Jump to content

Sign in to follow this  
Jacoba

AIR FRANCE 447: New details suggest the Airbus design contributed to the crash.

Recommended Posts

This is so true that many companies are replacing their Boeing fleet with Buses.

Then how do you explain the 451 orders for the 737 Max?

 

Did he write 'all'? :wink:

BTW, speaking of orders, A320 Neo has 1256 firm orders (plus 753 options).

 

As this is AF447 thread, I hope there will be no AvsB turn of the discussion.

Especially that some people are really crazy about A or B. See an extreme example of the A fanism:

 

Share this post


Link to post

Comparing AF447 to the Colgan crash is like comparing apples to oranges. The Colgan crash happened during approach when the aircraft was near 3,000' AGL. Nosing down at this altitude will invite the inevitable CFIT. There is nothing that crew could have done differently to recover from that stall. AF447 stalled at altitude. They had more time to correct. There is nothing wrong with the structural integrity of the A330. Discrepencies between pilot inputs caused the plane to operate outside of it's flight envelope, and break apart. Any plane would have crumbled under what stresses AF447 went through.

Share this post


Link to post

I agree that the two accidents are not really comparable, but it is probaably worth pointing out that a crash following a stall is not a controlled flight into terrain, by definition the aircraft is not controlled if it is stalled. And as far as I'm aware, AF447 did not break apart prior to impact.

 

I'd have slapped that woman on that video by the way for making that irritating wailing racket, what a complete fruitcake.

 

Al

Share this post


Link to post

I agree that the two accidents are not really comparable, but it is probaably worth pointing out that a crash following a stall is not a controlled flight into terrain, by definition the aircraft is not controlled if it is stalled. And as far as I'm aware, AF447 did not break apart prior to impact.

 

I'd have slapped that woman on that video by the way for making that irritating wailing racket, what a complete fruitcake.

 

Al

 

A stall wouldn't be a CFIT, that much is correct. BUT, pointing the yoke down and smacking the turf would be a CFIT. It's not the stall recovery methods that should be the object of debate by investigators, rather what led to the stall in the first place. There isn't much you can do to recover from a stall in a Dash-8 at 3,000' AGL besides enjoy the ride. I think both instances can be linked to inadequate training in icing conditions. The ASI would have been no good in either case being that the pitot tubes froze.

 

If AF447 didn't brake apart prior to impact, why is the integrity of the A330's fuselage even in question??? Hitting the water at a wrong angle is just as bad as concrete. If you put Sully in AF447, I don't think he would have done any better than the crew did.

Share this post


Link to post

There isn't much you can do to recover from a stall in a Dash-8 at 3,000' AGL besides enjoy the ride.

 

One thing to note is the aircraft wasn't stalled at first. The stall warning activated but it was an improper reaction and made the situation worse. Also stalling a Dash-8 is not like stalling a jet. It has quite a bit of power and nice straight high lift wings so a stall at 3000 AGL should easily be recoverable.

Share this post


Link to post

One thing to note is the aircraft wasn't stalled at first. The stall warning activated but it was an improper reaction and made the situation worse. Also stalling a Dash-8 is not like stalling a jet. It has quite a bit of power and nice straight high lift wings so a stall at 3000 AGL should easily be recoverable.

 

It was a tail stall. Not that easy to recover from when the elevators are iced up.

Share this post


Link to post

It was a tail stall. Not that easy to recover from when the elevators are iced up.

 

No. It was a stall caused by pilots with little experience, tired and could not recognize that they got to slow on approach. If it was a tail stall their 'technique' was appropriate and would have recovered.

Share this post


Link to post

It was a tail stall. Not that easy to recover from when the elevators are iced up.

 

The elevators weren't iced up and there's no suggest of that in the report.

 

The FDR shows the stall warning sounded correctly when the AoA reached 1-2 deg above the trigger and sounded continously for about 51 sec. During that period the FO took the AoA to more than 30 deg and the elevator to full nose-up position.

Share this post


Link to post

Then how do you explain the 451 orders for the 737 Max? :Nerd:

 

That's just one side of the question, how many orders have been placed for the equivalent NEO "buses"?

 

Don't get me wrong, i'm not PRO this or PRO that, it's just that people speak bad of Airbus as if they were a bad company, which is the exact opposite - They make good planes and give Boeing a serious headache... Anyway, this is offtopic and sorry i came out with this subject.

 

EDIT: That video.... HAHAHAHA! Crazy people!

Share this post


Link to post

 

 

It was a tail stall. Not that easy to recover from when the elevators are iced up.

