have two qualified totally checked out international pilots that can't handily an airbus?

KBPsen

13th Mar 2013, 22:28

That is neither the question nor the issue. If you think it is you have understood little.

AF447 has been debated exhaustible but you seem to revisit issues that everyone have resolved a long time ago. Such as 1+1=2.

bubbers44

13th Mar 2013, 22:40

Handfly is what I tried to type. The magenta line pilots in my opinion should still be able to do their job if all else fails. We learned from basics so if automation failed we did not care, we just hand flew. AF447 just shows how things are changing.

Lonewolf_50

13th Mar 2013, 22:54

When AF was in their steep descent angle after their full stall they needed to reference their attitude to the steep descent path to recover but they didn't know how.
Or forgot how, due to rust accumulation.
Automation has decayed basic piloting skills the last decade and it looks like this is the future unfortunately.
A topic not just for AF 447 mishap, which is of course in another family of threads. I will suggest that what you meant to say is that it may be the future if no systemic change is made. Am I reading you clearly?

Just out of curiosity: can we get back to AA flight 742, or is that one mostly resolved?

@Dozy 13th Mar 2013 12:32
Are they asking to level the wings, or are they saying not to exceed a certain bank angle? I suspect the intent is to avoid a spiral
dive.
FWIW, a spiral dive is more typically associated with a plane that is flying, not stalling. If your are rotating and stalled, that's usually referred to as a spin. The symptoms can seem very similar, depending on aircraft model and type.

To unstall, as a comment on your remark there, the first step is usually to adjust pitch and follow with wings level. Granted, this may depend on and the maneuver you are involved in at the moment, but as a pretty basic rule, you adjust pitch, which should adjust / reduce AoA, and (either at the same time or slightly after), work for wings level to maximize lift production and thus continue/complete your recovery of controlled flight.

@ PBY:
Another great idea in the airbus QRH is how to recover from the stall. They are asking to level the wings even before you are out of stall. It is a great entry into the spin.
How so? If you approach or enter a stall while in an Angle of bank, you will tend to decrease AoA by returning to wings level, though for my money you will usually get better response by first lowering pitch to reduce AoA (assuming non-inverted flight).

Can you explain what you mean there?

I used to demonstrate slow flight to flight students. Part of the demo was full dirty slow flying at high AoA, and then showing them AoA increase and stall onset brought on by turning the aircraft (increasing AoA). Would it not follow that rolling out of any turn/bank would normally decrease AoA and help prevent/recover from stall?

iceman50

13th Mar 2013, 23:18

PBY

I think you need to go back to school 1. to read properly and 2. to flight school to understand stall recovery properly.

The QRH categorically states as the first action

NOSE DOWN PITCH CONTROL............APPLY
This will reduce angle of attack
Note: In case of lack of pitch down authority, reducing thrust may be necessary

BANK.........................................WINGS LEVEL

bubbers44

14th Mar 2013, 00:01

Lone wolf 50, at least we have found one pilot who understands how airplanes fly. Yes, if you are stalled lower the nose, level the wings and wait for the proper airspeed to pull up without stalling. Hopefully the ground doesn't hit you before you attain proper speed. AF447 couldn't do it with two fully qualified FO's but I bet you could. Good for you.

PBY

14th Mar 2013, 00:59

quote from Dosy:
Are you sure? BUSS is an optional fit, so it's not going to apply to the whole fleet, plus it won't address the issue above FL250. Pitch and power settings won't have disappeared from the FCOM - IMO they should be a memory item anyway.

I am not talking about pitch and power above 250. Of course there is pitch and power settings in Airbus manual. But they have removed potch and power setting for 3 degree glide slope which used to be there until a year ago, when they removed it. Would you be so kind and go to the manual and let us know, if you can find it?
They removed it because now they have BUSS. But if AOA gets stuck, BUSS is not going to work.

quote from Dosy:
Are they asking to level the wings, or are they saying not to exceed a certain bank angle? I suspect the intent is to avoid a spiral dive.

We are talking about stall here, not a spiral dive. But of course, after you unstall the wing, you should level out. The question still remains, should you level the wings BEFORE you unstall the wing? I don't ink so.

quote from Iceman:
PBY

I think you need to go back to school 1. to read properly and 2. to flight school to understand stall recovery properly.

The QRH categorically states as the first action

NOSE DOWN PITCH CONTROL............APPLY
This will reduce angle of attack (my highlighting)
Note: In case of lack of pitch down authority, reducing thrust may be necessary

BANK.........................................WINGS LEVEL

Iceman, read further: after bank...... wings level what does it say?

When out of stall.... increase thrust smoothly

Do you see, you did not continue reading. They tell you first to level the wings and than when out of stall, do something else. Just reducing the angle of attack does not mean you reduced it below the stalling angle.

quote from lonewolf:
How so? If you approach or enter a stall while in an Angle of bank, you will tend to decrease AoA by returning to wings level, though for my money you will usually get better response by first lowering pitch to reduce AoA (assuming non-inverted flight).

I used to teach aerobatics. If you are close to the stall or you are in the stall and you at that moment try to abruptly level the wings, you will increase the angle of attack of the wing with the down aileron. The down deflected aileron will change the relative camber of the wing (sorry forgot the exact english expression here) into a hiher angle of attack. It used to be a fun way to enter a spin or increase the spin rate. I used to do it to show students that you don' have to enter a spin just by kicking a rudder, because they used to tell me they would never kick the rudder. I just oppose the Airbus QRH procedure to level the wings before you are out of stall. You need first unstall the wing before the wing will listen again to your commands with the aileron. Is it so difficult for pilots to understand basic flying concepts these days? By the way the british chief pilot of airbus says exactly the same on his video. First unstall the wing, than level it.

By the way can anybody please explain to me how to use the quote feature in pprune? This is my longest reply I have done in a long time. I do not enjoy sitting by computers. I do too much handflying of airbus every day, to help guys overcome their fear of manual flying. I must say, they usually improve quite fast, when they are exposed to it. Unfortunately some guys get exposed to manual flying the first time, when sh1t hits the fan.
If I don't respond more to this, don't take it personally. As I said, I am not a computer guy. I would rather discuss all this by the beer.

iceman50

14th Mar 2013, 02:45

PBY

You are confusing many things here. The removal of the approach attitude info is only for A/C that have the BUSS fitted and it is part of the ADR / unreliable airspeed checklist, you are now applying a "double" failure of the AOA probes as well!
If one does not know the rough attitude, power setting required for a 3 degree slope then perhaps one should not be in the cockpit. Have you tried the BUSS yet in the simulator, works a treat.

What are you going to do if you stall in the turn at altitude? The second preamble to the stall recovery is to cover for the lack of pitch control and slamming to Toga which could pitch the A/C up into the stall again or being in an high nose attitude situation in the first place. Have you actually tried it in the simulator because it works!

I used to teach aerobatics. If you are close to the stall or you are in the stall and you at that moment try to abruptly level the wings, you will increase the angle of attack of the wing with the down aileron.

My highlighting of your quote above shows the problem, you are wanting or describing to "ABRUPTLY level the wings" BEFORE you have applied pitch to REDUCE the AOA! Incorrect technique.

Perhaps you should also realise that Airbus, Boeing and the other manufacturers agreed this "new" stall recovery procedure. The fact is, it is not new and was taught from day one where I was trained. The thrust coming later is because the minimum height loss was becoming a zero height loss for some trainers and checkers. Which is incorrect and required immediate full power application, which in some instances in large jet A/C can exacerbate the situation or even prevent recovery.

westhawk

14th Mar 2013, 03:11

By the way can anybody please explain to me how to use the quote feature in PPRuNe?

To quote selected text just copy and paste it into the reply box, then highlight the selected text. While it remains highlighted, go to the toolbar at the top of the reply box and press the quote button to wrap quote tags around the selected text.

OR if you want to quote an entire message, along with attribution to the author of the post, press the REPLY button in the lower right hand corner of the post you want to quote. This will take you to the REPLY box where you may then edit or remove parts of the quoted text you don't wish to appear in the quote box of your reply post.

Clear as mud now? :)

Detailed instructions for using v bulletin (the forum software) features are easy to find with an internet search if you feel so inclined. And not really a "computer guy" either. I just try to learn what I need to in order to use the tool effectively. Similar to knowing an airplane and all of it's various tools.

PBY

14th Mar 2013, 03:14

Iceman, I agree with you, that if somebody does not know the pitch and power in the 3 degree glide, one should not be in a cockpit. So now, when you finally agree with me that it is of a paramount importance to know that, the info should be in the cockpit, why Airbus does not provide this vital info in the QRH?
You are talking about double failure. Imagine a single cause. Pitot, static and Aoa iced up or contaminated with a sand during a sandstorm and AOA stuck.
Now you have no BUSS and you fly pitch and power. You have know training, no info on pitch and power from official source (airbus manual). Lawyers will love it, as much as they are sueing the a$$ of airbus training department due to A447 accident.
Thank you also on agreeing with me, that we should first get out of the stall by reducing the angle of attack and than level the wings. The airbus problem in The QRH is a problem of sequence. They do say level the wings before the column when out of stall.
So now when we agree with each other, good night!

Lonewolf_50

14th Mar 2013, 12:59

PBY:

It's a pity you and I aren't talking about the same thing here.
If you are close to the stall or you are in the stall and you at that moment try to abruptly level the wings,
has little to do with the topic of how to handle an A330, but thanks for explaining to me what you meant.

I do appreciate the finer points you make about aircraft flying at the edges of performance, so thanks for that insight. :ok:

sevenstrokeroll

14th Mar 2013, 13:51

bubbers 44 says it all in post # 49.

when I was actively teaching, I made my students learn this the very first lesson.

Momoe

14th Mar 2013, 14:51

Bubbers,
it's not an Airbus or Boeing issue - It's a pilot issue.

Just like you, the AF447 pilots probably trusted the plane which would have flown out of the situation IF the correct control inputs had been applied.

Two qualified pilots plus an experienced captain for some of it, Turkish at AMS, three qualified pilots and again a plane which would have flown out of the situation IF the correct control inputs had been applied.

It's your employers who are making the decision to use the automatics at every opportunity, however, it's the pilot's job to stay one step ahead and take over as appropriate.
This isn't aircraft or manufacturer specific and never has been.

deptrai

14th Mar 2013, 14:59

Then why did the two FO pilots in AF447 fail to control their Airbus? Maybe the Airbus can be flown just like a Boeing but the pilots are not trained to use their manual flying skills like we were. That is the problem. Automation dependency.

this has already been discussed ad nauseam but I'll add to the noise. FO Bonin who was PF, had (recent) glider experience, and I think it might be an oversimplification to say that he was automation dependent. He may not have been able to understand - or believe - what he saw on his instruments though, (particularly as airspeed indication clearly was unreliable, and they were faced with multiple failures as a result of that), and maybe he didn't notice, or misinterpreted the buffeting. Some kind of cognitive confusion, denial, and/or over-saturation with information. He may have reacted to what he though was an overspeed condition. Or it may just have been a knee jerk reaction, based on some gut feeling (which is what most humans do when surprised, in an unusual situation: too much, too quickly, sometimes the wrong thing, and often without proper analysis). This is somewhat speculative, we'll never know exactly what was going on in his mind, but one thing is sure, and here I agree with you regarding "manual flying and training": high altitude stall recovery and unusal attitude recovery training at Air France could have been better. But I don't think this is an A vs B issue.

misd-agin

14th Mar 2013, 15:35

I guess it is 99% of the good pilots I know that would have no problem with UAS. You must be talking about other pilots. What airline do they fly for? What is so hard about holding 2 degrees above the horizon that your pilots can't figure out?

We fly for the same airline. And the percentage was much lower than 99%.

By the way I took a pay cut not to have to fly the Airbus because I didn't trust it like I did the Boeing aircraft.

Because you choose to fly the 757. With your seniority you could have flown the 767 at the same pay. And it was the A300 and not the FBW models.

I think I know who you are talking about. Our check airmen in the sims were jealous because they couldn't be real airline pilots, just instructors so tried to put us down to boost their egos. We didn't get to go into a sim that couldn't crash and spend your life with no chance of ever getting violated or explaining why you did anything. We did.

We have different opinions on the overall quality of our CKA. They're not perfect but as a whole I don't see the jealousy or ego issues to the extent you're describing.

bubbers44

15th Mar 2013, 01:20

I still didn't trust the A300 and the 767 spent too much time doing red eyes so took the easy TGU day trips and slept in my own bed most nights. I only know one pilot that couldn't fly without airspeed. I stick with the 99%. The Sim instructor insisted it was 50%. They weren't always our friends and loved to try to make us look bad because they spent their whole life in a sim, we did it every 9 months.

It has been a very long time since we broke a tail off a Boeing but not that long ago our A300 lost it's tail because of a little wake turbulence and copilot rudder action that was conveniently blamed on the incident by Airbus. As has been reported before that Airbus A300 had delamination of the vertical stabilizer coming out of the factory and was patched but Airbus denies that had anything to do with it. My friend in MIA lost control of their A300 with uncontrollable yaw on final and had to go around. They felt they were going to crash. Something with the yaw damper.

My era of pilot friends all knew how to handfly any airplane well. No need for automation at all except to reduce work load during cruise. Most of the time was spent manually flying on climbs and descents and approaches because it was fun. The new Embry Riddle guys aren't taught that way. They have to do it on their own or do it the Airbus way. I got my final commercial pilot sign off at Ambry Riddle but over 90% was at my local airport. I went straight to a crop dusting job in Minnesota so never became automation dependent.

I don't mean to put the magenta line pilots down but what do you do when all the lights go out? We always had a way out. So should the new pilots.

hikoushi

15th Mar 2013, 02:53

Lest we forget that any airplane can be stalled into the ground from cruise altitude, remember:

West Caribbean Airways Flight 708 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/West_Caribbean_Airways_Flight_708)

...which is applicable to the present discussion due to the nature of the accident, and to the original intent of this thread due to the airplane type. DC-9 variants are some of the most "manual" airplanes out there (about to leave a seat in one for an Airbus, so no prejudice either way here. Will report back after getting used to the new beast).

If the pitch and power setting for a 3 degree final approach is not in the manual (don't have manuals for the airplane yet so couldn't say what's in ours), how about figuring it out the same way you did when you got your instrument rating (assuming that was in the days where GA piston singles did not have PFDs, GPS, and flight directors). Next time you are on final out there somewhere, take a look and write it down. In fact, let me know; I need some sim gouge! ;):8

sevenstrokeroll

15th Mar 2013, 06:26

regarding the carribean md80 crash...wasn't there some thought that the plane was overloaded? Also improper use of anit ice?

anyway...a crash is a crash...and if you stall a plane, regardless of manufacturer and you cannot recover, not only did you screw up by letting the stall happen, but not being able to recover is really not earning your pay.

fruther
I would like to think of Air France as a first class line...and the carribean thing...not so first class.

the Stall is what makes the plane different than just an air going sort of automobile. how did we get to the point where a stall isn't right up there with concerns of safe flying?

bubbers44

15th Mar 2013, 21:05

Us old guys just would love you to have the same basics that we did. We are not better than you by any means. We just had different training. We went from J3's to Cessnas to Piper to Lear Jets to Boeings, to MD80's to biplanes and sailplanes effortlessly because they all flew the same. Some of the planes didn't even have a battery installed. Tailwheels were normal and aerobatic flight was effortless. Beach18's with round motors were what we got our multiengine rating in. Then we got to haul freight at night single pilot IFR and loved it. I guess we were the lucky ones. We loved what we did and grew up during the perfect time to fly when everybody knew how to recover from a stall with ease. We had no one to dispatch us, figured our own fuel load and most of the time didn't have to listen to your captains opinion because you were the captain.

We learned in baby steps as we learned basics first then stuck your nose in a little ice just to see what it was like with an easy way out to clear skies. Most of what we learned was self taught. Read a book and go do it. We got the basic minimum instruction to be legal but 90% was reading.

Occasionally you got in a bit over your head but you learned from it.

Most of us started as flight instructors sometimes learning as much as your students in the beginning.

I am so happy United didn't hire me when I was in college when I went through a mini interview with 100 hrs. back in the mid 60s. So much of this experienced would have been missed.

sevenstrokeroll

15th Mar 2013, 23:20

right on bubbers!

Clandestino

15th Mar 2013, 23:34

It has been a very long time since we broke a tail off a Boeing but not that long ago our A300 lost it's tail because of a little wake turbulence and copilot rudder action that was conveniently blamed on the incident by Airbus. As has been reported before that Airbus A300 had delamination of the vertical stabilizer coming out of the factory and was patched but Airbus denies that had anything to do with it. And there I was, believing that since AA587 happened on American soil, the report that explicitly stated that the fin failed at load exceeding ultimate design one, caused by enormous sideslip, brought on by divergent yaw oscillation, originating in F/Os completely unnecessary and excessive rudder inputs, was authored by National Transportation Safety Board and certainly not Airbus.

Things we learn on PPRuNe...

wasn't there some thought that the plane was overloaded? Also improper use of anit ice? Yes, there were such thoughts. While not completely unfounded, what would be their point exactly?

a crash is a crashNice tautology yet I have to observe that CFIT is not LoC.

.and if you stall a plane, regardless of manufacturer and you cannot recover, not only did you screw up by letting the stall happen, but not being able to recover is really not earning your pay.There are thousands of passenger aeroplanes flying right now that don't meet stall recovery requirements and have been demonstrated in practice to be unrecoverable. How about that?

I would like to think of Air France as a first class lineEveryone is free to think world is flat plate carried around on the back of the really big turtle but it would be very impractical to use navigational methods based on this notion.

how did we get to the point where a stall isn't right up there with concerns of safe flying? By imagining things. In real world, stall is still major concern.

