American Airlines Flight 742 "flight control system" problems

[Clandestino]

Wonder what you are going to make out of it but here it goes: N106US DFDR trace.

Originally Posted by CONFiture

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?

Originally Posted by CONFiture

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.

Originally Posted by CONFiture

Is it directed to Dozy

It might be refreshing change if we started concentrating on what is written, not who has written it.

Originally Posted by CONFiture

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

He is right.

Originally Posted by CONFiture

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.

Originally Posted by sevenstrokeroll

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.

Originally Posted by sevenstrokeroll

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.

Originally Posted by sevenstrokeroll

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

Question was simple, being evasive on it is not conductive to meaningful discussion.

Originally Posted by sevenstrokeroll

fly your airbus just as the computer says.

That would be in breach of operating manuals and, depending on outcome, might even constitute misdemeanor.

Originally Posted by sevenstrokeroll

Hal will take good care of you.

Wont, but that's what anyone reading and understanding FCOM knows.

Originally Posted by sevenstrokeroll

.a pilot must be able to fly the wings off a plane in order to save it

Saving the aeroplane through inducing inflight airframe failure. Needs no further comment.

Originally Posted by sevenstrokeroll

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.

Originally Posted by sevenstrokeroll

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]

http://www.exosphere3d.com/pubwww/pd...ket/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]

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]

Originally Posted by sevenstrokeroll

.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.

Originally Posted by sevenstrokeroll

.and if you fly the wings off the plane as your wheels touch the ground, you have lost your wings, but saved your passengers

For 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.

Originally Posted by sevenstrokeroll

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]

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]

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

[Ashling]

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

[bubbers44]

myopic means you can only see things close, right?

[bubbers44]

myoptic? Is that what you meant?

[bubbers44]

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]

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]

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

[sevenstrokeroll]

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]

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]

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]

Originally Posted by sevenstrokeroll

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

Originally Posted by sevenstrokeroll

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:

Originally Posted by misd-again

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.

Originally Posted by sevenstrokeroll

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.

Originally Posted by sevenstrokeroll

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.

Originally Posted by bubbers44

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.

Originally Posted by misd-again

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]

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]

Originally Posted by Clandestino

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]

Originally Posted by Capn Bloggs

It'll be the same one that provides collision-avoidance training when encountering an unknown VFR in Class E airspace

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



and this one:



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

Originally Posted by Capn Bloggs

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.

Originally Posted by john_smith

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.

Originally Posted by Ashling

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...

Originally Posted by Ashling

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.

Originally Posted by Ashling

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.

Originally Posted by Ashling

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]

Originally Posted by Clandestino

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?