 

Where are you getting this info from? The aircraft didn't break up and was fully controllable all the way down. The elevators where not iced up, the THS was full nose up due to the autotrim in alternate law.

 

AF447 didn't experience any severe stresses, dispite what some of the media reports suggest the passengers were likely completely unaware they were crashing

Share this post


Link to post

That was in reference to the Colgan crash, and not AT447. 2 discussions at once does get confusing.

Share this post


Link to post

Also, in terms of the Colgan crash, I'm more interested in what led to the stall instead of the recovery method. The PIC reconized the tail stall and fought the stick shaker. His action was correct, but it was too little too late.

Share this post


Link to post

The Colgan crash had nothing to do with icing or tailplane stall as the investigation has revealed, Marvin Renslow simply reacted to the noise and surprise of the stall and descent by pulling back on the stick and holding it there since pulling back on the stick is supposed to make the plane climb.

Share this post


Link to post

Again, I'm not interested in the recovery method. I'm interested in what led to the stall in the first place. A tail stall and air foil stall are different stalls that require different action. Stick pusher doesn't know the difference.

 

Fatigue and inadequate training was not the cause of the crash. They were a culprit.

Share this post


Link to post

Again, I'm not interested in the recovery method. I'm interested in what led to the stall in the first place. A tail stall and air foil stall are different stalls that require different action. Stick pusher doesn't know the difference.

 

Fatigue and inadequate training was not the cause of the crash. They were a culprit.

 

Stick pusher will not activate during a tail stall. The recovery method for a tail stall does not require realization of a tail stall. The actions for a tail stall recovery are the same as that of pulling out of a dive.

Share this post


Link to post

If AF447 didn't brake apart prior to impact, why is the integrity of the A330's fuselage even in question??? Hitting the water at a wrong angle is just as bad as concrete. If you put Sully in AF447, I don't think he would have done any better than the crew did.

 

The a/c did not break up during the descent. Hitting water at "any" angle at 124mph will smash the fuselage. Much of the receovered wreckage shows signs of massive compression forces caused by the impact. As regards Sully he may have identified the stall though more likely prevented the a/c from ever entering one in the first place.

 

AF447 didn't experience any severe stresses, dispite what some of the media reports suggest the passengers were likely completely unaware they were crashing

 

The a/c was falling at about 11,000fpm. Any fluctuations in the descent rate would most certainly have been felt by the passengers. It's quite likely that the cabin pressurisation system couldn't keep up with the descent rate so their ears would have been popping like mad. They would have sensed the extreme nose up position even in the dark. They would have heard the engines at full throttle. At the very least they knew they were in very serious trouble and quite possible more aware of the sittuation than the crew!!

vololiberista

Share this post


Link to post

Again, I'm not interested in the recovery method. I'm interested in what led to the stall in the first place. A tail stall and air foil stall are different stalls that require different action. Stick pusher doesn't know the difference.

 

Fatigue and inadequate training was not the cause of the crash. They were a culprit.

 

The Dash 8 has a reference speed switch that increases the speed when the stick shacker activates. They had this switch turned on at the time. The Stick Shacker went off at a higher rate of speed then normal. This was when the pilot reacted by pulling back on the yoke, followed by the co-pilot raising the flaps (further loss in lift) that resulted in the crash.

 

Section 2.2.1 in this article explain the reference speed switch:

http://www.alpa.org/...2-12_Colgan.pdf

Share this post


Link to post

It was a tail stall. Not that easy to recover from when the elevators are iced up.

 

That was in reference to the Colgan crash, and not AT447. 2 discussions at once does get confusing.

 

the NTSB's report states:"As a result, the NTSB concludes that the minimal aircraft performance degradation resulting from ice accumulation did not affect the flight crew’s ability to fly and control the airplane........The NTSB further concludes that no evidence indicated that the Q400 was susceptible to a tailplane stall."

 

Tthere was no tail stall and the elevators weren't frozen.

Share this post


Link to post

 

 

The a/c did not break up during the descent. Hitting water at "any" angle at 124mph will smash the fuselage. Much of the receovered wreckage shows signs of massive compression forces caused by the impact. As regards Sully he may have identified the stall though more likely prevented the a/c from ever entering one in the first place.

 

 

 

The a/c was falling at about 11,000fpm. Any fluctuations in the descent rate would most certainly have been felt by the passengers. It's quite likely that the cabin pressurisation system couldn't keep up with the descent rate so their ears would have been popping like mad. They would have sensed the extreme nose up position even in the dark. They would have heard the engines at full throttle. At the very least they knew they were in very serious trouble and quite possible more aware of the sittuation than the crew!!

vololiberista

 

I tend to ignore your rambling now however just to clarify a few things..