I don't mean to put the magenta line pilots down but what do you do when all the lights go out? If you paid attention just to Avherald, let alone FSF, you would know that overwhelming majority of us flies just fine without all the electronic gizmos when fit hits the shan.

My era of pilot friends all knew how to handfly any airplane well.Sadly, I can't find significant gap anywhere in ASN's list of crashes following loss of control (http://aviation-safety.net/database/dblist.php?Event=REL) that would help me pinpoint the golden age when all pilots knew how to fly.

high altitude stall recovery and unusal attitude recovery training at Air France could have been better.Could be, but no direct benefit would come from it. CVR and FDR records bear no indication that stall was recognized by anyone in the cockpit so no recovery was attempted. Aeroplane's attitude, while excessive for high altitude cruise, was never what is considered to be UA and upset was strictly man-made.

So now, when you finally agree with me that it is of a paramount importance to know that, the info should be in the cockpit, why Airbus does not provide this vital info in the QRH?Because folks who need to know it (we call 'em "pilots"), tend to remember it after first couple of approaches?

They do say level the wings before the column when out of stall. They say something else on the very first page of the manual, which is oft happily disregarded on the PPRuNe.

The QRH categorically states as the first action What's the title of the QRH procedure?

bubbers44

16th Mar 2013, 01:46

Clandestine once again shows his arrogance by saying dozens of pilots are wrong but he is right. He must really be a pleasure to fly with if he is real. I know some pilots on here that I trust and are real, I don't know him. Maybe he is making this all up. How would you know?

Centaurus

16th Mar 2013, 01:50

The QRH categorically states as the first action

NOSE DOWN PITCH CONTROL............APPLY
This will reduce angle of attack
Note: In case of lack of pitch down authority, reducing thrust may be necessary

BANK.........................................WINGS LEVEL

.

The intent is this is done simultaneously; meaning within seconds. Not as a one step - stop to think about it - then at leisure roll wings level. It is common to see flying school instructors teaching that recovery from a wing drop at the stall, is to skid the wings level by using full rudder and only when the wings are level by that crazy method (if you haven't already flicked into a spin in the opposite direction to the original wing drop), dare to use the ailerons. That teaching which has been perpetuated for decades is flawed. I wonder how many airline pilots were taught this crazy method during the ab-initio training to PPL and continue to believe this in jets

Clandestino

16th Mar 2013, 08:43

That teaching which has been perpetuated for decades is flawed. I wonder how many airline pilots were taught this crazy method during the ab-initio training to PPL and continue to believe this in jets Correct, just to add the method might befit basic trainer with powerful rudder, indifferent ailerons and benign stall characteristics but it is indeed thoughtless to assume that this method is universally applicable.

AS to the American Airlines A 300 Crash near KENNEDY Airport, at least one member of the NTSB strongly disagreed with the probably cause. I stand with him.

Member Carol J. Carmody’s Statement, in which Member Richard F. Healing joined:

I support the probable cause language in the original staff draft, which listed
contributing factors as the American Airlines Advanced Aircraft Maneuvering Program
and characteristics of the A300-600 rudder system. I heard no reason either during the
staff presentations, or in the explanation provided by the Vice Chairman in submitting his
substitute, to reverse this order. To diminish the role of the AAMP in the accident is to
downplay the role it played in the pilot’s actions which caused the accident. One of the
undeniable facts of this accident is the pilot’s inappropriate use of rudder. Staff was
unable to find any example of unusual rudder use by the pilot before his AAMP training.
When questioned by a captain for using the rudder in an earlier incident, the first officer
“insisted that the AAMP directed him to use the rudder pedals in that manner.” To elevate
the characteristics of the A300-600 rudder system in the hierarchy of contributing factors
ignores the fact that this system had not been an issue in some 16 million hours of testing
and operator experience—until the AAMP trained pilot flew it. The justification for the
change was that the Board must address the future and, therefore, must give more
attention to the aircraft rudder characteristics. That is what our recommendations are
designed to do, and our recommendations do address the design issues. The probable
cause should reflect accurately what the investigation and the report demonstrate; the
substitute probable cause does not do that.

So you agree that AAMP is bigger culprit than A300 rudder design?

AS to any flying out of the envelope, like being over loaded or flying too high for a particular weight,temp etc, or not using anti ice properly, that is just poor flying.Aeroplane was not structurally overloaded but it was too heavy for the altitude crew tried to reach. AF447, Pinnacle 3701, West Carribean 708 and Pulkovo 612 were crashes primarily stemming from crew's inability to understand aeroplane's performance. All the manual flying skills can't help you to force aeroplane to go where she is just incapable of going.

bubbers44

16th Mar 2013, 21:20

AF447 had no performance problem. They knew they were not able to climb at their weight so elected to not do so. When the autopilot and AT failed with the UAS they pulled back for some reason and stalled causing the crash. We have covered this a dozen times but performance was not the problem, inducing an unnecessary stall was.

Clandestino

20th Mar 2013, 22:15

AF447 had no performance problem.By itself, it did not. If aroplane is too heavy or air is too warm for the altitude you want to fly at, you simply fly lower and that's it.

When the autopilot and AT failed with the UAS they pulled back for some reason and stalled causing the crash.We are not discussing Corsair, Super Stinker, Marganski Swift or Phantom, fine machines that can be flicked but airliners and they can't be. When stable and not very maneuverable aeroplane stalls, it more often than not is performance related i.e. running out of speed. AF447 was no exemption. They tried to pull her where she was just incapable of going. Like 727 at Stony point or 757 at Puerto plata.

Anyway, did the incident we're discussing here happen at all? I can't find anything except ASNwiki and strangely, Avherald lists completely unrelated incident for the registration and date.

bubbers44

20th Mar 2013, 22:32

Yes, we all know that. They were at the right altitude for the temp and weight. Performance was not the problem. Pulling up over 3,000 ft and stalling was the problem. They lost AS, AP and AT, pulled up 11 degrees and stalled for no reason.

aa73

21st Mar 2013, 00:21

The NTSB will issue a ruling in order to protect an aircraft manufacturer before a pilot EVERY TIME. AA587 was no exception.

Had 587 been a Boeing or McD, the accident would never had happened.

And no, I'm not making excuses for the F/O either: yes, it was documented that he made the rudder inputs, based on AA's fighter-oriented AAMP training program back then. But that should have never torn off the tail.

bubbers44

21st Mar 2013, 00:47

AA73, I went through that training and still wouldn't have used aggresive rudder inputs. I would have coordinaed my control response to what was needed. teaching aerobatics for hundreds of hours makes you know how much rudder is needed. Our Airbus had a weak vertical stabilizer and Airbus knew it because it came out of the factory that way. Blaming the FO for rudder inputs got Airbus out cheap. The vertical stab failed right where they put the clamp fix that didn't work.

DozyWannabe

21st Mar 2013, 01:44

Had 587 been a Boeing or McD, the accident would never had happened.

What do you base that assertion on?

...But that should have never torn off the tail.

But that's precisely what *will* happen in a conventional empennage design where the rudder runs the full height of the vertical stab and those inputs are made during that phase of flight. Doesn't matter if we're talking A300, B757, B767 - composite, aluminium or whatever. If you exceed "Ultimate Design Loading", that stab is coming off.

The procedure outlined in the AAMP programme was designed for the DC-9/MD-80 fleet and was only applicable to those types due to the design aspects of the aircraft.

A lot of aspersions were cast about the strength of construction of Airbus types at the time, but the fact is that the A300 is and remains the only commercial airliner type to make a successful landing following a direct hit from a SAM, not to mention the fact that the A320 on the Hudson held together well enough and for long enough to get everyone off safely.

@bubbers44 - That supposedly "weak" vertical stab held on for significantly longer and under significantly more load than it was designed to handle under optimum conditions - how can it therefore be called "weak"?

Capn Bloggs

21st Mar 2013, 09:19

A lot of aspersions were cast about the strength of construction of Airbus types at the time, but the fact is that the A300 is and remains the only commercial airliner type to make a successful landing following a direct hit from a SAM, not to mention the fact that the A320 on the Hudson held together well enough and for long enough to get everyone off safely.

Pure luck; got nothing to do with the strength of Airbus. If that SAM had hit 1m closer to a critical part of the aircraft it would have been a smoking hole in the ground. And I'm sure that a 737 in Sully's hands would have resulted in exactly the same outcome.

Clandestino

21st Mar 2013, 11:32

They lost AS, AP and AT, pulled up 11 degrees and stalled for no reasonExactly. Lack of reason was big culprit in it.

The NTSB will issue a ruling in order to protect an aircraft manufacturer before a pilot EVERY TIME. NTSB never issues rulings. Their findings, conclusions and recommendations are always well supported by thorough analysis, open for everyone to see and check. That many an ignoramus is incapable of understanding what is written yet keeps on harping how it's wrong while giving no coherent and plausible argument is just something we have to live with.

Had 587 been a Boeing or McD, the accident would never had happenedSo, warnings about airframe being capable of breaking in overstress below Va if large and alternating flight control inputs are used, adorning all AOMs, AFMS, FCOMs of western-built transport aeroplaneas are actually superfluous? Of course it wouldn't have happened as it seems that one the pilot that misunderstood AAMP was flying A300 at the time!

AA73, I went through that training and still wouldn't have used aggresive rudder inputs.That's because you understood what you were told.

teaching aerobatics for hundreds of hours makes you know how much rudder is needed.Does it? On transport category aeroplane that gets into moderate bank after hitting the wake it is exactly zilch.

Airbus had a weak vertical stabilizer and Airbus knew it because it came out of the factory that way. It did not. Despite repairs, it exceeded design requirements before failing.

The vertical stab failed right where they put the clamp fix that didn't work. Actually reading the report might help us dispose of this nonsense.

The procedure outlined in the AAMP programme was designed for the DC-9/MD-80 fleet and was only applicable to those types due to the design aspects of the aircraft.Actually it was applicable to anything but only in the most extreme circumstances; excessive roll and no control through lateral channel and was certainly not intended to be used for minor roll disturbance.

. If that SAM had hit 1m closer to a critical part of the aircraft it would have been a smoking hole in the ground.It hit in the engine and blown away all hydraulics. Apart form destroying engine, how could it be more critical for IR guided MANPAD?

And I'm sure that a 737 in Sully's hands would have resulted in exactly the same outcome. It couldn't have hit in alpha prot mode, there is no such thing on 737. Actually reading the report....

CONF iture

21st Mar 2013, 15:43

It couldn't have hit in alpha prot mode, there is no such thing on 737.
Then he could have flared at his liking.

Owain Glyndwr

21st Mar 2013, 18:26

Confiture

Quote:
Originally Posted by Clandestino
It couldn't have hit in alpha prot mode, there is no such thing on 737.

Then he could have flared at his liking.

So are you now suggesting that alpha prot mode was a factor in limiting Capt. Sullenberger's ability to flare?

CONF iture

21st Mar 2013, 19:16

So are you now suggesting that alpha prot mode was a factor in limiting Capt. Sullenberger's ability to flare?
Always have been.

sevenstrokeroll

21st Mar 2013, 20:38

First off...the American Airlines A300: crash could have been avoided in three ways.

1. Stronger Rudder
2. Rudder Limiter
3. Placcard onInstrument Panel: DO NOT USE FULL RUDDER above 200 knots (sic)

It would not have happened on a Douglas with a rudder limiter for example.

--

Sully and his splash. A few things could have helped sully flare more...lack of alpha protection would be one.

If the engines had not had limiters/computer control would they have run long enough for a landing on airport .

If the engines had been mounted on the tail like an MD80, would both have been hit ?

If the engines were pratt and whitney JT8d's, would they have kept running?

and my favorite...if sully/skiles had banked the airplane even 20 degrees would one engine have been above the birds, one below?

some speculation, some educated guess...oh and if sully had turned immediately for runway 13 at LGA...he might have made it...some sim experiments indicate this.

now...clandestino...why no limiter/placcard on the 300? I've seen placcards like that on the sabreliner, and limiters on many jets.

bubbers44

21st Mar 2013, 21:04

SSR is right. Too much automation restricted how Sully could control his Airbus. He couldn't flare exactly the way he wanted to, he couldn't coax the engines to have enough thrust to make an airport and he might have felt he had enough thrust to return and land downwind.

bubbers44

21st Mar 2013, 21:13

Also looking out the window helps. I have avoided thousands of turkey buzzards flying into TGU Honduras flying between flocks, missing indivicual birds and looking for them early, not when they are right in front of you. It isn't very hard to do. I did it for 6 years and only hit one that we tried to dodge two times but he kept going with us. No damage but a 4 lb bird makes a big thump and we stayed at low altitude in case we popped some rivets.

Lonewolf_50

21st Mar 2013, 21:17

seven stroke, didn't most sim attempts at that fail? There's a thread here on that, but I don't recall that discussion other than being interested in how one simulates the surprise of that when people know about Sully's water landing flight.

bubbers44

21st Mar 2013, 21:45

Sully landed in the Hudson with no loss of life. He did everything right. Yes he may have been able to return for a downwind landing but if it failed we would have a lot of dead people so I agree with his decision.

I have a flight sim 2000 in my computer that I have tried because of the turkey buzzards in TGU Honduras to simulate a bird strike with dual engine failure in a 757. I have tried the standing it on a wingtip return to land downwind because that is the only survivable outcome with the terrain and it is 50/50 on how it works out. If you land short you hit a 70 ft cliff and if you land long you go off the end up a hill but it still is your only chance of survival. If they had a big river I would take my chances on that but they don't.

sevenstrokeroll

21st Mar 2013, 22:39

Lonewolf. What I read about the sim attempts...

When an immediate turn was made, 4 out of 4 pilots made LGA.

When a 30 second, WTF, delay was added, none made LGA.

So...you see birds, you feel the bumps and lose power...how long a "WTF" delay do you have?

Now, I haven't flown the airbus. I could have been a captain on the AB320 for sully's airline. I took a 737 bid instead...it paid less too.

But I sure have flown out of LGA an awful lot...and yes me and my friends all looked down the Hudson and thought it would be a good place to land...and I give you my word it was before Sully landed there that we thought of it.

I also looked out on the Interstate 80 freeway and thought it might work too.

But I stand by my comments and echo the comments of Bubbers...you have to be looking out the freaking window and be ultra alert. Alertness can shift for different things at different altitudes. At low altitudes, small planes, big planes, birds and terrain...and all pilots should have that ''pre selected" emergency landing spot.

I also believe in what I said about banking to protect the engines, placing them below and above the formation of birds.

And I know if the DC9 had been hit by birds, it would have made KCLT on time just needing a nice washing if there was time.

bubbers44

22nd Mar 2013, 00:27

If they had made the turn back at engine failure they may have made the runway downwind but if they had people would have probably died. Good for the pilots choosing the Hudson.

Ashling

22nd Mar 2013, 00:30

Sully did a great job on the day and we can only hope that, if called upon, we could perform as well.

However he didn't do everything perfectly and flew @ 15-20kts slow for the config he was in for a good deal of the time and was unaware that he was doing so for bits of it. Thats why he ended up in alpha protection at about 200'

Maybe in a 737 (which will let you stall) he could have finessed the flare a bit or maybe he would have stalled, we will never know. The Airbus prevented us finding out as it stopped the aircraft's alpha increasing @ 3 degrees short of the stall by entering Alpha Prot. In my view thats better than risking a stall, I accept others see it differently

While we may not be able to agree on the merits of Airbus's control laws, and they are complex, hopefully we can agree that flying 15-20 kts below manoeuver speed is not ideal.

bubbers44

22nd Mar 2013, 00:43

30 seconds ia a lot of time. I don't fault them at all for landing in the Hudson.

CONF iture

22nd Mar 2013, 04:36

The Airbus prevented us finding out as it stopped the aircraft's alpha increasing @ 3 degrees short of the stall by entering Alpha Prot.
Not 3 deg short of the stall, 3 deg short of alpha max which is itself probably another 3 deg short of the stall. Full back stick the Airbus is supposed to deliver alpha max not to stop 3 deg short. The Airbus documentation is simply misleading.

While we may not be able to agree on the merits of Airbus's control laws, and they are complex, hopefully we can agree that flying 15-20 kts below manoeuver speed is not ideal.
Agree.
Now if you think Sully maybe would have stalled a 737, that's a question you should direct to him and wait for the reply ...

In my view thats better than risking a stall, I accept others see it differently.
Fair enough.
What is not acceptable is uninformed comment, btw made by a guy who obviously see himself as la crème de la crème :
Both Habsheim and Hudson have one more common trait besides both involving A320: both aeroplanes hit the deck in alpha prot with significant aft stick displacement. If flight controls were classical or brand B FBW with overridable limits, outcome would be much worse.
For the record, that last quote is not yours.

Clandestino

22nd Mar 2013, 09:17

Well, I do stand corrected: seemingly it is not enough just to read the report/manual/aeronautical textbook. One also needs to understand what is written. We have been recently given with good examples why it's so and I'd like to express my gratitude to certain posters for amusement they provided.

AA587 fin failed in overload. It was overloaded due to extreme sideslip. Sideslip was brought through aircraft-pilot coupling resulting in divergent yaw oscillation. Folks understanding the term "divergent oscillation" know that no amount of beefing up the structure or reducing rudder authority can help combat it yet proper use of the rudder will never, ever cause it. Fortunately, all of the aeroplane designers and those tasked with certifying aeroplanes do understand that. All pilots should too.

Microsoft flight simulator is very useful tool for teaching IFR procedures but that's about it. Aerodynamics isn't and wasn't meant to be simulated realistically. Therefore, arguments such as "I performed that in MSFS" are not considered to be quite relevant on the Professional Pilots Rumour Network

As for Airbus being misleading:

the Flight Crew Operating Manual is not intended to provide basic jet aircraft piloting techniques or information that are considered as basic airmanship for trained flight crews familiar with that type of aircraft and with its general handling characteristics.

