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Air Asia Indonesia Lost Contact from Surabaya to Singapore

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Air Asia Indonesia Lost Contact from Surabaya to Singapore

Old 2nd Jan 2015, 19:09
  #1041 (permalink)  
 
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Firefly:

A/c can stall in any attitude and airspeed.
Nonsense.

We are talking commercial aviation here, not aerobatic puddle-jumpers. If you are pulling that much g that you stall with the nose low and with a high airspeed, then the stall-condition is NOT your primary problem.



Airphoto:

Anyone remember "step on sky"? Unload the plane to zero AOA and use rudder to level the wings
Yeah, except we don't use rudder to level the wings in commercial jets. The rudder is immensely powerful, especially with twins, and has to be treated with respect.

Let's say the left wing stalls and drops. If you kick too much right rudder, the swept wing makes the right wing violently drop. This leads to the perception that the right wing has now stalled, even though you may actually have successfully unstalled the aircraft. So you kick left, and now the left wing drops. And what you have just successfully achieved, is to do an American Airlines 587, and break your tail off. And it was all one big PIYaw and PIRoll (as opposed to a PIO), and nothing to do with the stall.

The recommended technique is push the c/c forwards (I term it this way for a reason), reduce the thrust a bit, gain some speed, and THEN roll the wings level. Simple and safe.

Last edited by silverstrata; 2nd Jan 2015 at 19:25. Reason: new section
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Old 2nd Jan 2015, 19:12
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...and that's exactly what may have happened this this accident.

Nonsense?
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Old 2nd Jan 2015, 19:28
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The nominal G limit choosen for the high operation coffin corner is 1.3G. Flying a 30 degree bank angle will stall you there. What about any updraft in an ITCZ CB?
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Old 2nd Jan 2015, 19:47
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silverstrata, it may be nonsense to you but it's fundamental that an aircraft can stall in any attitude and airspeed.
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Old 2nd Jan 2015, 20:02
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Lurking slf comment alert!

What always surprises me reading these threads is the amount of disagreement among the pro's about topics which I would have thought were quite basic such as stall recovery. I hope as a fare paying passenger that this is because many comments are from people who are not actually professional pilots.

I strongly suspect that in a year or two's time when the report into this has been finalised, it will be shown to have been something nobody's yet thought of.

Thanks for the opportunity to comment.
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Old 2nd Jan 2015, 20:20
  #1046 (permalink)  
 
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I must agree with Silverstrata. Even in light aircraft we do not teach using the rudder to lift a wing. Its apply sufficinet rudder to stop the yaw, and ease the control centrally forward to reduce AoA and increase airspeed. Increase throttle to reduce rate of sink, but be aware that increased power may tend to raise the nose. Once airspeed has been regained then its aerilon to roll level, and ease control back to obtain correct attitude.

Using rudder to lift a wing will often cause unintended secondary effects.
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Old 2nd Jan 2015, 21:00
  #1047 (permalink)  
 
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Anyone remember "step on sky"? Unload the plane to zero AOA and use rudder to level the wings
Works great on some airplanes, AA over Long Island not so much
Yeah, except we don't use rudder to level the wings in commercial jets. The rudder is immensely powerful, especially with twins, and has to be treated with respect.
Well, actually years ago American Airlines had an Advanced Aircraft Maneuvering Program that taught aggressive use of the rudder to level the wings in an upset recovery. This AAMP was all the rage in airline training departments and in my opinion rudder use was sometimes implemented to an extreme degree in recovery profiles.

As the FAA put it in the 'Lessons Learned' from the AA 587 crash:

8. The American Airlines Advanced Aircraft Maneuvering Program ground school training encouraged pilots to use rudder to assist with roll control during recovery from upsets, including wake turbulence.

9. The American Airlines Advanced Aircraft Maneuvering Program excessive bank angle simulator exercise could have caused the first officer to have an unrealistic and exaggerated view of the effects of wake turbulence; erroneously associate wake turbulence encounters with the need for aggressive roll upset recovery techniques; and develop control strategies that would produce a much different, and potentially surprising and confusing, response if performed during flight.
From: lessonslearned.faa.gov

AA Captain Warren VanderBurgh, famous for his 'Children of the Magenta Line' speech, is also closely associated with the AAMP.