 

My comment was regarding reports such as 'terrifying dive of death' 'plunge of terror' etc etc

 

The human body only feels acceleration, once the aircraft was stable in the 10000fpm descent the ride would have been relatively calm with no excessive g-force, if anything it would feel like they were flying through a storm.

 

As I am sure you are aware climb thrust and TOGA are very close at high altitude, when the crew initially selected TOGA the initial increase in noise and N1 would have been minimal.

 

Point taken about cabin v/s, I am not saying the situation would not have been abnormal or frightening however I doubt many down the back realised they were dropping that fast and about to crash due to a lack of visual cues and minor sensory cues.

Share this post


Link to post

Firstly I take umbrage at being accused of "rambling."

Secondly in my mind I am pretty certain that the pax were in fact in fear of their lives. Even heavy turbulance causes many pax to freak out. Sadly for them they had an incompetent crew up front.

Thirdly with the a/c in the stall wind noise would have been much reduced so the engine noise would be more prevalent and similar to that heard on the ground and during take-off. That for any seasoned passenger would be very unusual. And I'm pretty certain they would have a. noticed that and b. noticed the initiation of the sink with the engines still going flat out. Again a seasoned traveller would be worried I'm sure.

We don't know for sure but if there was any light on the wings from the a/c somebody would have noticed, due to the enormous sink rate, the passing cloud going in the "wrong" direction!!"

vololiberista

Share this post


Link to post

Bickering over what the crew "felt" is irrelevant, as history has shown that most instrument pilots that focus on what they feel end up flying into something stationary. The crash was the result of the crews failure to recognize that they were dealing with degraded instruments and degraded fly-by-wire, reasonably basic instrument flight concepts. Had they realized this, and had they used more proper CRM they probably would have flown out of it.

Share this post


Link to post

Firstly I take umbrage at being accused of "rambling."

Secondly in my mind I am pretty certain that the pax were in fact in fear of their lives. Even heavy turbulance causes many pax to freak out. Sadly for them they had an incompetent crew up front.

Thirdly with the a/c in the stall wind noise would have been much reduced so the engine noise would be more prevalent and similar to that heard on the ground and during take-off. That for any seasoned passenger would be very unusual. And I'm pretty certain they would have a. noticed that and b. noticed the initiation of the sink with the engines still going flat out. Again a seasoned traveller would be worried I'm sure.

We don't know for sure but if there was any light on the wings from the a/c somebody would have noticed, due to the enormous sink rate, the passing cloud going in the "wrong" direction!!"

vololiberista

 

But as FLEX says unless that sink rate changes significantly then the passengers are going to feel will be limited to pressure and attitude and roll changes, which probably are going to feel like turbulence. I can't see how a seasoned traveller is going to tell that they're descending through cloud at a high rate whilst still moving forward as well if those in the cockpit are struggling massively with spatial disorientation. As you say we don't even know if any of the wing lighting was on and that would be the only way of telling which way the clouds were going (and we don't know how much cloud they passed through). Looking at the data the acceleration was at around 1g for most of the time, which is normal for severe turbulence yes? This is a genuine question.

 

To conclude simply that they were an 'incompetent crew' is a bit too easy, and does little for the development of safety. We have to try to (as I've mentioned in other posts) see what stimulus they were subjected to, how they reacted to them, and more importantly why they reacted that way to go forward from here. I believe that there are many factors that contributed to this crash which cumulatively caused confusion in the cockpit:

  • Spatial disorientation.
  • Distrust of the IAS, causing distrust in other instrument readings (very possibly the HSI) because of lack of other information such as being able to look out of the window and orient oneself.
  • Inconsistent stall warnings that were sounding when the nose was down and stopping when the nose was up.
  • Lack of training from AF for unreliable IAS recovery.

Along with a whole host of other things.

Share this post


Link to post

Stick pusher will not activate during a tail stall. The recovery method for a tail stall does not require realization of a tail stall. The actions for a tail stall recovery are the same as that of pulling out of a dive.

 

Stick pusher activates when the AoA is increased over the AoA that caused the stall alarm to activate. It does not know the difference between a tail and airfoil stall. The Dash-8 is not FBW. It is a conventional setup of pulleys and cables. And just a FYI, a stall (especially a tail stall) can happen at any speed.

Share this post


Link to post

Are you aware that in a tail stall, main wings are not stalled?

Share this post


Link to post

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  
×
×
  • Create New...