(...)

the Flight Crew Operating Manual is not intended to be used for teaching basic piloting skills...nicely sums it up.

Claiming that airbus FBW should provide flight just below Alpha crit, with no margin since this could improve flare (Hudson) or improve climb (that infamous low & slow flyby with trees getting in the way) is cheerfully disregarding that it's not just Cl that rises just below the stall but Cd also. Such an argument may solicit reaction or give its originator not altogether savoury reputation on PPRuNe but its informational value is nil.

Wether captain Sullenberger woud have used same control inputs if it were 737 is matter of conjecture. Whether 737 approaching flare 15 kt too slow with full back yoke would have stalled is not.

What is not acceptable is uninformed comment

PPRuNe would have been much poorer if it indeed were so.

Ashling

22nd Mar 2013, 09:52

[QUOTE=CONF iture;7754612]Not 3 deg short of the stall, 3 deg short of alpha max which is itself probably another 3 deg short of the stall. Full back stick the Airbus is supposed to deliver alpha max not to stop 3 deg short. The Airbus documentation is simply misleading.

You are right that Airbus's docs fail to mention that pilot inputs may be attenuated in Alpha Prot, as Sully's were, but to an extent it's common sense. Close to the limit control inputs are dampened. On conventional aircraft this is what you would do for yourself, E.G. a max rate turn, pull to the edge of the buffet then squeeze into it to avoid pulling into the heavy buffet. You attenuate your input close to the limit. The advantage of FBW is that you can make that input as aggressive as you want.

As the NTSB noted the aircraft max performed but as you, and they, note that is different to Alpha Max which is @ 3 degrees short of Alpha Stall so he was 4 to 5 degree's short of the stall AOA when he went in. We disagree about the significance of that, I feel the aircraft max performed and protected him, you feel it prevented him cushioning the impact better. The NTSB seem ambivalent about it other than saying the docs could be clearer on it and Sully's speed control could have been better. I don't want to revisit our lengthy debate, I respect your point of view even though I have a different take on it.

I believe the 3 degree gap between Alpha Max and Alpha stall is down to regulatory requirements for FBW and relates to ice formation on slats and flaps which cannot be simulated during flight tests.

No one, not even Sully, can say what would have occurred in a Boeing its conjecture. That applies to both of us Confiture.

The Airbus over rode the low speed warnings with GPWS warnings and given Sully's workload it is understandable that he didn't pick up on the speed, as the NTSB highlight. At the end of the day you fly the aircraft you are in.

My point is that if the speed control is correct the debate about control laws limiting inputs is irrelevant as is whether he would have stalled in a Boeing. We have the great luxury of thinking about all this at our leisure and in my view one of the things we should take away from it is the importance of speed control and scanning the speed tape as other warnings may mask the low speed ones. Sully did not have that luxury but admidst it all saved everyone's lives, I only have respect for what he achieved and hold him in the highest regard.

Owain Glyndwr

22nd Mar 2013, 12:10

Confiture,

Forgive my ignorance, but there is something I do not understand here. On March 8th you said:
11 degrees attitude is optimum for all cases, thrust or none.

Now if the object is to minimise the rate of descent (flight path gradient) at impact and if the 'best' that pilots could do was a gradient of -1.5 degrees (NTSB report), then the target 'optimum' AoA would be about 12.5 degrees (or lower) wouldn't it? If that is so, why are you complaining that the control laws "prevented" achievement of alpha prot threshold or alpha max?

For memory, the alpha prot. threshold was 15.5 deg below 50 ft and alpha max was 17.5 deg - both of these from the NTSB report.

I can see that the attenuation of pilot's controls that accompanies the alpha prot mode could have limited his ability to get more than 9 deg pitch in the time he had available for flare starting from 50 ft, but the impact on the Hudson was between 13 and 14 deg AoA according to the NTSB, so I do not understand why you think inability to get to the alpha prot AoA threshold so important.

What am I missing?

Capn Bloggs

22nd Mar 2013, 15:23

No one, not even Sully, can say what would have occurred in a Boeing its conjecture.
:confused:. He'd pull just into the buffet, as you described earlier in your post, and hold it there. Or are you suggesting he'd possibly pull straight thru and stall/spin in?

Lonewolf_50

22nd Mar 2013, 16:24

seven stroke, thanks for that, no further questions.

bubbers44

22nd Mar 2013, 21:32

LW50, it makes sense, either turn back and land immediately at lower altitudes or forget about that option. Also make sure you can do it. I have seen the other result with a vertical plunge into the ground with my own eyes at Burbank with a Bonanza losing an engine and trying to rudder back for a landing going straight in with 4 people. I taught cross control stalls as a flight instructor to prevent this type of accident.

Ashling

22nd Mar 2013, 23:50

Capn Bloggs, the point is we don't know what would have happened in a Boeing. You may feel he could have pulled it into the buffet and held it, thing is you don't know just as no one can say he would have stalled had he been in a Boeing.

What you can say is that if he got that slow in a Boeing and then pulled hard back and held it he would have stalled but somehow I doubt he would have done that had it been a Boeing. Mind you I also doubt whether he, or anyone short of those who stall the aircraft regularly, could pull into buffet and hold it in those circumstances.

Speed control, monitoring and knowing that low speed warnings can be masked by other things is one of the key lessons from the Hudson imho. While its understandable that Sully's speed control was not ideal, task saturation, I'd assume no one here is saying that flying 15-20kts slow prior to the flare is the best way to ditch an aircraft. Its that speed control that led to the difficulty flaring, not the design of the aircraft.

bubbers44

23rd Mar 2013, 00:50

No one looking at the smooth splashdown could say he didn't do it perfectly. Rate of descent was almost zero and attitude and bank were perfect. Sully did a great job. Hopefully we could have done likewise. I think most of us could but we fortunately don't get to be tested.

bubbers44

23rd Mar 2013, 00:56

Type of aircraft isn't important, pilot skills are so I give all the credit to Sully because he could have done it in any airplane. He started out in smaller planes and just happened to be in an Airbus.

Ashling

23rd Mar 2013, 10:00

According to the NTSB the rate of descent at splashdown was @ 12.5 ft a second or 750 ft per minute.

bubbers44

23rd Mar 2013, 13:31

Surveillance Cameras Capture Flight 1549 Crash Landing into the Hudson River - Video (http://www.metacafe.com/watch/2310586/surveillance_cameras_capture_flight_1549_crash_landing_into_ the_hudson_river/)

This shows the splashdown from surveilance video. It looks pretty normal to me.

Ashling

23rd Mar 2013, 14:42

Bubbers, that statement to me illustrates a real problem with the Hudson ditching.

Sully and his crew did a great job and were rightly praised but just because the outcome was successful does not mean we suspend our critical faculties. We still need to look at the incident and determine the lessons to be learnt. There are things to learn from all the great things they did but there are also lessons to be learnt from what could have gone better. Unfortunately some only look at the outcome and seem to pretend that all was perfect.

The importance of speed control and monitoring, to me, is the key lesson from the what could have gone better category.

Fact is he got slow, upto 19kts slow, that is well documented by the NTSB and beyond dispute. Its why he entered Alpha Prot and why the flare was problematic. It's also fact they splashed down at 12.5 FPS 750 FPM and I rather suspect the NTSB had access to the camera footage too but seem to have drawn a different conclusion to the one Bubbers does. But, hey, what do the NTSB know?

misd-agin

23rd Mar 2013, 19:04

And I know if the DC9 had been hit by birds, it would have made KCLT on time just needing a nice washing if there was time.

sevenstroke - read the accident report. No jet engine would run with useable power with the damage the engines had.

misd-agin

23rd Mar 2013, 19:07

Ashling - exactly. Critical analysis would review all the things done correctly and less incorrectly.

Reviewing the FDR and CVR is interesting.

Due to low airspeed(AOA limit) there was no flare. Same as BA 038.

sevenstrokeroll

23rd Mar 2013, 20:33

misd again...

I didn't say the engines on the DC9 would get damaged.

First off, if you are going to hit the engines on a DC9 (and they have been), you have to get by the fuselage, they aren't just sticking out in front of the wing.

Now, you mention damage...and that presumes the bird can do the damage...but the inlet on the jt8d is much smaller than the inlet/fan on the CFM 56, right?

maybe the birds would hit the bullet or the lip and not get by.

and of course the engines are not FADEC , just good old fashioned fuel controllers.

so...its my view...and of course unless you come up with the big bucks, the birds and a DC9, we won't really know.

but do look at a flock of birds...its almost like a anice delta wing...if they hit the 9 on the nose, would they get to the engines? of course they would on the airbus or 737...but

anyway...yes sully did fine...any landing you can swim away from is just fine.

could it have been better? I think so. But any landing you can swim away from is just fine.

And I hope all the pilots out there think about how they could do better, what they might do better etc...and not just accept that sully did it perfectly.

CONF iture

24th Mar 2013, 19:51

What am I missing?
You would probably need to question Airbus as the airplane was in alpha-protection mode from 150 feet to touchdown.
The airplane reached 9 deg of AoA when the alpha-protection threshold value was still at 8 deg.
Obviously the alpha-protection threshold value is dependent of the altitude and configuration. AFAIK those values are nowhere in the Airbus documentation reserved to the pilot. They only appear in the different incident/accident reports.

Now, how do you call an "attenuation of pilot's controls that accompanies the alpha prot mode which could limit the ability to get more than 9 deg pitch in the time available for flare starting from 50 ft" if not a restriction ?

Let Sully pull another 2 deg of pitch to obtain the recommended attitude for ditching and benefit from it by decreasing his vertical speed at touchdown.
Adequate margin was in the aerodynamics as alpha max was still 4 deg away.
No immediate risk for stalling.

Claiming that airbus FBW should provide flight just below Alpha crit, with no margin since this could improve flare (Hudson) or improve climb (that infamous low & slow flyby with trees getting in the way) is cheerfully disregarding that it's not just Cl that rises just below the stall but Cd also.
Margin is already included, that's why alpha max is not set at alpha stall.
Also the benefit from the CI rise over the Cd rise is exactly what is needed for the short term and that's what Airbus figured out by implementing alpha max ... as long they allow to get it.

misd-agin

24th Mar 2013, 20:45

sevenstrokeroll - the birds went right into the compressor section. Bullseye, and bullseye on any engine.

FADEC vs. cable controls doesn't matter if the core inlet is blocked and/or damaged so severely that it's continously compressor stalling.

What's the size difference between a JT8D vs. a CFM56? Compressor inlet difference is probably minimal.

pattern_is_full

24th Mar 2013, 21:05

JT8D (on DC-9) - fan diameter 39.9 inches; area 1250 in^2

JT8D-200 series (MD-80 et seq.) was larger. 49.9 inches diameter

CFM56-5B - fan diameter 68 inches; area 3631 in^2

I also expect 7sr's point was that the engines are protected by wing and fuselage airflow (and the wing itself to some extent, in a climb attitude):

http://www.fiddlersgreen.net/aircraft/Douglas-DC9/IMAGES/Douglas-DC-9-NASA.jpg

http://cdn-www.airliners.net/aviation-photos/photos/4/9/2/1171294.jpg

(although - ahem - that second picture is probably not how one would wish to achieve a climb attitude.)

misd-agin

25th Mar 2013, 01:24

The engines couldn't develop power because of the damage to the compressor blades and VSV's. That's downstream of the core inlet and fan diameter does not apply.

Owain Glyndwr

25th Mar 2013, 08:18

Confiture:
The airplane reached 9 deg of AoA when the alpha-protection threshold value was still at 8 deg.
Obviously the alpha-protection threshold value is dependent of the altitude and configuration. AFAIK those values are nowhere in the Airbus documentation reserved to the pilot. They only appear in the different incident/accident reports.
Well one needs to exceed the alpha-protection threshold to trigger alpha-protect mode doesn't one?
The principle of alpha-protection is well documented though, and it is difficult (for a non-pilot) to see what practical use could be made of a knowledge of the actual numbers since as we all know, AoA is not displayed to the pilot.

Now, how do you call an "attenuation of pilot's controls that accompanies the alpha prot mode which could limit the ability to get more than 9 deg pitch in the time available for flare starting from 50 ft" if not a restriction ?The very fact that I phrased it in the way I did shows that I accept there was a restriction. [comment on pitch rate limitation removed 26/03]

Let Sully pull another 2 deg of pitch to obtain the recommended attitude for ditching and benefit from it by decreasing his vertical speed at touchdown.Agreed that if he could have pulled to another 2 deg he could have reduced his vertical speed, but the fuselage crushing loads have two components, one of which is speed/AoA dependent so it is not obvious he would have been significantly better off (if in fact you can be better off than a ditching where everyone gets out OK).

But I note that other pilots, presumably using different flare techniques, managed to achieve the desired low descent rates, which leads me to believe that the control attenuation was a limit on Sully's flare but may not be generally applicable.

Margin is already included, that's why alpha max is not set at alpha stall.Can you please point me to a reference for that statement? It is not how I understood the system.

Clandestino

25th Mar 2013, 08:38

First off, if you are going to hit the engines on a DC9 (and they have been), you have to get by the fuselage, they aren't just sticking out in front of the wing. Any engine that provides thrust by sucking in air and imparting it momentum as it is ejected needs clear and ample supply of aforementioned air, therefore any jet engine equipped with intake is prone to birdstrikes. If fuselage or wing get into position to shield the engine from birdstrike, they also shield it from uninterrupted airflow and that's something that usually causes big and expensive engine buuurp at high power settings. Protections that PWC150 or Klimov RD-33 enjoy are just impossible to apply on civil turbofans.

The airplane reached 9 deg of AoA when the alpha-protection threshold value was still at 8 deg.

According to FDR data, the airplane touched down on the Hudson River at an airspeed of 125 KCAS with a pitch angle of 9.5° and a right roll angle of 0.4°. Calculations indicated that the airplane ditched with a descent rate of 12.5 fps, a flightpath angle of -3.4°, an AOA between 13° and 14°, and a side slip angle of 2.2°.

Now, how do you call an "attenuation of pilot's controls that accompanies the alpha prot mode which could limit the ability to get more than 9 deg pitch in the time available for flare starting from 50 ft" if not a restriction ?Aerodynamics.

Adequate margin was in the aerodynamics as alpha max was still 4 deg away.Maybe in Robert Zemeckis' movies or Michael Crichton's novels. Real life NTSB mentioned that the FBW helped wrung out as much performance as it was possible. Too bad that it doesn't fit "Airbus baaaaad" theory.

Also the benefit from the CI rise over the Cd rise is exactly what is needed for the short termBelow Cl/Cd max Cd rises faster than Cl but then it is not enough to understand just aerodynamics to know that. One has to be versed in basic arithmetics also.

Ashling

25th Mar 2013, 12:23

Owain

If you look in the FCTM under Operational Philosophy, Protections, High Angle of Attack Protections, there is a graph that makes it pretty clear that V alpha max is short of V Stall 1g

Alpha Prot also increases by 1degree in the last 50ft provided the Config remains the same. That's not in the books as far as I know.

There is also a graph below that one that makes the point that FBW aircraft significantly outperform non FBW aircraft when it comes to pulling up suddenly from low speed in the approach Config at Vapp converting to max AoA.

Type in Airbus 320 phugoid damping into google and a couple of interesting articles come up.

sevenstrokeroll

25th Mar 2013, 13:51

clandestino...and tell us of the PW engine on the king air?

and tell us if a bird hit the fuselage and was ripped apart prior to entering the intake?

sorry clandestino...you must account for more than basic suck, squeeze bang blow

Owain Glyndwr

25th Mar 2013, 14:13

Ashling,

Thank you for that google tip; the Airbus submission to the NTSB was particularly interesting, as I hadn't realised that when in alpha-protect the aircraft develops a phugoid. In normal law there isn't a phugoid. So then we have:

There are feedbacks within the AoA protection law aiming at damping the phugoid mode (low frequency mode). Without these feedbacks, an aircraft upset from its stabilized flight point up to constant high AoA would enter a phugoid (which is, by definition, a constant AoA oscillation) without possibility to stabilize the trajectory. As a consequence, commanded AoA is modulated: for instance, if aircraft speed is decreasing and/or pitch attitude is increasing, pilot's commanded AoA is lowered in order to avoid such a situation to degrade.
Trying to run simulation without such damping features on the very last seconds of the flight, without considering what could have been the effect such features brought upstream during the flight on the overall Aircraft trajectory and management by the crew would be pure speculation, as not supported by technical facts.
On the last 10 sec in the air of Flight 1549 , DFDR data show that pitch attitude is increasing and CAS decreasing. Then, the phugoid damping terms are non null and are acting in the sense to decrease the finally commanded AoA vs. the stick command, in order to prevent the Aircraft from increasing the phugoid features.
......
..... with a loss of engine thrust, as in Flight 1549, the aircraft energy management significantly increases the pilot workload. Under these circumstances, aircraft is still able to reach the optimum water impact configuration, but this is a demanding task which requires time and significant pilot focus. Typically, the flare initiation height will be critical to the achievement of the optimum water entry conditions.
Now that means that the features that limited Sully's flare are necessary for stability and that removing them might have adverse consequences on the approach to flare. [edited 26/03]

Also, that last sentence is, IMHO, the key - height of flare initiation is the important parameter.