These days, rudder kicks in airliners to recover from an upset are definitely no longer in the vogue I would say.
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Old 2nd Jan 2015, 21:04
  #1048 (permalink)  
 
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These days, rudder kicks in airliners to recover from an upset are definitely no longer in the vogue I would say.
As far as I was concerned it never was.
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Old 2nd Jan 2015, 21:55
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SLF question about AoA and pitch attitude

Hello, I hope this isn't too much of a tangent.

I follow these threads mostly to help deal with my SLF flying anxiety, and it really does help. Apologies in advance for sloppy terminology or other ignorance. My O Level physics was a long time ago.

Can anyone clarify something about aircraft stalls for me?

The Wikipedia page on aircraft upset, allegedly quoting an FAA manual, suggests that "pitch attitude" is one critical factor in stall conditions. This has confused me because, following this and other similar threads here, I thought the critical factor was not pitch (which I understand as the lengthwise inclination of the aircraft relative to the horizontal plane) but angle of attack (which I understand as, roughly speaking, the angle of the wing to the airflow).

Thanks to anyone with the mercy and patience to respond.
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Old 2nd Jan 2015, 22:05
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.. it probably comes from very high aspect ratio sailplanes, as well as some military aircraft (built like brick ****houses)

In the sailplane case, aileron would do very little or even a control reversal and pilot wouldn't want to push forward much (increase sink, or fall out of thermal) and a wee (but rapidly applied) bit of rudder keep that wing from dropping further (being a massive span).

Also note that it isn't always the 'dropping' wing that is the problem but the 'dragging back' wing, due to stall drag. With slower larger span aircraft the difference between outer and inner wingspeed is not insignificant... and may need correcting rapidly.. hence rudder!

How AA were conducting that programme without Airbus' input or comment and why, when an aircraft has most all the inbuilt stability to deal with most things thrown at it... well?

Controls centred and see what happens, then correct alittle (and consistently) if it climbs, dives or rolls away... (in heavy turbulence) could perhaps be one way of summing up a general approach.
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Old 2nd Jan 2015, 22:47
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@HarryMann:

it probably comes from very high aspect ratio sailplanes, as well as some military aircraft (built like brick ****houses)
As well as from vintage taildraggers, like Cubs and Champs, which didn't feature things like differential ailerons -- they probably hadn't been invented when these aircraft were designed -- and with which margins for error are greater.

@Eutychus:

I thought the critical factor was not pitch (which I understand as the lengthwise inclination of the aircraft relative to the horizontal plane) but angle of attack (which I understand as, roughly speaking, the angle of the wing to the airflow).
Your understanding is basically correct. The Wikipedia article is imprecise.

Most of the time (e.g., calm air and unaccelerated (1G) flight), the airplane's pitch attitude and its wing's AoA are coincident -- tied to each other. (Which is not to say the airplane's pitch attitude and AoA are the same.) It gets more interesting when gusts with vertical components, G-loading and other factors are considered.

It's rather common for the wing's critical (stalling) AoA to be exceeded even though the airplane's pitch attitude is not as high.
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Old 2nd Jan 2015, 23:09
  #1052 (permalink)  
 
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Professional has little to do with it, it is more what they fly. My experience is all in straight wing piston and turboprop airplanes. Swept wing jets can react a *lot* differently than small straight wing airplanes.
That said, there ARE different schools of thought about how to fly all kinds of airplanes. That makes all these forums and pilot break rooms entertaining The flight school I went to was one of the "new way to fly, don't scare the students, we love our utterly benign nice wing wash-out Piper Warrior" schools. Coordinated rudder and aileron recoveries were what we learned and the planes tolerated it. Later on I learned from old time fighter pilots in some less forgiving airplanes the real use for rudder pedals
If I ever get type-rated in a jet the stall recoveries will be taught specific to that airplane. As of yet no one knows if stalls had ANYTHING to do with the current crash.

@Midland63
What always surprises me reading these threads is the amount of disagreement among the pro's about topics which I would have thought were quite basic such as stall recovery. I hope as a fare paying passenger that this is because many comments are from people who are not actually professional pilots.
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Old 2nd Jan 2015, 23:48
  #1053 (permalink)  
 
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you cant assume the a/c stalled

some years ago a Miami based commuter (CRJ??) flew through CB over Freeport, Bahama. The crew lacked cold weather operations and neglected to turn on the a/c heats. According to reports the a/c tail accumulated substantial amount of ice resulting in the a/c tumbling tail over nose several times. The crew was able to regain control of the a/c only to have the a/c tumble once again tail over nose several times. The crew regained control and landed safely. What did ATC observe on their screen that day?