BTW, the picture I have seen illustrating the various 'alphas' is a schematic with the differences dictated by presentational requirements as much as actual values. I would be surprised if there was much between alphamax and alpha stall - the commercial pressures are too high to allow much leeway when competitors are basing their products on alpha-stall

bubbers44

25th Mar 2013, 22:03

I think most of us would have held best glide speed for flap configuration and flared to stop 750 fpm descent below 50 ft. I still see a normal touchdown rate well below 750 fpm in the video but I know what 750 fpm profile is and it would have a mighty big splashdown. His looked normal. Look at the video. The NTSB was probably looking at his final descent before flare. Yes, he would have done better with a 737 but he was flying an Airbus and was restricted to Airbus rules. That is why I never flew the Airbus. If it aint a Boeing, I ain't going.

bubbers44

25th Mar 2013, 23:09

I know I am prejudiced against Airbus but still am happy I never had to fly one. One happy Boeing pilot.

Ashling

25th Mar 2013, 23:55

Bubbers, do the google search I suggested above, look at analysis by the chairman of the board that comes listed as 1 or 2. All the FDR graphs are at the end. Either every sensor was out or they hit at 750fpm. Sorry just the way it is, looks can be deceptive.

Not so sure about the Seattle Tractor mind you, rudder hard overs, fuel filters clogging snuffing out both engines, cargo doors flying off taking pax along for the ride, batteries burning, rad alts that force the engines to idle, spoilers that don't stow when you firewall the engines which ain't great for GPWS pull ups as you tend to hit the hill etc etc

I've flown both, and enjoyed flying both and am gratefull I've had the chance to do so. They're aircraft, they both have good and bad points, both can kill you if you get sloppy and haven't done your homework or are just plain unlucky.

Maybe he would have done better in a 737, maybe he would have done worse. We will never know. We can, however, surmise that had his speed control been the same its pretty likely he would have triggered a stall warning. As I recall there's no AOA gauge in the 737 so no way to know the margin therefore you have to honour the warning by pushing or at the very least holding the attitude. That might be tricky at 150' and 1200 - 1500 fpm rod. At least in the Bus (in normal law because he started the APU) he could pull with confidence that the aircraft would not stall. Just a thought.

misd-agin

26th Mar 2013, 01:44

AA and DL 737 NG's have AOA gauges on the PFD(top right corner) and on the HUD(top right corner).

The overwhelming majority of guys never look at it.

sevenstrokeroll

26th Mar 2013, 02:02

boys and girls...its been an interesting thread.

flares, laws, engine inlets, birds, good job, could have done better etc.

I dare say this conversation should have been part of the investigation, but as jimmy stewart said in the film, "The man who shot liberty valence", PRINT THE LEGEND.

IF you are good and lucky, I'll take a DC9 or 737 (prefer DC9). If you are average, maybe an airbus might be better...
but all in all, better to be lucky than good!

bubbers44

26th Mar 2013, 02:38

I agree, a good pilot would have been better off in something other than an Airbus. The Airbus keeps pilots from doing stupid things like stalling.

Ashling

26th Mar 2013, 09:01

I've known a-lot of good pilots who have done stupid things.

misd-agin

26th Mar 2013, 13:47

An airplane that prevents people from doing stupid things is bad?

sevenstrokeroll

26th Mar 2013, 14:01

a plane that prevents stupid things...great

but...that also prevents heroic things...that's bad.

I AM REMINDED of the general aviation plane called the MOONEY...some of you will know where I am going with this.

The Mooney has a full time ''wing leveler''. And a little tiny button on the yoke that turns it off so you can make a turn.

IN essence, you never have to demonstrate straight and level flying, as the wing leveler is doing it for you .

So, how about the airbus having a little button on the yoke that you press to over ride all protective LAWS?

Need to bank 80 degrees? Press the button MAX!

Need to stall? PRESS THE BUTTON MAX!

And all the other times the plane is watching and protecting you from being stupid.

CONF iture

26th Mar 2013, 14:28

Well one needs to exceed the alpha-protection threshold to trigger alpha-protect mode doesn't one?
The airplane was under alpha protection mode for the last 150 feet, that's in the report. I am usually the one to question the Official Reports ...

The principle of alpha-protection is well documented though, and it is difficult (for a non-pilot) to see what practical use could be made of a knowledge of the actual numbers since as we all know, AoA is not displayed to the pilot.
That information is not vital but it is nice to know how your aircraft is working.
Time after time incident/accident reports provide bits of values and this make much more interesting readings than the FCOM to comprehend the System you're working on.

Agreed that if he could have pulled to another 2 deg he could have reduced his vertical speed, but the fuselage crushing loads have two components, one of which is speed/AoA dependent so it is not obvious he would have been significantly better off.
If you obtain the recommended attitude for ditching and reduce your vertical speed at impact in the meantime it is a simply a win win situation for the fuselage and the passengers.

Can you please point me to a reference for that statement? It is not how I understood the system.
The system has been designed to protect the airplane from stalling but also to provide the maximum performance when most needed : escape from a ground contact. The Airbus pilot is requested to apply fullback stick without thinking in given escape maneuver situations. Alpha max is taking care to deliver that maximum lift in the minimum time without taking the risk for stalling. They could have set alpha max just short of alpha stall where the immediate needed performance is even better but that would have been too border line. And the increase of drag is not an issue as the immediate increase of lift is the ultimate goal. Clandestino has some difficulty to grab that point.

Capn Bloggs

26th Mar 2013, 14:36

The Great Race!

sevenstrokeroll

26th Mar 2013, 19:10

capn bloggs

is correct. May the Leslie Special always yield to you.

DozyWannabe

26th Mar 2013, 21:00

Need to bank 80 degrees? Press the button MAX!

Need to stall? PRESS THE BUTTON MAX!

Question : In what hypothetical situation would you be required to do either of those things in an airliner?

The system has been designed to protect the airplane from stalling but also to provide the maximum performance when most needed : escape from a ground contact. The Airbus pilot is requested to apply fullback stick without thinking in given escape maneuver situations.

The pilots aren't "requested" to do anything - they can handle it as they see fit. The *system* is designed such that in Normal Law (i.e. in excess of 99% of the time), it is possible to command full stick deflection without risking the aircraft's stability. You can even pull at 67 degrees of bank to tighten the turn if you wish.

bubbers44

26th Mar 2013, 23:45

The Airbus performed as designed in the Hudon crash. The B737 would have done better because they could have got another degree of pitch to make the splashdown perfect. The Sully splashdown was just fine however.

DozyWannabe

27th Mar 2013, 00:03

You do make me smile, bubs. Judging by all the data I've been given on the subject, the difference would have been utterly negligible - and that's without taking into account what having the empennage in contact with the water for longer (as a consequence of increased pitch attitude) might have done to the structural integrity.

I've long since been resigned to the idea that CONF iture is going to tilt at his windmills no matter what he's told or by whom.

CONF iture

27th Mar 2013, 00:06

The pilots aren't "requested" to do anything
Of course they are.
What do you think means PULL UP TOGA ?

DozyWannabe

27th Mar 2013, 00:13

In what context?

bubbers44

27th Mar 2013, 00:18

DZW, thanks for the support.

CONF iture

27th Mar 2013, 00:51

In what context?
“PULL UP” - “TERRAIN TERRAIN PULL UP”

and that's without taking into account what having the empennage in contact with the water for longer (as a consequence of increased pitch attitude) might have done to the structural integrity.
Advise Airbus they have it wrong with the recommended attitude.

DozyWannabe

27th Mar 2013, 01:35

“PULL UP” - “TERRAIN TERRAIN PULL UP”

That's a GPWS warning - not specific to Airbus. And while - everything else being OK - the PF of a FBW Airbus *can* slam the stick against the back stop with little negative impact, that doesn't mean that they necessarily should.

Advise Airbus they have it wrong with the recommended attitude.

That's not what I'm saying - I agree with Owain Glyndwyr that the recommended pitch of 11 degrees is dependent on other parameters being within a certain range and cannot be taken in isolation. There are far too many other variables involved to draw a conclusion on whether a difference the flare would have made any difference, either positive or negative.

Clandestino

27th Mar 2013, 09:50

and tell us of the PW engine on the king air?Yeah... how many PT6 we would need to propel 160 seater at 0.78 Mach?

When it comes to carrying 100+ people over mid and long ranges, there is no viable alternative to short-inleted turbofan and there is no way to protect them from birdstrikes.

you must account for more than basic suck, squeeze bang blow But not in a such manner that this "more" gets us in completely wrong direction, such as giving us ludicrous idea that fuselage somehow shields the engines from birdstikes.

I know I am prejudiced against Airbus but still am happy I never had to fly one. One happy Boeing pilotGood for you. As long as you have no valid argument to support your prejudices, irrelevant for the rest of the world.

boys and girls...its been an interesting thread.Indeed. Usual folks who harp about Airbus FBW being bad and today's pilot not knowing how to fly are so out of arguments they have to use the thread about incident that no one so far has proven happened at all to air their unsubstantiated ideas such as:

IF you are good and lucky, I'll take a DC9 or 737 (prefer DC9). If you are average, maybe an airbus might be better...

I am usually the one to question the Official Reports ...Everyone is free to question the official reports. Such an action can yield useful results only if one understands them. Otherwise, entertainment ensues.

If you obtain the recommended attitude for ditching and reduce your vertical speed at impact in the meantime it is a simply a win win situation for the fuselage and the passengers.Where would you get your additional attitude as aeroplane was already at 13° AoA and engines were not producing power? See previous entry.

Clandestino has some difficulty to grab that point. Thank you for once again mounting personal attack when out of anything resembling coherent and valid argument but I'll have to disappoint you: I perfectly understand that point, made on completely wrong understanding of a) aerodynamics b) measuring and tolerances of air data. I'd suggest renting out a C-172 with instructor and asking him to demonstrate slow flight, culminating in a couple of stalls would help in understand just how usable are last couple degrees of AoA before stall. It's not much.

The B737 would have done better because they could have got another degree of pitch to make the splashdown perfectAt 15-20 kt below optimal speed with wrecked engines, no way in hell.

Advise Airbus they have it wrong with the recommended attitude. Airbus doesn't care if some anonymous poster at some anonymous forum thinks they are wrong, especially if such a belief comes from his inability to understand the basic aerodynamics. You can't have optimal attitude with optimal RoD if you are below optimal speed.

And while - everything else being OK - the PF of a FBW Airbus *can* slam the stick against the back stop with little negative impact, that doesn't mean that they necessarily should.We are derailing this thread, but as long as aeroplane is in normal law and pilot is not 100% sure that GPWS warning should be disregarded (false alarm, forced landing) - he should.

CONF iture

27th Mar 2013, 13:07

Where would you get your additional attitude as aeroplane was already at 13° AoA and engines were not producing power?
Ample margin In the AoA itself as alpha max is over 17 deg. Alpha max is not alpha stall yet - remember that ?
2 additional deg of attitude to improve the touchdown.
Engine thrust is irrelevant.

I'd suggest renting out a C-172 with instructor and asking him to demonstrate slow flight, culminating in a couple of stalls would help in understand just how usable are last couple degrees of AoA before stall. It's not much.
More than enough to improve the touchdown - Will you be the instructor ?

Airbus doesn't care if some anonymous poster at some anonymous forum thinks they are wrong, especially if such a belief comes from his inability to understand the basic aerodynamics.
Is it directed to Dozy, he's the one to think that the recommended attitude for ditching by Airbus might do something to the structural integrity.

You can't have optimal attitude with optimal RoD if you are below optimal speed.
Yes you can as long as you keep it for the flare.
You wouldn't flare at 1000 feet would you ?

CONF iture

27th Mar 2013, 13:14

That's a GPWS warning - not specific to Airbus. And while - everything else being OK - the PF of a FBW Airbus *can* slam the stick against the back stop with little negative impact, that doesn't mean that they necessarily should.
Deliberate deviation from a Procedure. Some have paid the big price for doing so.
What's your experience again ?

There are far too many other variables involved to draw a conclusion on whether a difference the flare would have made any difference, either positive or negative.
Anything else to say ... to say nothing ?

sevenstrokeroll

27th Mar 2013, 13:42

now I am sure there are a number of non airline pilots talking out their APU exhaust.

I've seen too much and too much misunderstanding. It is almost too much...

But I do wonder about the S like ducting in a 727 and how a bird might be ripped apart prior to hitting the fan.

I do wonder about people who are looking for a time that stalling a plane or banking very steeply might not be used

And when someone has the lack of understanding to project incorrect speeds in one type vs another...I quake.

so, fly your airbus just as the computer says. Hal will take good care of you. Ask the Air France boys! And waiting for the computer to reset after an upset...oh yeah!

It boils down to this...a pilot must be able to fly the wings off a plane in order to save it...and if the computer says no, you might as well not have a pilot on board.

And, for those brilliant ones here, Seeing the vulnerability of a large fan inlet vs a smaller one and just LUCK in the exact position of a bird vs the inlet at any time, considering the spacing of birds in formation...well, you believe what you want. Prove me wrong...take a plane up into a formation of birds...video it and see exactly how the birds might react to a fuselage vs just an inlet...do it with a number of aircraft types and report back.

All those who have flown transports out of LGA, raise their hands.

! = hand raise

others , need not apply.

Owain Glyndwr

27th Mar 2013, 16:30

Is it directed to Dozy, he's the one to think that the recommended attitude for ditching by Airbus might do something to the structural integrity.

He's not the only one:-

It also shows that in case of water impact with an aircraft pitch below ≈ 8°, or above ≈15° major airframe structural breakage is expected.Source: Airbus submission to NTSB Flight 1549 investigation

11 deg is nearly in the middle of that range, but departure away from that optimum on either side is bound to have a bad effect, although it is very possible that for reasonably small deviations the effect is not large (nonlinear characteristics).

DozyWannabe

27th Mar 2013, 16:56

Point of order - I'm not saying anything about the recommended pitch attitude causing structural damage, I'm echoing Owain's earlier assertion that the recommended pitch attitude applies only when other parameters are met (which in that case they were not).

The damage to the aft fuselage skin could just has easily have been caused by impact with solid floating debris on the river - in fact given that the pitch attitude was within the recommended limits that Owain posted above, it gives some credence to the idea. Of course there's no way of definitively proving it one way or the other, so IMO it's pointless arguing the toss at this point.

Quite what this has to do with the OP is anyone's guess.

bubbers44

27th Mar 2013, 23:10

Saving some airspeed to make the final touchdown as flat as possible and at the right attitude is important In all types of aircraft if you have no problem with space available to land which they didn't. Some people here say they were 15 knots slow on descent. Looking at the video of the touchdown it didn't look like they had a high descent rate starting their flare. With no power and 15 K slow I know how my landing would be.

Ashling

28th Mar 2013, 00:02

It wouldn't be as good as it would have been had you flown the correct speed and had excess energy and nose authority to flare with.

See your still struggling to accept the FDR traces, NTSB and Airbus ref the descent rate at touchdown.

bubbers44

28th Mar 2013, 00:41

Obviously you cannot maintain700 fpm with no power without a lot of additional airspeed to flare. They seem to have splashed down normally in the video. If anyone can show data below 50 ft please post it. Above 50 ft with no power doesn't mean much with no power.

Clandestino

28th Mar 2013, 08:42

Wonder what you are going to make out of it but here it goes: N106US DFDR trace. (http://dms.ntsb.gov/pubdms/search/document.cfm?fileid=418135&ntsbnum=DCA09MA026)

Ample margin In the AoA itself as alpha max is over 17 deg. Alpha max is not alpha stall yet - remember that ?Ample margin is largely imaginary. Do you have any idea what are your alpha and speed margins at Vref?

More than enough to improve the touchdown - Will you be the instructor ?As long as I am commander, anyone truly believing that couple of degrees more of alpha when it is already over ten can improve touchdown has no business occupying any seat from which flight controls can be reached.

Is it directed to DozyIt might be refreshing change if we started concentrating on what is written, not who has written it.

he's the one to think that the recommended attitude for ditching by Airbus might do something to the structural integrity.He is right.

You can't have optimal attitude with optimal RoD if you are below optimal speed.
Yes you can as long as you keep it for the flare.
You wouldn't flare at 1000 feet would you ?
Keep what? NTSB report clearly shows speed was too low. Not BEA this time, NTSB! There i was we are thinking when someone says "Hudson ditching" it refers to well known, well researched and well documented occurrence, not some imaginary one.

now I am sure there are a number of non airline pilots talking out their APU exhaust.It would be useful if you provided examples and explanations instead of wink-wink-nudge-nudge-you-know-what-I-mean.

But I do wonder about the S like ducting in a 727 and how a bird might be ripped apart prior to hitting the fan.Not at all. Smashed maybe but minced - nope. S ducts of 727 or Tristar are quite different beasts compared to S ducts found on PWC turboprop installations which have bypass door that provided escape route for many a bird carcass.

I do wonder about people who are looking for a time that stalling a plane or banking very steeply might not be usedQuestion was simple, being evasive on it is not conductive to meaningful discussion.

fly your airbus just as the computer says. That would be in breach of operating manuals and, depending on outcome, might even constitute misdemeanor.

Hal will take good care of you. Wont, but that's what anyone reading and understanding FCOM knows.

.a pilot must be able to fly the wings off a plane in order to save itSaving the aeroplane through inducing inflight airframe failure. Needs no further comment.

Seeing the vulnerability of a large fan inlet vs a smaller one and just LUCK in the exact position of a bird vs the inlet at any time, considering the spacing of birds in formation...well, you believe what you want.Aeronautical powers that be believe that cutting the bird with fan and throwing it out through fan bypass duct is not something that can induce immediate catastrophic failure but when it comes to core, there is not much to choose between high and low bypass engines. Blimey, life proves them right.

All those who have flown transports out of LGA, raise their hands.What relevance does it have? That someone believing everyone around here is pilot can now start ranting that pilots flying out of LGA are aeronautical ignoramuses?

Anyway, does anyone have a proof that AA742 really had control problems?

Ashling

28th Mar 2013, 08:53

http://www.exosphere3d.com/pubwww/pdf/flight_1549/ntsb_docket/431658.pdf

Just for you Bubbers, lots of FDR traces for you to peruse. I did refer to it earlier.

Also nice discussion about phugoid damping and the approach to the stall which explains why Alpha Prot works the way it does.

sevenstrokeroll

28th Mar 2013, 20:07

boy...now I'm sure ..

clanestino...fly the wings off a plane...it is an expression...and if you fly the wings off the plane as your wheels touch the ground, you have lost your wings, but saved your passengers...get a life.

high bypass vs lower bypass...think about it...if you have a target that is 200 sq feet in size, and one that is 100 sq feet in siZe and something is trying to hit it, isn't it easier to get a strike on the larger target? Throw in the mix of the bullet (do you know what that is?) and JUST MAYBE THE BIRD WILL HAVE LESS A CHANCE TO HIT AND DAMAGE YOUR ENGINE THAN OTHERWISE.

wink wink, nudge nudge...oh, someone who likes mediocrity in their comedy as well as in their aerial machines.

clandestino...have you measured or even observed the spacing on canadian geese in flight? I haven't measured it, but it appears that the spacing is more condusive to running into the inlet of a CFM 56 than a JT8D.

Now, before you write me again, take that little measuring tape of yours (i'm sure its little) and measure the spacing on the birds.

I am NOT saying if a bird hits the fan on either engine there might not be a problem...but I do say that a bird hitting a smaller target might not be as likely as hitting a larger target.

I do wonder how much sturdier the shorter blades on a JT8D are compared to the very long blades on the CFM56.

Clandestino

28th Mar 2013, 22:21

.fly the wings off a plane...it is an expression...And there I was, believing we are supposed to be discussing exact science of aeronautics here, not belles-letres.

.and if you fly the wings off the plane as your wheels touch the ground, you have lost your wings, but saved your passengersFor that, you have to perform touchdown at the bottom of the loop at 3.75G, provided aeroplane was certified with zero structural margin above minimal required. Also high lift devices need survive load 25% above maximum required for certification and landing speed at least 49% above Vref. That would stretch credibility even in a trashy movie.

high bypass vs lower bypass...think about it..Yukla 27 had low bypass fans. No need to think further.

Anyway, does anyone have a proof that AA742 really had control problems?

bubbers44

28th Mar 2013, 23:40

Looking at the momentary slight climb around 100 ft the touchdown would have been better without it but looking at the video of the touchdown they did a fine job. Who else has done a better job of landing in the Hudson in a jet with no engines?

bubbers44

28th Mar 2013, 23:45

AA742 as I recall was a minor autopilot malfunction easily over ridden by competent pilots.

Ashling

29th Mar 2013, 00:24

Bubbers, sorry not good enough, you are truly myopic.

bubbers44

29th Mar 2013, 01:02

myopic means you can only see things close, right?

bubbers44

29th Mar 2013, 01:04

myoptic? Is that what you meant?

bubbers44

29th Mar 2013, 01:23

We all know Sully is a hero so if he leveled and climbed slightly at 100 ft, so be it, he did a great job of saving those people and thank God he was the captain with a competent FO helping him. They saved the whole flight from disaster. We need more of this quality of pilots to be flying our airlines today, not button pushers.

misd-agin

29th Mar 2013, 01:27

No flight control problem. Some sort of flap disagree light. It went out.

The engines didn't produce power because of damage to the engine core. The size of the fan(N1) has nothing to do with the accident if the bird goes into the engine core. The size of the core inlet between engines producing similar thrust is minimal.

bubbers44

29th Mar 2013, 01:46

Let Sully have his glory because we wouldn't want to do what he did but hopefully could. Could you? I think so.

sevenstrokeroll

29th Mar 2013, 02:25

clandestino...except I remember a nice story where the wings collapsed shortly after landing...the spar had broken in flight, the pilot heard it break and got on the ground in one piece...the plane was an A26 I think.

and again, if the target is smaller and the bird DOES NOT get in, then aren't you better off?

now, go play in the traffic!

sevenstrokeroll

29th Mar 2013, 02:34

misd...and who says they have to produce the same thrust?

the engine inlet on an MD80 is smaller than the inlet on the airbus 320 (cfm)...yet they do about the same thing on the stage length involved.

the point is avoiding the bird in the core.

bubbers44

29th Mar 2013, 04:42

SSR, I think looking out the windshield and avoiding bird strikes is not taught much any more because of the button pushing technology. I retired about that time so I was able to just turn away from the flocks and avoid them. Now they are too busy programming the computer to see them.

Clandestino

29th Mar 2013, 07:50

the plane was an A26 A26 is not passenger transport aeroplane. It is built to different specs for different kind of mission so some things that worked on Invader are not necessary applicable to Airbus

if the target is smaller and the bird DOES NOT get in, then aren't you better off?Already answered a couple of posts before:

The size of the fan(N1) has nothing to do with the accident if the bird goes into the engine core. The size of the core inlet between engines producing similar thrust is minimal.

misd...and who says they have to produce the same thrust? There is no way to wring out similar performance for similar weight if thrust is not similar.

the engine inlet on an MD80 is smaller than the inlet on the airbus 320 (cfm)...yet they do about the same thing on the stage length involved.

the point is avoiding the bird in the core. The point is: for difference in inlet sizes there is no significant difference in core diameter. Target area is the same for JT8 or CFM56.

SSR, I think looking out the windshield and avoiding bird strikes is not taught much any more because of the button pushing technology. I retired about that time so I was able to just turn away from the flocks and avoid them. Now they are too busy programming the computer to see them. It would be helpful if anyone would provide reference to which airline, when and especially how taught their pilots to maneuvere their jet transport to avoid birdstrikes.

No flight control problem. Some sort of flap disagree light. It went out. Thanks, it confirms my suspicion that incidents where manual flying ineptitude played part are so rare we have to invent them to keep "pilots of today don't know how to fly" line of discussion alive.

Ashling

29th Mar 2013, 08:49

Bubbers no one is disputing that Sully and his crew did a great job overall however that is no reason not to learn lessons.

You have roundly criticised others for poor handling skills, well Sully got 19 kts slow on ref and entered a stall protection mode. This led to a harder splashdown than would have occurred had he flown the correct speed. If you criticise others for poor handling skills but fail to acknowledge that error then you lack professional integrity.

You might also like to note that all those wonderfull pilots of years gone by whose handling skills you so elevate had a nasty habit of flying aircraft into terrain and not relating so well to the crew around them. Aviation today is safer because those lessons were learnt. So today's button pushers crash less than yesterday's aces. Go figure Bubbers.

There are major lessons to learn today and AF447 and other incidents do indeed point to a lack of basic airmanship and handling skills. However it is way too easy to blame individuals.It is a systemic problem that allows people with inadequate training and experience to occupy the seats and also an arrogance that the aircraft are so well designed that they do not need to train pilots as rigorously as they once did and as we know the commercial pressure of paying people too little so that they cannot afford to live leads to pressure and fatigue.

To its great credit the USA is trying to do something about it as it now appreciates after Colgan and the Hudson the value of having a Sully in the seat. My country, I am afraid and much of Europe seems to still have its head buried in the sand from a regulatory point of view.

Capn Bloggs

29th Mar 2013, 11:23

It would be helpful if anyone would provide reference to which airline, when and especially how taught their pilots to maneuvere their jet transport to avoid birdstrikes.

It'll be the same one that provides collision-avoidance training when encountering an unknown VFR in Class E airspace. Or do you just hang on and hope for the best, like when you spot a big flock of Canadian Geese in your 12 o'clock at a couple of miles?

Clandestino

29th Mar 2013, 12:47

It'll be the same one that provides collision-avoidance training when encountering an unknown VFR in Class E airspaceErrmmm.... are you aware of the size difference between this one:

http://www.repmanblog.com/.a/6a00d8341c39e853ef01116858409d970c-pi

and this one:

http://www.copterplane.net/wp-content/uploads/2012/03/Cessna-172.jpg

For those uninitiated, pictures are not to the same scale.

Or do you just hang on and hope for the best, like when you spot a big flock of Canadian Geese in your 12 o'clock at a couple of miles? In real world, flock of Canadian geese is very small target hard to spot form a couple of miles unless they have large angular movement relative to observer so are to far away from the flightpath to present any hazard. Until someone proves otherwise with official document, I'll bin "Methods of visual acquisition of birdstrike hazard and its mitigation through maneuvering passenger transport aeroplane at low speeds and low level" into fanciful rubbish folder.

Has PPRUNE really degenerated to people advocating the reintroduction of low bypass engines to mitigate the risk of a birdstrike? Yup. While it is a good thing to be open to new ideas, we must never accept them without scrutiny. This one has been demonstrated to be false and useless yet it lingers on, but then it is not the only such around here.

There are major lessons to learn today and AF447 and other incidents do indeed point to a lack of basic airmanship and handling skills. Correct, but...

However it is way too easy to blame individuals.Aeronautical accident investigation is never concerned with laying blame. All it is interested in is how do we prevent accidents from recurring and for that we have to understand what happened and why it happened.

Eventually, it was sum of inadequate individual performance that doomed AF447. There was no R in CRM to manage. Investigation of other incidents that started just like AF447 uncovered very serious lack of understanding of UAS procedures among crews, but as in aviation we have safety layers piled upon safety layers, such widespread ignorance turned out to be fatal just in conjunction with paradoxical pull up reaction and ignorance of stall warning from both pilots simultaneously.

It is a systemic problem that allows people with inadequate training and experience to occupy the seats and also an arrogance that the aircraft are so well designed that they do not need to train pilots as rigorously as they once did and as we know the commercial pressure of paying people too little so that they cannot afford to live leads to pressure and fatigue.Problem is indeed systemic but what we are looking for is competence, with training and experience just being means of achieving it. That experience is necessary has been successfully disproved by companies successfully running cadet schemes last couple of decades and sometimes folks with wrong kind of experience (such as long history of successful minima busting) can be liability in cockpit.

As for arrogance of the manufacturers, legally they are not responsible for the training provided to those who fly aeroplanes they've made; operators, training organizations and aviation authorities are. Manufacturers can set minimal training required and say: "We fond out this works with our pilots, if you think you have same quality pilots as we do, you can take it as your training syllabus but responsibility is entirely yours".

Commercial pressure is not just manifested in remuneration, more and more pilots are contractors, responsible for financing their initial and recurrent training and tend to go for shortest and cheapest options. Given current rates, I can't blame them for it.

To its great credit the USA is trying to do something about it as it now appreciates after Colgan and the Hudson the value of having a Sully in the seat. My country, I am afraid and much of Europe seems to still have its head buried in the sand from a regulatory point of view. It's politicking on both sides of the Atlantic. I suspect insisting just on experience while leaving training, checking and employing as it is will do as much good as doing nothing at all.

Capn Bloggs

29th Mar 2013, 13:10

Errmmm.... are you aware of the size difference between this one:

Totally irrelevant. My comment was based on manually avoiding something you could see. Keep up will you?

sevenstrokeroll

29th Mar 2013, 14:00

to all, esp clanestino.

From the real world...see and avoid. Again, not from the world of computer games/simulators.

Things I have spotted with time to maneuver... At FL350 in the vicinity of Los Angeles, CA, USA. A child's balloon with the Mickey Mouse Insert. Speed in excess of .80 mach.

Many times I've seen a flock of birds, including canadian geese in the vicinity of both LGA and DCA.

All see and avoid can be enhanced by ''scanning'' with purpose and allowing the eye to focus beyond the end of your nose.

AS far as the A26, it was used as an executive transport after WW2. And a plane is a plane, unless you specifically exclude the airbus.

There seems to be an amazing problem with the idea of engine core and fan inlet. IF the bird can't get into the core because the inlet size is smaller, don't you prevent the damage?

And high bypass engines are not without their problems...while a bit more efficent, one wonders at what point the benefits of efficency are overcome by the facts of aviation life.

High bypass, wing mounted, underslung engines are very good at wing bending relief, and sucking ground workers into the engine. And will someone tell me a western medium or low bypass engine that ingested birds and forced a ditching?

The only true way to test my theories is to fly planes through flocks of birds. I vote that clandestino fly the airbus through the flock, using his knowledge. I'll fly a DC9 series through the same flock using my knowledge.

Loser has to wash both planes by hand.

(oh, and one more thing about airlines teaching visual scanning and maneuvering...I recall in all the ready rooms of my airline a marvelous series of diagrams showing how to SCAN for traffic of any kind, including birds...perhaps some of you remember it showing the size of a dot in the windscreen, eventually manifesting itself in a T33. A non moving dot on the windshield is either an unlucky bug or a potential head on collision...so yes clandestino, some of us know how to SEE...try it some time)

Machinbird

29th Mar 2013, 14:34

In real world, flock of Canadian geese is very small target hard to spot form a couple of miles unless they have large angular movement relative to observer so are to far away from the flightpath to present any hazard. Until someone proves otherwise with official document, I'll bin "Methods of visual acquisition of birdstrike hazard and its mitigation through maneuvering passenger transport aeroplane at low speeds and low level" into fanciful rubbish folder.
As one who has routinely seen and avoided birds of the same size (turkey buzzards) while leading a formation of aircraft, I'll conclude that you probably do a lot of head down work in the cockpit and have not really thought about what visual techniques to use to pick up these "soft" targets.

With sufficient visibility and suitable background, the big birds do stand out visually. You simply have to make the effort to look for them and to be mentally prepared to react. The earlier you spot the birds, the less you need maneuver to avoid them.

I'll withhold judgement on last second impact minimization maneuvers.

JW411

29th Mar 2013, 17:22

I have lost count of how many birdstrikes that I have had in my long career. I have to say that I have managed to avoid a collision on several occasions but only when flying a light aircraft or a glider. A lot of those events were probably purely down to pure luck.

I have never managed to avoid a birdstrike in a big aircraft. I suspect that the lack of relative manoeuverability and the slow control response has a lot to do with it.

At the risk of boring everyone, the largest birdstrike that I ever had was when I hit a sea-eagle (7 foot wing span) on finals to a famous middle-east island airfield whilst flying an Argosy. It hit the starboard leading edge and flattened and ripped the D-box open right back to the main spar.

We were there for several days whilst repairs were carried out. Now it turns out that sea-eagles are monogomous so every time we looked out of the bar, the partner was circling outside looking for her mate who was never going to come home.

Very sad.

misd-agin

29th Mar 2013, 19:44

SSR- The compressor inlet is ridiculously small. It's a matter of inches wide.
The size of the N1 doesn't matter in the Sully incident. The birds went into the core.

Ashling

29th Mar 2013, 22:29

Clandestino

I agree with much of what you say, re my quotes, if I understand you correctly. Much of aviation has adopted the "Just Culture" so, as you say, it's about looking at the causes and lessons to be learnt. Or should be.

I'm not entirely sure that the recent trend of recruiting inexperienced crew has disproved the need for experience or, to be more accurate, a balanced recruitment policy. Aircraft are so reliable now that they can mask many of the pilots failings and its only when the unexpected happens that that lack of experience coupled with inadequate training comes home to roost. AF447 and many other incidents. The lack of RHS experience also puts great pressure on the LHS occupant who flies with them day in day out. It's interesting to note that one LCC is changing its recruitment policy from one of cadets only to a cross section of backgrounds.

Of course in the old days we had much more opportunity to handle aircraft manually but we also tended to stuff it up,every now and then, and crash. So they increased automation and safety systems to address this. The end result is safer but at the expense of basic handling skills. That was okish because we had a background in the forces or came through the self improver route so we had a base of experience to fall back on. The way LCCs have used the cadet system has changed that so its a double whammy, not much in the way of handling experience and in the RHS of a commercial jet airliner that gives no opportunity to develop those handling skills.

There's nothing really new in all that and plenty have warned about it for some time. We can only hope that the politicking stops and they address it properly. A naive hope I fear.

bubbers44

30th Mar 2013, 00:12

I think any pilot with a brain cell could turn away from a flock of birds. If you can't then so be it. I have done it hundreds of times but it if you can't then find another profession. Flying into TGU honduras we always avoided flocks of turkey buzzards. Not by bs but just looking out the window.

CONF iture

30th Mar 2013, 02:51

As long as I am commander, anyone truly believing that couple of degrees more of alpha when it is already over ten can improve touchdown has no business occupying any seat from which flight controls can be reached.
Sully was the captain on that 320 and tried to do just that ... I wish you would have taken control from him my Commander.

NTSB report clearly shows speed was too low.
NTSB report clearly shows the potential to reduce the vertical speed at touchdown but how the system prevented the pilot to proceed.
Time to bring up your data that contradict the NTSB now.

Lord Spandex Masher

30th Mar 2013, 09:19

Ashling

30th Mar 2013, 09:40

You get it the wrong way round.

The primary reason they had problems with the flare was that they allowed their speed to decay upto 19 kts below ref. That caused them to enter Alpha Prot which then attenuated their inputs. Any pilot should know that flying 19 kts slow is not the way to glide an aircraft, to flare effectively you need energy so that you have nose authority. Any Airbus rated pilot ought to know the consequences of entering Alpha Prot would be deeply undesirable at any time but doubly so at 150 ft engines out.

Don't blame the aircraft for a situation the pilot put it in.

Now it's a matter of fact that he got slow and I assume that you don't dispute that. I also assume that you accept flying that far below ref is not the correct way to glide an aircraft. If not then there is no point discussing it further.

That then brings us to why. Was Sully just unaware of his actual speed or did he deliberately fly that slow. If its the former, the view of the NTSB which I agree with, then clearly it's down to task saturation and the pressure of the situation. Something we can all identify and accept. We wonder if we could have done as well as Sully and note the need to pay close attention to speed control. If its the latter then he would have been very foolish indeed and that's being generous.