Was the Airasia pressure vessel compromised at high altitude? if so could the crew don their mask? other factors -30/-40 degree temps, spin, inverted spin, inverted a/c etc
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Old 3rd Jan 2015, 00:11
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Also, the bodies recovered by the US ship today were reported to be more than 30 miles (confirmed was not kilometres) (source BBC news) away from the other bodies, and some were still strapped to their seats. That seems to suggest a possible mid-air breakup.
While not ruling out the possibility of a mid-air breakup, this discovery would not necessarily provide evidence to support it. In the normal ocean currents over 5-6 days this distance is perfectly plausible for drift in the water.


This is courtesy of NASA and shows the currents for December 2013. 0.5 m/second = approx. 1 nautical mile per hour. While an object will not travel at the same speed as the current, over 96 hours since the crash, 30 miles is possible if the aircraft broke up on impact.

Last edited by freespeed2; 3rd Jan 2015 at 00:30.
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Old 3rd Jan 2015, 02:16
  #1055 (permalink)  
 
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Design

For the moment we don't know what happened.

1. But why did the information of the very crazy vertical speeds, aswell climbing and descending, seen on the radar scope, need so many days to be published?

Some individual seem to have been quickly informed : to build a storry?

2. Is it the core of the crash of the Air Asia A320? But once again we have the discussion about the zoom climb followed by a decreased lift -stall or drop- possibly due to the "system".

I will say it again and again, any system, FBW or classical- needs absolutely two qualities : OBSERVABILITY and CONTROLLABILITY :

In the classical -and simple, because we don't need complexity to fly!- aircrafts, without these limitations called "protections", the pilot uses his/her stick to control the effective system, for instance to avoid overspeed.

But in a FBW system the pilot is "limited" in his/her action in that controllability.

In consequence we need another actuator to control the aircraft after that limit is reached. In the gums' F-16 exists a Nz actuator on the top of the stick controlling Nz and gums may control his aircraft. But in Airbus airliners no such actuator exists... Controllabilty is lost...

My question is : who decides during the design which actuators will be present to do what? Aeronautic Engineer or System Engineer? I think the latter who did not order the actuator to the first
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Old 3rd Jan 2015, 02:25
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Well,all this talk is well and good but no one has the guts to say what is obvious.Airmanship is not taught and nurtured anymore,especially in Asia/Africa.Was it ever I hear you ask.Cant say third world anymore as its verboten.They only teach SOP's and rote automated flight.Even the supposed legacy carriers in the region like Jet Airways.I witnessed the CP of Adamair(same airline where this Air Asia pilot previously worked) land at Pontianak with flaps 15 and a touchdown speed of 175 knots.Ive seen it all and its a long list of woe believe me including:
-wx radar brightness at min during day so no returns showing
-attempting to traverse storm cells with range set to 80 leading to blind alley
-afraid to disengage AP unless below 500
-flying manually(those brave enough to try) with AT engaged and unable to maintain alt in a turn
-No idea of N1 and pitch for different flight regimes
-unwilling and unable to fly a standard visual approach
-following magenta line into storm cells(that was Air India Express at Calicut)
-blocking out all the flight deck windows with the Jakarta Times
-totally lost without flight director
-plethora of hot and high approaches(AP engaged with GS capture,speed building and cant take flap)-classic case and very frequent due military airspace and late descent clearance-dont understand concept of energy management when forced to maintain altitude
-focus on complex unnecessary SOP(look at Lionairs lights policy for example-Its a landing light for Gods sake,put it on when youre landing and no it doesnt matter who puts it on) all the while neglecting to instill basic flight skills in their pilots.
-not being able to work out descent profile but blindly following VNAV even if its not appropiate to reality
-cant fly in HSI mode,only MAP..whats a VOR?NDB?Raw data anyone?No,just give me that good old magenta line.
-putting FO's on line who cant takeoff/land and its approved by their CAA even without a third pilot
-Pilots with 5000+ hours who have never not used autobrake
-hard landings
-bounced landings
-FDM used incorrectly as a means of intimidation so basic flight skills(manual flight ILS/visual approach) cant be practiced on line