Now having placed the aircraft in that undesirable position you are quite correct, the aircraft did attenuate his inputs. Was there a margin to the stall, yes again you are correct. At splashdown Alpha Max was 17.5 and the left AoA vane had him at 14.5 while the right had him a touch over 13.5. The trace corrected for pressure altitude and airspeed hits a peak of 16.5.

As you rightly state, Alpha Max is not Alpha stall. I think the gap is 3 degrees or so.

So depending on which vane you take or if you accept the pressure altitude value they had anywhere between 1 and 4 degrees spare to alpha max or 4 to 7 degrees spare to the stall. There is a margin but in terms of speed it would be a few knots. It might make a small difference but not much and if the pilot gets it wrong and stalls then utter disaster occurs. At the corrected figure there is stuff all margin.

If you took Alpha Prot away Then of course you would have to consider the handling characteristics of the aircraft. The controls would have been sloppy and the pilot would never have flown the real aircraft in that regime. The aircraft may have a tendency to pitch nose up close to the stall compounding things ( longitudinal stability or as Airbus state Phugoid)

That's why Airbus put the protection there. They designed the aircraft, and know how it handles. It's not just about a few knots of speed or a couple of degrees of alpha it's about handling characteristics including longitudinal stability. That's why Alpha Prot attenuated the pilots inputs which can be as aggressive as he or she likes with no risk of stall.

Never forget that the aircraft gave Sully the max performance it could even though it didn't get to Alpha Max.

So all in all was there a margin, yes a small to very small one, could he have taken advantage of it had he been able, maybe but it would have been edgy to say the least and the downside would have been catastrophe so in my view it would have been foolish to do so.

In essence Sully would have had to outperform the FBW to do any better, given that the FBW max performed and we know from other data that pilots don't routinely outperform FBW I don't think it would have been realistically possable for him to do so especially given the workload and pressure he was under. After all he let his speed decay in the first place.

Confiture, I accept you take a different view, others can judge the merits of out varying points of view, just please don't blame the jet for a situation the pilot put it in in the first place albeit under huge pressure.

FDR refs are taken from the NTSB's Group Chairman's Aircraft Performance Study. I published the link earlier if you look back. It's post 147.

Capn Bloggs

30th Mar 2013, 10:37

think any pilot with a brain cell could turn away from a flock of birds. Is Sully a bit short on brain power then?
Nope. He didn't see them.

Clandestino

30th Mar 2013, 10:53

Lord Spandex Masher

30th Mar 2013, 10:55

Ah, so number of brain cells is irrelevant then.

I wonder how many turkeys our hero Bubbers didn't see.

DozyWannabe

30th Mar 2013, 16:35

I don't think the personal mudslinging's helping any here. We know bubbers likes to throw the cat among the pigeons by throwing out a contentious statement here and there - I doubt whether he actually believes some of the things he says, but I do think it's worth it for the entertainment value.

Anyways - we know that "see and avoid" has been considered insufficient for high-density airliner ops since the '50s, and there's no question of relying on it any more than necessary - smoking holes in the Grand Canyon, North Park and Cerritos are testament to that fact.

The Hudson ditching following a birdstrike was about as successful as result as anyone could hope for. We know they had to stretch the glide in order to avoid bridges, and doing that was far more important to the success of the attempt than fitting into Airbus's criteria for ditching on water. Talk of flare optimisation is ultimately little more than a distraction attempt - by people with an agenda, wanting to make something out of nothing.

Machinbird

30th Mar 2013, 19:17

How come that real life pilots don't see the birds they are about the hit and yet PPRuNe is full of experten that avoided many a bird through timely observation and decisive maneuvering in their passenger jets or while leading fast jet formation? Fair question. The reason is simple. Normalcy bias in the execution of one's scan. Also, most pilots have not considered what type of scan is required to detect birds and never develop an anti-bird scan.

The scan to detect birds is different than the one used to detect intruding aircraft, and the anti-bird scan requires additional effort. After 100 flights and no birds sighted, you relax your anti-bird scan and do not even realize you have done it.

So, what type of scan is required to detect birds? First, remember that birds are very slow in comparison to your jet/turboprop aircraft. You do not have to detect all birds in your vicinity, only those that are a collision threat.

Visually, the zone of potentially hazardous birds is in close proximity to your flight path vector. That is the area requiring extra scrutiny for birds. Assuming normal pilot visual acuity and a suitable background, you will be able to see large birds beyond 1 nautical mile. You need to pause your general visual scan and concentrate on the small area of the windscreen around your flight path vector and look for tiny dots that are circling or flapping wings. This will require about 2 seconds. Then resume your navigational & collision avoidance scan. Repeat.

When to expend the effort on anti-bird scanning? Although there have been rare high altitude bird collisions, the probability of successful detection is low. The risk/reward ratio doesn't make sense.

My personal rule of thumb was to start anti-bird scanning below 10,000 feet AGL and intensify the effort as we descended. If you routinely fly into an area that has bird concentrations, it pays to study that area's bird hazards and learn the hot areas for bird-aircraft interface. Until you dirty up, you should be able to easily maneuver above any visually detected birds. Once you dirty up, you have fewer options, mostly turn and climb to avoid type maneuvers.

It is crucial that you respond quickly to threats. If you have to think about how to disconnect the A/P then you aren't ready for bird encounters. Better yet-hand fly in high bird threat areas.

The above is my take on bird avoidance based on personal experience. I never struck large birds. I have come back with red streaks on the aircraft from small birds that I never saw.

sevenstrokeroll

30th Mar 2013, 20:18

Now I see the problem. The problem is that some here think flying is a science. While there are many scientific aspects to flying, I am convinced that flying is an art as well. Someday that art might be scientificaly explained...but just as the master painters were artists, we can only slightly appreciate the science of their ways.

Some of us have dealt with birds and haven't had to land in the Hudson. yet science has not dealt with the birds in such a way as to reduce the problem.

So, with science's help, I encourage the ART...and good luck with that. Art will take experience and can't be programmed into a computer...yet.

I do take some exception to what has been said here. While I haven't taken my tape measure to the intake of the JT8D and the CFM56...the CFM56 sure appears to have a larger intake. It also seems to have less "stuff" in the intake to upset a bird hell bent for the engine core.

Granted, any bird that gets to the engine so much as to disrupt the compressor and even the turbine section is going to cause problems, but the idea is to not let the giant bird into the engine...

Putting the large intake CFM56 in front of the wing allows an easier path for a bird to get into the engine than putting the small intake JT8d behind the wing on the fuselage.

I am not saying its impossible to get a bird in to the rear mounted engine, just a bit harder.

Now you scientists, go out and fly the planes through the birds and let me know. And please remember that a molecule of ''air'' is not the same as a big canadian goose.

I think bubbers and the others who have actually dealt in a high bird environment do know what they are talking about.

I also think that maybe if sully and skyles didn't have so many ''dials'' they might have been looking out the window more and finding the birds a bit sooner. Now, I'm not blaming them, more attempting to call things to the attention of airplane designers.

There is a discipline in looking for aeronautical hazards. And New York is very distracting...especially on a nice day.

Pitch Attitude is important too. Anyone have the exact airspeed the plane was traveling/indicating at the moment of bird strike. perhaps some of you artists will see what I am about to get ''at''.

Lord Spandex Masher

30th Mar 2013, 21:01

JS, what these old stick in the muds fail to realise is that there are not as many dials in a modern flight deck as they were used to back in the day. Therefore, by their definition, we don't have as many bird strikes because we spend all day looking outside.

Despite that, of the couple of dozen bird strikes I've had, not once did I see the bird in enough time to avoid it...and I'm a heads out sort of a guy.

DozyWannabe

30th Mar 2013, 21:28

Now I see the problem. The problem is that some here think flying is a science. While there are many scientific aspects to flying, I am convinced that flying is an art as well.

It's not an either/or proposition - as with most things in life there are aspects of both.

While I haven't taken my tape measure to the intake of the JT8D and the CFM56...the CFM56 sure appears to have a larger intake. It also seems to have less "stuff" in the intake to upset a bird hell bent for the engine core.

The JT8D sure can suck in a lot of ice though - with tragic results:

Southern Airways Flight 242 - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Southern_Airways_Flight_242)

Putting the large intake CFM56 in front of the wing allows an easier path for a bird to get into the engine than putting the small intake JT8d behind the wing on the fuselage.

True, but podded, wing-mounted engines have among their advantages ease of maintenance, and crucially in today's all-hydraulic airliners allow a greater degree of control through differential thrust than their tail-mounted counterparts.

Your devotion to the DC-9 is admirable, but like it or not, things have moved on.

JS, what these old stick in the muds fail to realise...

While I share some of your frustration, the personal stuff is not helping...

Lord Spandex Masher

30th Mar 2013, 21:33

It's not personal. Stick in the mud is a descriptor for people who appear not to like the product of progress.

DozyWannabe

30th Mar 2013, 21:39

I'm not contesting the appropriateness of the description, I'm questioning the wisdom of using such language when it's likely to get people's hackles raised! :)

Lord Spandex Masher

30th Mar 2013, 21:46

I've never claimed to be wise;)

Clandestino

30th Mar 2013, 22:11

True

False, DC-9 engines are not behind the wing, they are above and behind it. That any civil turbofan engine needs access to clear, undisturbed air to work properly and therefore cannot be protected from any flying FOD is hard scientific fact that cannot be altered by surrealist, dadaist or any similar art movement. Perhaps if we use cubist perspective, then indeed they are shielded by wing or fuselage or whatever but while cubist paintings brought fame and money to certain Spaniard, no draftsman that has drawn cubist blueprints has ever landed a job anywhere.

Seemingly in the race to air most implausible theory in this thread someone has conveniently overlooked that I have already mentioned catastrophic failure of western built low bypass engine following ingestion of geese but then I don't expect folks with very chivalrous attitude towards reality would know what Yukla27 was or would look it up.

Interestingly, for all the fuss about birdies here ASN lists only 56 events severe enough to be mentioned (http://aviation-safety.net/database/dblist.php?Event=COOB), most of them non-fatal, if we count only humans, that is.

DozyWannabe

30th Mar 2013, 22:35

@Clandestino:

You're right, but seeing as we're dealing with hypotheticals here, strictly speaking the difference in engine placement may make a difference, and I'm happy to give sevenstrokeroll the benefit of the doubt. That said, we're way outside the original topic and I'm beginning to wonder just what the point of this meandering is!

bubbers44

31st Mar 2013, 01:36

No, sully had a very good brain to put it down as professionaly as he dd.

bubbers44

31st Mar 2013, 03:09

Probably missed some but over 90% we saw by looking out the window.

Capn Bloggs

31st Mar 2013, 03:34

podded, wing-mounted engines...crucially in today's all-hydraulic airliners allow a greater degree of control through differential thrust than their tail-mounted counterparts.
"Crucially"? You're pulling my leg, surely! Are you seriously saying that this was a consideration in the placement of engines on the wings? Quite apart from the over-sensitive reaction to a tiny bit of asymmetric power, the pitching moment of underwing engines makes them far worse in a control-by-thrust scenario than tailmounts. Desk-jockey nonsense.

we're way outside the original topic and I'm beginning to wonder just what the point of this meandering is!
You can say that again!

DozyWannabe

31st Mar 2013, 07:35

"Crucially"? You're pulling my leg, surely! Are you seriously saying that this was a consideration in the placement of engines on the wings? Quite apart from the over-sensitive reaction to a tiny bit of asymmetric power, the pitching moment of underwing engines makes them far worse in a control-by-thrust scenario than tailmounts. Desk-jockey nonsense.

Think what you like, but I'm sure it was at least one of the considerations involved. Yes, podded engines mounted under the wing give a pitch-up moment, but there's no denying that as long as that is compensated for, one can get a greater effect on the yaw axis from engines mounted in that manner - it's just basic physics.

Of course, the main reason T-tails with fuselage-mounted engines went out of fashion was the inherent problems with deep stall in that design configuration, but other considerations were undoubtedly involved.

Capn Bloggs

31st Mar 2013, 08:37

Yes, podded engines mounted under the wing give a pitch-up moment, but there's no denying that as long as that is compensated for, one can get a greater effect on the yaw axis from engines mounted in that manner - it's just basic physics.
This is getting more ridiculous as time goes on. Why do you think you're using thrust vectoring? Because the normal flight controls don't work! You can't "compensate" for the pitchup if don't have any other means of pitch control. Oh hang on, we've got a totally jammed roll/rudder system but a controllable stab/elevator. OK, now I understand...

the main reason T-tails with fuselage-mounted engines went out of fashion was the inherent problems with deep stall in that design configuration, but other considerations were undoubtedly involved.
Designed right, it won't. The real reason was/is weight and balance.

Clandestino

31st Mar 2013, 09:26

Much of aviation has adopted the "Just Culture" so, as you say, it's about looking at the causes and lessons to be learntCorrect. It useful too keep in mind that reason for applying just culture is purely pragmatic: it helps us to learn from others' mistakes that would be swept under rug in punitive culture and so makes flying safer. It is not there to cater for someone's increased sensibility and is definitively not get-out-of-jail-free card.

I'm not entirely sure that the recent trend of recruiting inexperienced crew has disproved the need for experience or, to be more accurate, a balanced recruitment policy.I am afraid current aviation policies (not just recruitment) will eventually end up in disaster and when it happens, there will be plenty of old hands whose battle cry "More experience in cockpit!" will be picked up by politicians. IMHO it would be wrong.

The myth experience=quality comes from general aviation. As it is usual with myths, it begins with something substantially true but eventually a bit of embellishment and misapplication here and there gives us something useless for all practical purposes yet considered to be holy writ (e.g. stalling when turning downwind). In general aviation, unfortunately, experience is often the only way of acquiring skills and knowledge. It is not so in structured training environments where there is ample opportunity to teach pilot everything he needs to know and verify whether he is able to apply the learnt but what is extremely important and often overlooked, even before the training starts, air force or airline have the opportunity to select those brightest, aptest and the most motivated to eventually fill the seats. I think shrinking the candidates' pool is that's the area that will hurt us most in the long term. Western airlines are more and more laying training costs on individuals while offering pretty unattractive T&C so those most suited to become a pilots will be far better off in some other walk of life. Whether those who beat financial besides training obstacles and get installed into front seats will be good enough remains to be seen.

Aircraft are so reliable now that they can mask many of the pilots failings and its only when the unexpected happens that that lack of experience coupled with inadequate training comes home to roost.'Tis an old cliche that flying is 99% of boredom punctuated by 1% of sheer terror and pilots are paid for coping with that 1%. Problem with idea that lack of experience causes accidents is that very old hands have flown their aeroplanes into mountains or were unable to perform simple task such as: if ASI doesn't work, reject takeoff. Also some pretty new pilots coped with emergencies successfully. While experience does make a better pilot, it is not always so and it isn't only way of making a good pilot. When proverbial hits the fan, pilot quickly needs to know what happened, what he needs to to and to perform it as perfectly as possible. With todays aeroplanes most failures are now not once-in-a-lifetime but once-in-20-lifetimes events so one has to learn from others' experience. Capt Sullenberger was very inexperienced in A320 ditching, which didn't prevent him from pulling it successfully the very first time he made it.

The lack of RHS experience also puts great pressure on the LHS occupant who flies with them day in day out.Again, it is competence, not experience and I'd say enthusiasm towards work and flying is better indicator of one's capability than hours in logbook.

It's interesting to note that one LCC is changing its recruitment policy from one of cadets only to a cross section of backgrounds.Being jaded cynic, I'd suggest it's because they couldn't find enough bodies to fill the seats.

Of course I'm wrong. They are fully committed to safety and all their policies and actions reflect so.

Of course in the old days we had much more opportunity to handle aircraft manually but we also tended to stuff it up,every now and then, and crash. So they increased automation and safety systems to address thisWith idea we won't get tired of constantly fling and so will be fresh to takeover when George packs up so we can work longer and weirder hours. Also I blame the unions of yesteryear for not redirecting the pay of F/Es that were made redundant to pilots - after all we are now doing their job when all the automatic systems niceties fall apart.

That was okish because we had a background in the forces or came through the self improver route so we had a base of experience to fall back on. Peacetime forces pilot is very desirable and very rare post so forces can be picky and choose those best suited for the job. It is oft the quality of raw material, not the experience that makes the difference. As for the self improvers, while they are mixed lot I admit most of them are maintaining strict self-discipline while having the holy grail of airline seat in sight. There are some things applicable to Pawnee that are useful in 320, there are some that are not. As long as one can tell which is which, he'll be fine.

The way LCCs have used the cadet system has changed that so its a double whammyExactly. Cadet scheme is generic term, we have to be careful to avoid painting everything with same brush.

We can only hope that the politicking stops and they address it properly. A naive hope I fear. I am afraid that politicians of today have only two modes: passivity and panic reaction and I can't tell which one is worse.

sevenstrokeroll

31st Mar 2013, 14:14

first, why did I write "DIALS"? I wrote it because it rhymed with SKYLES, the copilot's name. What I meant is that there is more button pushing and head down time in a an airbus than older types.

And mounting engines on wings in pods...now I had more laughs out of this one than just about anything. Its more a structures thing than to use assymetric thrust for yaw or pitching. Oh and by the way, if you have engines on the wings you need more of a vertical fin/rudder.

And deep stalls have been mitigated by easy aerodynamic fixes like vortilons.

and once again clandestino does not understand an air molecule is different than a goose.

consider the goose, flying along thinking gooselike thoughts...hmm, look at the empenage on that gander and bam, gets sucked into an engine.

or

what is that big silver thing coming at me...bam hits the fuselage, or even better yet...oh, I'll dive below that big silver thing.

sorry clandestino, you are not accounting for other things than airflow....oh and I asked a question about airspeed/pitch at time of bird strike...still waiting for an answer on that one.
clandestino, the engine is not fully protected in a rear mounted plane...but even you, the master quoter must acknowledge that if the engine has nothing in front of it like on the 'bus there is NO chance of anything getting in the way of the bird, except the engine

and putting the engines on the tail at least gives a chance for a bird to hit something else than the engine first.

and that bit about a once in a lifetime event ...what skills did sully use in ditching the jet? wings level, maintain flying speed, touchdown ...oh yeah, we do that on most landings, don't we? sure if there is a X wind, we throw in some crab and maybe even wing low, tut, tut, the basic skills of any ditching are practiced on every flight.

as far as ''sucking ice'' and the JT8d. It wasn't ICE it was HAIL (although hail is frozen too). And I recall a TACA 737 with cfm's having to land on a levee and it only SUCKED RAIN.

The HAIL oblitered the windscreen too,making an off airport landing more difficult.

Sucking HAIL can be avoided by adjusting wx radar and knowing a possibility of hail exists.

sevenstrokeroll

31st Mar 2013, 14:22

oh, and the devotion to the DC9 is respect. After seeing the way the airbus has done, I have even more respect for the 9 than ever before...KISS.

oh and for those who don't know what KISS means, its Keep It Simple, Stupid.

Owain Glyndwr

31st Mar 2013, 14:58

Interestingly, for all the fuss about birdies here ASN lists only 56 events severe enough to be mentioned (http://aviation-safety.net/database/dblist.php?Event=COOB), most of them non-fatal, if we count only humans, that isJust for the record, 21% of these were jet/turbofans on the wing, 34% rear engines and 45% propeller driven. Not much evidence there that rear engines are less susceptible to bird strike.

Ashling

31st Mar 2013, 15:00

Clandestino, a couple of thoughts

You are of course quite right, experience does not always equal quality just as inexperience does not always equal incompetence.

I was always amazed at just how quickly the RAF turned me from zero to hero (well perhaps not quite).

However as you also say they had their pick and it was/is a highly supervised environment even after you exit formal training which means that if you put the effort in you develop rapidly. If you don't put the effort in you tend to get binned or sidelined until you mend your ways.

Its about selecting the right people and giving them the right training and the right development and supervision when they are qualified. Sadly it would seem that some organisations may be more interested in ability to pay than they are in aptitude. This is especially true when the Loco's are demanding more pilots, the quality of the product gets diluted. I've certainly feel that I've seen a reduction in standard over the last 10 years or so. Certainly line training is much more stressfull as is sitting in the LHS.

In my view airlines training systems are not set up to develop large numbers of low hours pilots effectively. You can do it, just not with the current set up. It works ok for restricted numbers of high ability individuals though and thats why a balanced recruitment policy is still best in my view. It also good to have a variety of backgrounds as the whole thing tends to get a bit incestuous otherwise. The airline I referred to that is changing recruitment policy isn't doing it because there aren't enough cadets banging at the doors, far from it, its for other reasons but I'm not in the know so can only guess at why.

Experience doesn't solve everything but it helps and you are quite right to observe that the attitude of the individual is key. That is true at any stage. Much better an able, keen, hard working pup than someone with thousands of hours who does the minimum. However most do put the effort in.

Sully coped, in my view, because he was an able indidual who had a wealth of experience to fall back on. In the crucial seconds after they hit the birds he got all the big calls right and that set them up for a successfull outcome. I can only hope I could have done the same but equaly pray I never have to find out. I also believe that a number of the relatively inexperienced commanders we have would have coped just as well, some better. But for me if you had a 100 Sully's v 100 new ex cadet commanders in the same scenario the Sully's would have a significantly higher success rate. Sadly Sully's are a dying breed.

Whichever way we slice it, and I'm not pretending my view is the only/right one, we have a problem and have had for some time.

bubbers44

31st Mar 2013, 15:02

Clandestino, I don't think any airline has sop's on avoiding birds, they assume you will not run into other airplanes and birds when they hire you. You avoid other airplanes by looking out the window, just as missing birds and mountains. When you drive your car do you just stare ahead at your lane or do you check to make sure cross traffic isn't running a red light? I use the same techniques in an airplane to try not to hit anything. Remember that idiot in LA that tied balloons to his lawn chair and took to the skies? Now I even look for flying lawn chairs.

sevenstrokeroll

31st Mar 2013, 16:02

owain...how many of the rear mounted (western) jets had to ditch?

how many wing mounted had to ditch?

oh and clandestino, by your own statement, the engines on a 9 are above and behind the wing...wouldn't that be more bird resistant to birds approaching from the underwing angle vs wing mounted eng?and wouldn't that be more protective in a plane that is climbing and birds that are level?

sevenstrokeroll

31st Mar 2013, 16:14

I found the ASN report very interesting indeed...NONE of the incidents/accidents included DC9s. none.

con-pilot

31st Mar 2013, 16:46

owain...how many of the rear mounted (western) jets had to ditch?

I know of only one, had nothing to do with bird ingestion; ran out of fuel.

ASN Aircraft accident McDonnell Douglas DC-9-33CF N935F St. Croix, Virgin Islands [Caribbean Sea] (http://aviation-safety.net/database/record.php?id=19700502-0)

bubbers44

31st Mar 2013, 17:29

One of our MD80's had a dual deer strike one night resulting in a high speed abort. Someone put two deer decals on the nose section. One of our pilots had a fish strike at 100 ft landing at OAK when a seagull dropped it when it saw the plane about to hit him. Fish and deer are harder to avoid than big birds.

Owain Glyndwr

31st Mar 2013, 17:30

owain...how many of the rear mounted (western) jets had to ditch?

how many wing mounted had to ditch?What has that to do with the relevant vulnerability of rear and wing mounted engines to bird strike? Nothing that I can see;surely the association of bird strikes with no ditching just reflects the fact that you (generally) meet more flocks of birds overland than over the sea? And of course if the Hudson river hadn't been conveniently close it wouldn't have been a ditching.

BTW, because of the upwash produced by the wing on the flow ahead of the LE, a noticeable proportion of the air going over the wing and towards the rear mounted engines starts below the wing.

sevenstrokeroll

31st Mar 2013, 17:34

con pilot..I know about that ditching...and thanks for publishing it...but I meant due to birds. I know you did too!

and its not that the HUDSON was close...there were other places to go, but with a higher hazard to those on the real brown earth

owain...I have no proof, but the most birds I've seen seem to hang out at the meeting of the land and the water.

Ashling

31st Mar 2013, 17:41

I think listening to ATC + looking at your ND, or equivelant, might also be helpfull in avoiding collisons with other aircraft. It builds SA and helps to avoid TA's and RA's crucial if you have a limited view which you do from the flight deck of an airliner. But, yes, clearly looking out the window is important too, more important at low altitude if GA traffic is around, less important at FL390. Unfortunately the one that is going to hit you tends to be on a constant relative bearing so there is little or no relative movement which of course makes it tricky for the eye as does a low sun and a myriad of other things.

Its a desterate feeling in air combat when the other aircraft has tally on you but you can't see him/her.

Hit plenty of birds too, but still got hired, guess they only assumed I'd avoid other aircraft and mountains which so far I have, still failing on the bird front every now and then. Ho hum.

bubbers44

31st Mar 2013, 19:48

Sully probably doesn't feel as hohum as you do about not being concerned about bird strikes. Go ahead and go to that heads down, who cares what is in front of the window approach. I was heads down getting LAX approach charts out flying a Cessna 340 over LGB when I noticed the lighting seemed different and I was nose to nose with a single engine aircraft. Not knowing which direction he was going to turn I rolled inverted because I had only one move. When he rolled right as he should have I paralleled his wings and rolled with him clearing by about 50 ft. No reports were filed but when he first saw me I was inverted. I wish I could hear his story because probably nobody would believe him. He did the right thing but I wasn't sure he would.

I instructed aerobatics so just pulled back enough to clear him after going inverted. I could pull away more than he could push over. Birds have to be seen to be avoided. Heads down means no bird avoidance so if you are flying into an airport like TGU you need to be heads up because they are in flocks and can easily be seen if you keep your eyes open, not down pushing buttons.

bubbers44

31st Mar 2013, 20:59

I have only one bird strike flying 17,000 hours with the airlines and one instructing. The instructing bird hit the wing causing a dent and the 757 hit above my window leaving TGU. It caused no damage and we saw it but it kept turning with us. If you have multile bird strikes try looking out the window. That is what it is made for.

Lord Spandex Masher

31st Mar 2013, 21:15

If you have multiple bird strikes it's probably too late. Look all you like and avoid all you like but try that going into somewhere like CDG. I'd rather hit a bird than a 747 so 747s are what I'll be looking for.

Try avoiding birds at somewhere like CMF (you'll gather up a hang glider instead or lots of granite) or SIR (you'll just gather a lot of granite). You won't see them anyway, no matter how hard you look.

Try to spot a Thrush against a back drop of the ground at fifty odd feet above the threshold with enough time to decide what you're gonna do and then do it.

Despite the fact that you saw the bird that hit you, you still didn't manage to avoid it! Not a good record to share when you're advocating see and avoid really.

Lord Spandex Masher

31st Mar 2013, 21:17

By the way, how did you see him if you were inverted?!

bubbers44

31st Mar 2013, 21:30

It isn't hard at all. Flying upside down is quite easy once you do it. You push to go up and pull to go down.

con-pilot

31st Mar 2013, 21:33

con pilot..I know about that ditching...and thanks for publishing it...but I meant due to birds. I know you did too!

My bad, beers on me.

I've not had that many bird strikes, maybe about six in 42 years*. Only had one that did any real damage. Hit a seagull (we think) and it managed to hit directly between two LEDs on the right wing (727), had to replace both at the next stop.

But then again, I've never flew a jet with under-slung engines, all have been tail mounted. Which may explain why I never had a bird strike in an engine.

* That includes Midway Island, never had a bird strike there. Why not, I've not a clue, as there are plenty of birds around, trying their best to commit suicide by flying into you.

Lord Spandex Masher

31st Mar 2013, 21:34

You don't say! Doesn't explain how you could see the other guy once you were inverted and pulling away from him.

I'm curious about something else. How many of the birds that you did see (the ones that didn't hit you) were actually going to hit you?

bubbers44

31st Mar 2013, 21:45

LSM,I was not flying, the FO was and his decisions I agreed with. We were at 500 ft and we went opposite our clearance to miss him and the bird turned with us, we reversed to our clearance and the bird turned back, the FO said they always dive and I agreed, he didn't so we did all we could and that is my only airline bird strike. We did everything we could to avoid it but the bird commited suicide.

Lord Spandex Masher

31st Mar 2013, 21:47

So just for clarity you couldn't avoid it despite being able to see it?

See and avoid works does it?

bubbers44

31st Mar 2013, 22:00

LSM, I have no idea how many birds I WOULD HAVE HIT. MY GUESS IS over 6. Most of my check airmen and chief pilots have hit birds and taken them out of service into TGU, I never have in 600 landings. They are occupied instructing and I just have to land so look way out in front. That is how to avoid birds.

Lord Spandex Masher

31st Mar 2013, 22:05

So out of the seven birds that you had a chance of hitting you actually hit one. Which leads me to my other question. How many of the birds that you did see, but didn't hit, were actually going to hit you?

bubbers44

31st Mar 2013, 22:09

LSM, I decided not to respond to your nonsense so goodbye

Lord Spandex Masher

31st Mar 2013, 22:16

Tough questions huh?

How hard is it to answer how many of the birds that you saw (seven of them) were going to crash into you? Sorry, we know about one so what about the other six?

How about the aeroplane that you could see despite being inverted and pulling away from?

Your silence will be deafening.

Clandestino

31st Mar 2013, 23:06

FAA lists 2 dual engine birdstrikes per year. (http://www.avherald.com/h?article=4189d827&opt=0)

Oh, look! There goes CRJ.... and MD80.... and A-10... and Citation...and French Falcon.... and 717. Seems that birds indeed are not air molecules but share common trait of being sucked into engine if they found themselves in front of intake even if it is situated waay back, near the fuselage. But then in the parallel universe where old pilots very experienced in Honduran ops roll inverted their Cessnas 340 to avoid head-on traffic instead of simply turning right, it might be indeed possible to shield the engine intake by the wing or fuselage. Not in our one, I'm afraid.

In my view airlines training systems are not set up to develop large numbers of low hours pilots effectively. Some are, some aren't. I don't have scope broad enough to judge what's the percentage of those who perform their training functions properly but i am pretty sure those who send their cadets up in Citation Jets, Learjets or long Cheyennes have the right idea.

It works ok for restricted numbers of high ability individuals though and thats why a balanced recruitment policy is still best in my view.Problem is with ex-mil pilots supply ever shrinking and general aviation on the verge of extinction (or over it) in some countries, you just can't have balanced recruitment policy and yet you have to match seats with bodies.

Sully coped, in my view, because he was an able indidual who had a wealth of experience to fall back on.Certainly, but I'd add one more contributing factor; capt Sullenberger runs aeronautical consultancy business on the side, so it's not just he can walk the walk.

we have a problem and have had for some time. We do, but it will take a long time to manifest itself in increase of prematurely expired passengers and when it does, it will take ages to get us back where we were even if we promptly do what is right to mitigate it.

Problem, as I see it, are the pilots who know all the books but don't know what they mean. They pass their ATPL multiple choice exams with flying colours. They can do scripted sim sessions all right. They are great in normal ops as they know SOPs pretty well and stick to them. They might get lucky and have successful career without ever coming across the complex emergencies, not covered by ECAM or QRH.

Or not.

Still, their bacon might get saved by the competent pilot occupying the other seat. If they are particularly unlucky to represent typical pilot in their crew, well, they're doomed.

From my, admittedly limited, perspective I'd say their number is still very, very small which anyway presents increase form very,very,very small of decade ago. I mentioned the factors that are working towards their increase in F/O population. Real troubles will start when some less than scrupulous company decides to relax promotion criteria and lets them spill into left hand seat.

Machinbird

31st Mar 2013, 23:21

LSM
Try to spot a Thrush against a back drop of the ground at fifty odd feet above the threshold with enough time to decide what you're gonna do and then do it. Don't worry about the thrushes. They aren't that big. Worry about the cranes, the eagles, the geese, and the vultures and anything else that is big enough to do serious damage.

Your engine is designed to chop up and spit out a thrush. But take evasive action on a flock of starlings if you can. The feathers per second count down the engine may exceed its capacity.:}

bubbers44

31st Mar 2013, 23:22

LSM, it is hard to respond when you make no sense.

bubbers44

31st Mar 2013, 23:30

If you are inverted the windshield still works, just look at the belly of the other airplane and stay parallel with it. Quite simple.

Machinbird

31st Mar 2013, 23:39

I like it when she says, "Do it again".
Yes, but the video is mis-titled. It is an aileron roll.

bubbers44

31st Mar 2013, 23:48

bubbers44

1st Apr 2013, 00:00

If you have less than two seconds you would turn right and hope the other guy does the same thing or do a maneuver that guarantees you will survive? I did the guaranteed maneuver to survive. It worked. If he had turned the same way we would have had a midair collision. I am alive because I took the sure way, not the technically legal way. As it worked out he turned right so we would have missed each other but I had no clue what he was going to do.

Ashling

1st Apr 2013, 00:08

Bubbers, clearly you missed the irony in my ho hum directed towards your earlier post when you mentioned airlines assumed you'd miss birds when they hired you. The ho hum was directed at the fact I got hired despite having hit birds previously. In fact it wasn't on the application form and they didn't even ask at interview, maybe it's different in the US of A

Your airprox makes no sense. You don't break right, which you should, presumably because you don't want to lose visual on the other aircraft, but then you roll inverted. All that does is keep you pointed the same way at the same altitude but upside down. More detail required. Can you even roll a Cessna 340 inverted in 2 seconds or less, I suspect not. Just as well the other pilot did what he should of.

By the way the professional thing to have done would have been to report it.

LSM, we're both forgetting he teach's aerobatics and cross controlled stalls so anythings possable

bubbers44

1st Apr 2013, 00:26

LSM, I missed thousands of turkey buzzards, not 7. They were in multiple flocks. We flew between the flocks, dodged individual birds and never hit one landing. They were easy to pick out, even the individual birds. You have to look out a long way to see them. I have missed thousands of birds by just looking out the windwhield in the valley. They are everywhere.

bubbers44

1st Apr 2013, 00:33

Report what? Obviously nothing happened so what is the point of reporting anything? It would go in the WTF file because there would be no documentation of the other aircraft so it would just die.

Ashling

1st Apr 2013, 00:53

You report airproxs in the USA? Is it mandatory to do so?

So far all you have done is roll inverted, that doesn't help you, your still pointing the same way. You need to add more info.

You say you had 2 seconds or even less yet you manage to roll a Cessna 340 inverted in that time and then roll with the conflict aircraft. That's a roll rate that would challenge most WW2 fighters.

I smell something

misd-agin

1st Apr 2013, 02:28

Hysterical.

Lord Spandex Masher

1st Apr 2013, 03:43

eyesight inverted is the same as upright. Try it sometime. We avoided a possible midair by just rolling over at the last second and it worked and yes, we could judge the distance from other aircraft with no problem. We had less than 2 seconds to respond so saved a possible midair collision.

Why not just push then? Save yourself the time it takes to roll 180 degrees. That way you could still see them through the windshield as it has greater extent upwards than downwards.

LSM, I missed thousands of turkey buzzards, not 7
I apologise, it's just that earlier you said
LSM, I have no idea how many birds I WOULD HAVE HIT. MY GUESS IS over 6.
Six you would have hit had you not avoided them plus the one you did hit would make seven no?

Anyway, let's go with your latest figure. You've dodged (ie. manoeuvred around), in a 757, thousands of turkeys that would have otherwise hit you? Does that question make sense?

If he had turned the same way we would have had a midair collision.
What would have happened if he thought you wouldn't do the right thing, which you didn't, and he'd rolled inverted...?