The list goes on.I should write a book.How I escaped flying in the Far East and lived to tell the tale.
The way I see it is we need to call a worldwide conference and look at what automation,SOP/rote focus and P2F has done to our profession.Let the airlines who still know a thing or two about real flying(airmanship) like Qantas/SWA/BA/Lufty take the lead and see what we can do to stamp out this menace that is giving our profession a bad name.Because if we dont do something about it and planes keep crashing because there was no glidelsope or because they pulled rather than pushed in a stall we may just find ourselves redundant.Right now a pilotless airliner is bad joke but who knows in 20 years?
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Old 3rd Jan 2015, 03:03
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Yes, a return to western imperialism is definitely called for.
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Old 3rd Jan 2015, 03:26
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You would think that the guy would get seat of the pants flying credit for his F-5 time. They are about as automated as a Volkswagen beetle.

And all his flying time was on or near the ITCZ so he couldn't have been a neophyte where it comes to weather.

I have had no hesitation pointing a finger at Zaharie, but this guy had all the makings of a good pilot AFIK.
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Old 3rd Jan 2015, 03:39
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Bud leon, this has nothing to do with imperialism.

This is a hard reality. Flying in Asia for many years now, I cannot disagree with caulfield views and observations. Of course it may or may not be relevant to Air Asia's current misfortune.

I fly with first officers who are ready to upgrade to captain, and have NEVER flown the A320 without ATHR. NEVER flown with FD's OFF. NEVER opened a book about aviation since they got their CPL, except the simulator syllabus for a 6 month check. Only when fully established on the ILS will SOME disconnect the autopilot before the minimums or 500 feet.

When you ask some basic questions like how TAS can be estimated, the answer is "look at FMS distance remaining and divide by the flight time to destination". No joke.

The laws of physics and aerodynamics are not to change, but over the years, beancounters et al. have sold to a wide audience that with today's technologically advanced aircraft, all you need at the pointy end is a couple of guys pushing buttons to keep all flight parameters in check. Nothing could be more wrong. This includes how the wx radar is used. This includes, unfortunately, how decision making is integrated, or not, in today's airline culture.

I do hope the above-mentioned aspects will not be found to be a contributing factor in the demise of this aircraft. But it is a possibility.
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Old 3rd Jan 2015, 03:41
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Ive seen it all and its a long list of woe believe me including:
Thanks for sharing this list. I've seen much of that in my expat days, the folks back in the U.S. think you are making stuff up if you tell them about it.

Unfortunately, I'm starting to see some of the same trends in the U.S. lately.

To add to the weather discussion, this article from the Malaysian Star tabloid:

Updated: Saturday January 3, 2015 MYT 11:10:53 AM

AirAsia QZ8501: Ice likely culprit in crash

SINGAPORE: Extreme bad weather triggered last Sunday's crash of AirAsia Flight QZ8501, Indonesia's weather officials said Friday, as Russia became the latest nation to get involved in the search effort for the doomed jetliner.

The 14-page "meteorological analysis" is the first official word from Jakarta on the reasons for the crash and comes close to confirming widespread speculation on the reasons for the disaster.

"The most probable weather phenomenon is that icing caused the plane engines to be damaged," said the report by Indonesia's Meteorology, Climatology and Geophysics Agency (BMKG).

"This is however just one analysis of what likely happened based on available meteorological data, and is not the final determination on the cause of the incident."

BMKG's report, authored by Professor Edvin Aldrian, head of its research and development unit, came as high waves impeded divers from entering the sea.

...BMKG said its preliminary analysis of weather data suggested the AirAsia Airbus A320-200 had flown into storm clouds. It also noted that weather charts issued before the flight showed the plane's scheduled route at cruising level would come across "worrying" conditions, with warnings of a gale. Satellite images also suggested peak temperatures of -80 to -85 deg C, which meant there were grains of ice in the dense clouds, the report added.
AirAsia QZ8501: Ice likely culprit in crash - Nation | The Star Online

The BMKG report, written in Indonesian, is here:

http://data.bmkg.go.id/share/Gambar_...TEOROLOGIS.pdf
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