Ashling, it's a shame he's retired hey?! We need more pilots of his calibre to show us where we're going wrong.

JW411

1st Apr 2013, 07:31

I was always taught that when you find yourself in a hole, stop digging.

I would also like to know how you can see another aircraft through the floor of a Cessna 340.

Remarkable.

RetiredF4

1st Apr 2013, 07:58

To look out of the windshield will not help much, but to look/ search outside the windshield does the trick. You have to focus the eyes first to be able to pick up other stationary traffic or birds early enough. Otherwise you pick up the moving (moving in relation to the position on the windshield) stuff only, which is no threat anyway.

To focus the eyes look at a cloud, a contrail, a ground reference or other traffic already sighted some distance away for one second to focus it, then scan sector by sector. It is a procedure which has to be trained, as it is not a natural behaviour.

To push for bird avoidance is not helpful, as birds never will avoid traffic by going up. Especially big birds and flock of birds will fold their wings and dive.

Low level flying for 20 years (420-540 kts, 250-1500 feet AGL) offers lots of birds, gliders, hanggliders and small aircraft to practice visual lookout and evasive maneuvering.

@bubbers: It is law and well common practice in all countries i've flown that two aircraft on collission course turn away in the same direction, namely to the right. The aircraft with the higher position or in climb maintains this position, the other one levels off or descents.

Any other behaviour might be prone for desaster with manned traffic.

JW411

1st Apr 2013, 17:12

Actually, since we seem to have got heavily into birdstrikes, the most interesting one that I ever had was at 19,000 feet in the descent into Cologne at night (from Copenhagen).

We were between two layers of cloud so the ground was obscured and so were the stars which raises an interesting question - how was the bird navigating?

It was not a small bird and it made a hell of a thump but fortunately did not cause too much damage.

For the benefit of my Honduran Hero, I didn't see that one coming either.

Perhaps when I get a brain cell then I will be able to avoid such events.

NG_Kaptain

1st Apr 2013, 17:38

One incident that is not shown was the MD 83 taking off from Tobago which hit a flock of ducks. The ducks were migratory birds which decided to take up permanent residence in a lagoon right off the end of the runway, guess they got tired of going from Canada to Argentina every year and the sunny Caribbean seemed more attractive.
Was a night departures was impossible to see them. One engine ingested eight birds, the other five. The JT8 can handle five so was able to limp back and land in Tobago before it gave out, both engines were ruined. The captain is a poster here so maybe he can add some details which I may have forgotten.

CONF iture

2nd Apr 2013, 12:39

Never forget that the aircraft gave Sully the max performance it could even though it didn't get to Alpha Max.
It only means that the aircraft gave the maximum according to the way it was programmed - IOW there was no malfunction, nothing else.
To provide max performance would have been to let the pilot pull another 2 degrees on the nose even if the speed was already low, and by this to allow the pilot to reduce the vertical speed for the imminent touchdown.
Sully waited to be into the flare altitude before fully pulling on the stick, he did not do that in the approach or too early.

Don't blame the aircraft for a situation the pilot put it in.
To depict the normal functioning of the aircraft is not blaming it. The blame is on Airbus to not detail what is the normal functioning in the documentation provided to the pilot. The blame is on the BEA to not have detailed that normal functioning 25 years ago following Habsheim. The NTSB did what the BEA failed to do.

So depending on which vane you take or if you accept the pressure altitude value they had anywhere between 1 and 4 degrees spare to alpha max or 4 to 7 degrees spare to the stall.
The information the aircraft was working on was its own data as provided by the AoA probes, nothing else. Then the margin was 4 deg for alpha max or 7 for the stall. That's a lot when you only need 2 deg of attitude gain passing 50 feet for the flare to improve the touchdown.

Clandestino, in all modesty, mentioned (http://www.pprune.org/7765007-post146.html) that Sully had no business occupying any seat from which flight controls can be reached.
What's your take on this ?

Ashling

2nd Apr 2013, 13:56

Reading through the FCOM there's a Flight Crew Bulletin that refers to the calculation of protection speeds by FACs. Due to data accuracy, especially the accuracy of the AoA, the tolerance is 2.5% and during acceptance flights they work to a tolerance of 5kts.

So although you are correct when you say the aircraft worked to its AoA the gap to the stall may not have been as great as that AoA indicated which is what the pressure altitude and airspeed corrected figure appears to indicate. No doubt this is why there is a gap between Alpha Max and Alpha stall.

From memory Sully pulled full back at 50ft and held it. Due to his speed and longitudinal characteristics of the aircraft that input was attenuated. To me it's common sense that it will take a finite time to get to Alpha Max and also common sense that the input will be attenuated, that's what FBW does. This means you can pull full back and hold it at slow speed but not need to worry that you will stall. You don't snatch to the buffet at slow speed, its all gently does it if you want to avoid stalling. That said Airbus could provide more info than they do.

If he had been in a conventual aircraft 19kts below speed you would think/hope that the stall warning would be going off. Who's going to pull then?. In the Airbus he could and the aircraft gave him the best it could. He could pull as hard as he wanted and hold it, something he could not have done in a non FBW aircraft, he would not have outperformed the FBW.

Some will say that had Sully been in a Boeing he could have flown to the buffet. I don't buy that. 1. Because the stall warning would be going off and you are v bloody brave/suicidal if you pull then in an airliner 2. He had no training to do so in an airliner 3. He was under immense pressure and his flying had already suffered, witness his speed control.

CONF iture

3rd Apr 2013, 00:12

To me it's common sense that it will take a finite time to get to Alpha Max and also common sense that the input will be attenuated, that's what FBW does.
Looking at the elevator trace, there was simply no intention to go or get closer to alpha max.

He could pull as hard as he wanted and hold it, something he could not have done in a non FBW aircraft, he would not have outperformed the FBW.
I disagree on that. I think you put things as if the full back stick was taking place 200 feet or more - That is not the case - Sully needed the performance on the flare, not before.
Passing 50 feet at the present rate of descent, he was 3 to 4 seconds from impact. That was the perfect timing to go and get what was still in the aerodynamics to decrease the vertical speed. There was no sufficient time and more importantly no need to go to the stall.
To think the FBW would outperform the experience on a flare is not a call I would go for. The Hudson event indicates the opposite.

DozyWannabe

3rd Apr 2013, 00:24

What difference do you think it would have made to the outcome?

CONF iture

3rd Apr 2013, 00:52

The capacity to manage the flare and reduce the rate of descent for the Hudson and the possibility to survive from the branches in Habsheim.

Owain Glyndwr

3rd Apr 2013, 13:45

@ CONF iture

To provide max performance would have been to let the pilot pull another 2 degrees on the nose even if the speed was already low, and by this to allow the pilot to reduce the vertical speed for the imminent touchdown.

You have made similar statements several times, but unless I have missed something, you have never suggested how this might be done. Do you have any positive proposals for how the logic might be altered to achieve what you desire?

Ashling

3rd Apr 2013, 17:21

Confiture

Of course it would have been very nice for Sully to have got another couple of degrees but the aerodynamics meant the FBW denied him that. On that we both agree.

Why?

1. I've tried to put forward documented reasons. The accuracy of the AoA. While the aircraft measured a max of 14.5 below 150ft there is a margin for error so the real figure might have been higher, as the corrected figure suggests, putting them closer to the stall. The designer has to take this into account and the margin is equivelent to 5kts at Flap2 (FCOM) which is quite a-lot. They might of had a 6 degree margin but it may have been as little as 3/3.5

2. The energy in the aircraft. Any commercial airliner has a lag when responding to control inputs. That lag will be greater at slow speed. Obvious but true. As you say from 50ft in was 3-4 secs so not a great deal of time. They lacked the nose authority they would have had at the correct speed. Thats true in any aircraft.

3. Phugoid damping. Airbus refer to this as do the BEA as does the analysis on the aircrafts performance and they all give it as the reason why Sully's control input was attenuated. Now I'm not going to pretend I fully understand this, I'm not a TP or an expert on aerodynamics, but I do know that this refers to longnitudinal stability and I think in this case it is referring to a tendancy to pitch nose up close to the stall with large control inputs. In any case its the reason the input was attenuated so is key to the whole thing. Perhaps an Airbus TP can elaborate if anyone reading all this still has the will to live. You've never really addressed this point Confiture.

When I referred to pulling full back and holding it with impunity I was referring to the attempted flare at 50ft. I agree he had no intention to fly towards Alpha Max before then just as I think he had no intention of entering Alpha Prot. Thing is he did the later because his speed control was poor. When he pulled full back to flare he did of course intend to get closer to Alpha Max at that point.

I'm also very comfortable saying that FBW will outperform the pilot, me, any of us. Just the way it is.

In a conventialy controlled aircraft (for want of a better term) the stall warner would have been bleating away. Now what does the pilot do? What would you do, as again I feel you downplay this point. I wouldn't pull, not without considerable handling experience in that regime on that aircraft and as commercial pilots we simply don't get that. The absolute imperitive low down with no engines is DO NOT STALL. The Airbus took that concern away.

The aircraft protected him from a stall because he allowed his speed to decay too much. It did what it was designed to do. No speed decay no need for the aircraft to step in so to suggest a redesign is inappropriate in my view. The fault lay with the speed control not the jet.

Clearly this is my opinion and I do not pretend to have special insight or qualifications to judge. Others can take a view of the merits of the points we put forward. In the end I suspect we would need an Airbus TP to settle it or at least explain it.

Lonewolf_50

3rd Apr 2013, 20:46

Some of this discussion, though interesting, might fit better in the extended thread we had over Sully's adventure.

PPRuNe Towers

3rd Apr 2013, 23:29

Very diplomatic, very correct Lonewolf.

Rob

CONF iture

3rd Apr 2013, 23:34

If you pulled back on the control column of a 737 at 50' while 19 knots slow and sinking 700, as a minimum you would probably require some dental reconstruction work.
Certainly if you do it 200 ft in the air, but not from 50 ft.
As the aerodynamics for the 737 is probably not very different from the 320, the 737 20 kt below Vref with an AoA of 14 deg still requires a 20 deg AoA for stalling. Pulling on the control column will allow to get part of that margin to create lift and reduce vertical speed.
This must be reserved to a very transitory exercise known as the flare.

Again, not recommended at 200 ft RA.

sevenstrokeroll

4th Apr 2013, 00:44

hey, clandistino...thanks for that information you posted...I looked at it and NONE of the tail mounted planes had to land off airport...they landed in decent shape.

AS to Bubbers CHOICE not to answer spandexmasher...I agree with you bubbers, answering an ignorant annoyance at some point is just counterproductive. But don't feel bad spandex...you just won a crusie on Carnival cruiselines...make sure you take appropriate precautions.

and IF bubbers said he rolled inverted and avoided a collision, I believe him. Every fighter pilot I've known said, "no matter what, keep 'him'' insight and you maintain the advantage.

let me add another question to the sully debate...what if he had used some flaps?

CONF iture

4th Apr 2013, 01:20

You have made similar statements several times, but unless I have missed something, you have never suggested how this might be done. Do you have any positive proposals for how the logic might be altered to achieve what you desire?
I have no pretension or even desire here to modify the way the control law is programmed.
It can be a great idea to wish to protect an aircraft from stalling, but on that particular case on the Hudson, even if the speed was below Vref, it was still possible for Sully to reduce the vertical speed at touchdown and obtain the Airbus recommended attitude for ditching ... if only the elevators were to follow the pilot request.
Sully would have been better served with a direct law with full and known control on his elevators.

Lord Spandex Masher

4th Apr 2013, 01:36

AS to Bubbers CHOICE not to answer spandexmasher...I agree with you bubbers, answering an ignorant annoyance at some point is just counterproductive.

But then he did answer, and dug himself further into the hole by being counterproductive. :D

But don't feel bad spandex...you just won a crusie on Carnival cruiselines...make sure you take appropriate precautions.
I don't feel bad as I can distinguish between fantasy and reality. Crusie? Is that a mini sort of a cruise? Or an all in oner, like a onesie?

and IF bubbers said he rolled inverted and avoided a collision, I believe him. Every fighter pilot I've known said, "no matter what, keep 'him'' insight and you maintain the advantage.

Was he trying to shoot him down then? Every pilot I've known said keep a good lookout and then you don't have to do stupid things to avoid dying. Even so perhaps you can explain how you can keep someone in sight through the floor?!

Yes what if he had used flaps? Do tell, the suspense is killing me.

CONF iture

4th Apr 2013, 03:01

1. I've tried to put forward documented reasons. The accuracy of the AoA. While the aircraft measured a max of 14.5 below 150ft there is a margin for error so the real figure might have been higher, as the corrected figure suggests, putting them closer to the stall. The designer has to take this into account and the margin is equivelent to 5kts at Flap2 (FCOM) which is quite a-lot. They might of had a 6 degree margin but it may have been as little as 3/3.5
Again, the margin is already in alpha max, that's why alpha max has not been set to alpha stall by Airbus.
Also if there was any need to correct the figures it would be on a the safe side as both temp and altimeter were for more air density than standard.
The two recorded AoA data were in agreement around 13.5 deg some 4 deg short of alpha max.

2. The energy in the aircraft. Any commercial airliner has a lag when responding to control inputs. That lag will be greater at slow speed. Obvious but true. As you say from 50ft in was 3-4 secs so not a great deal of time. They lacked the nose authority they would have had at the correct speed. Thats true in any aircraft.
We could talk about a lag if the elevators had been following the pilot inputs ... but they did not.

3. Phugoid damping. Airbus refer to this as do the BEA as does the analysis on the aircrafts performance and they all give it as the reason why Sully's control input was attenuated. Now I'm not going to pretend I fully understand this, I'm not a TP or an expert on aerodynamics, but I do know that this refers to longnitudinal stability and I think in this case it is referring to a tendancy to pitch nose up close to the stall with large control inputs. In any case its the reason the input was attenuated so is key to the whole thing. Perhaps an Airbus TP can elaborate if anyone reading all this still has the will to live. You've never really addressed this point Confiture.
I can't pretend either to explain what phugoid damping exactly is. The way I see it is if the airplane is placed level in deceleration, idle thrust, and up to full back stick is applied, the airplane won't be able to quickly stabilize precisely at alpha max. Some oscillation may develop before eventually alpha set to alpha max.

I'm also very comfortable saying that FBW will outperform the pilot, me, any of us. Just the way it is.
It seems to be the case for a GPWS maneuver but is it for a flare ?

In a conventialy controlled aircraft (for want of a better term) the stall warner would have been bleating away. Now what does the pilot do? What would you do, as again I feel you downplay this point. I wouldn't pull, not without considerable handling experience in that regime on that aircraft and as commercial pilots we simply don't get that. The absolute imperitive low down with no engines is DO NOT STALL. The Airbus took that concern away.
If anytime during the approach he got a STALL warning, or an aural SPEED caution at CONF 2, it would have been an attention getter for Sully lo lower the nose and re established the speed at Vref or higher and get a better control on the flare later on.
The SPEED caution is inactive below 100 ft, I don' t know about the STALL warning, but you don't stall at STALL warning. In alternate or direct law the STALL warning is set around the level of alpha prot for normal law so the same margin is here again.
Normal law brings a physical but also mental disconnection between what a pilot does with the sidestick and how the elevators actually move. No such thing in direct law. Easier to understand.

Owain Glyndwr

4th Apr 2013, 06:46

@ CONF iture

Sully would have been better served with a direct law with full and known control on his elevators.

So is your recommendation that if you are going to ditch the pilot should switch (or be switched) to direct law?
If so, at what point should this be done?

BOAC

4th Apr 2013, 07:25

First time I have looked at this thread - and I had to go back and check it was about "American Airlines Flight 742"!

sevenstrokeroll

4th Apr 2013, 07:34

very glad you didn't have anything of great worth to say.

oh, and I posed the question about flaps, I didn't offer an answer.

I can imagine you and Spandex masher in the same cockpit...chatting away and forgetting to look outside.

yeah...so amusing.

"and still the villian pursued her"

Ashling

4th Apr 2013, 17:56

Confiture

Phugoid damping clearly applies in this case, Airbus said it did! We can agree that it causes oscillations, apparently on some types this can get divergent and possably beyond pilot control. I suspect its not that extreme on the Bus but clearly significant enough to protect against. Therefore the FBW prevents said oscillations by mitigating the pilots input or at least that's how I understand it.

Yes the margin is allowed for in Alpha Max which was 17.5 degrees. There was a split in the AoAs on the FDR, and the corrected figure was 16 odd degrees. It's in the performance study I posted a link to earlier. So taking that margin into account the gap between his actual real AoA and the stall may not have been as great as you have suggested.

When I said what would you do if you got a stall warning I was referring to a Boeing not an Airbus in normal law. If your in a Boeing (or a Bus in alternate/direct law) what are you going to do when the stall warning goes off at 150' because your too slow. Hard to push much and you'd be a fool to pull. Your in no mans land, no practise in that regime and no idea what your margin to the stall really is and in all probability no AoA gauge to tell you. The Bus took all that worry away, close to the stall FBW is ideal, carefree handling and all that, that's doubly true if you have no regular experience operating in that speed regime on type.

Putting the issue of the stall warning aside, in your Boeing even if you had room to pull and you did it at 50' you'd have 4 secs to impact. Given the relatively heavy weight, and slow speed I can't see 2 degrees making much difference, it would take a finite time to achieve those 2 degrees and a finite time for the aircraft to respond to that attitude change, it's a very different thing flaring at the correct speed to trying to do so 19kts slow, the aircraft won't respond the same way or anything close to it.

Anyway it's clear we're now pushing a few people's patience so perhaps it's time to accept, once again, that we differ. Hopefully if nothing else it will have made a few people think themissue's through for themselves and that can't be a bad thing.

ATB