Air France 447 - On topic only!

[ca787546]

Allow me to modify the scenario: You are in autothrust, THR CLB mode, cruising at .82M. N1 is around 90%. Entering turbulence, your speed target is commanded back to .80M. A/THR reduces N1 to around 70% to achieve the target speed. Then —BAM— ADR disagree. A/THR disconnects and thrust lock freezes N1 at 70%. A/P disconnects but auto pitch trim holds the level FPA, as the a/c continues to slow beneath .80M, by raising the pitch above your current 3°. This is not a static situation. There are two trends in effect. The speed is slowing and the pitch is increasing. If you do nothing what will happen?

Now what if you use the memory items? You get the thrust levers out of THR LK and back to CL. You plant the pitch at 5°. You have increased N1 from about 70% to about 95%. At FL350, how much thrust effect are you really going to get in pitch? How hard is it to very quickly correct that back to 5°? Now you are flying at a thrust/drag ratio that will neither stall nor overspeed for at least the time it will take to go to the QRH and set more exacting commands. I don't see how you can lose.

On the other hand, in opting for stasis (leaving things as they are), I see very clearly how you can get into a high AoA situation without touching a thing.

I agree, you have to do something. Analyzing this case, I would say I have control, and ask the FO to please read my turbulence penetration N1 for this weight and level from the QRH, it's in the blue tab I would say. That's what I remember straight forward from memory. If he was not quick enough to bring out the N1 number, I would then move the thrust levers to match the TLA on the E/W display, and analyze the situation. If the pitch seems to need to be increased to maintain the altitude, I would gently increase the thrust. If the pitch seems to be decreasing to maintain altitude, I would decrease the thrust gently. If the pitch remains more or less solid, I would leave the thrust where it is at. I would then say "I have control and communications, ECAM Actions please" if there are any ECAM procedures, otherwise I would ask for the Unreliable speed indication checklist from the ECAM. At this moment, the aircraft is levelled off for troubleshooting. I have flown that scenario in the sim Evan. I flew it with the exact same weight as the AF A330, I flew it at the same altitude, I flew it in moderate turbulence, and IMC conditions. And that was what we did. We did not stall the aircraft, we did not overspeed the aircraft. If you were to pull a little too much or increase the thrust too suddenly, you would likely get the "STALL STALL" warning, which would make me reduce the pitch by releasing some back pressure on the sidestick, or even put some forward pressure on the sidestick until the alarm stopped, and then try to get the aircraft back to level flight. I would also ask the FO to please put up the GPS page on his MCDU so I could have a back up of altitude to make sure that my altimeter indication hasn't become unreliable as well.
There's my answer.

[Fear_of_Flying]

I agree, you have to do something. Analyzing this case, I would say I have control, and ask the FO to please read my turbulence penetration N1 for this weight and level from the QRH, it's in the blue tab I would say. That's what I remember straight forward from memory. If he was not quick enough to bring out the N1 number, I would then move the thrust levers to match the TLA on the E/W display, and analyze the situation. If the pitch seems to need to be increased to maintain the altitude, I would gently increase the thrust. If the pitch seems to be decreasing to maintain altitude, I would decrease the thrust gently. If the pitch remains more or less solid, I would leave the thrust where it is at. I would then say "I have control and communications, ECAM Actions please" if there are any ECAM procedures, otherwise I would ask for the Unreliable speed indication checklist from the ECAM. At this moment, the aircraft is levelled off for troubleshooting. I have flown that scenario in the sim Evan. I flew it with the exact same weight as the AF A330, I flew it at the same altitude, I flew it in moderate turbulence, and IMC conditions. And that was what we did. We did not stall the aircraft, we did not overspeed the aircraft. If you were to pull a little too much or increase the thrust too suddenly, you would likely get the "STALL STALL" warning, which would make me reduce the pitch by releasing some back pressure on the sidestick, or even put some forward pressure on the sidestick until the alarm stopped, and then try to get the aircraft back to level flight. I would also ask the FO to please put up the GPS page on his MCDU so I could have a back up of altitude to make sure that my altimeter indication hasn't become unreliable as well.
There's my answer.

It sounds to me like the only memory item that really matters is remembering to fly the plane. A classic answer, ca787546. I really enjoy reading your posts.

[Theoddkiwi]

There's a more general issue here. I was thinking about past fatal incidents where pilots attempted inputs to planes' controls and the planes did the opposite. At least two 737 crashes and an MD80 crash in the Pacific by an Alaskan Airline plane. Does the data recorder record the input, or does it document both the input and the behavior of the component to which the input is directed. Because the article I read said the horizontal stabilizier was at 13 degrees, which it said would keep the nose up no matter what the pilots did. It raised the possibility that the system which accepts the input and directs the mechanism had a bug in it. Not only that,it says someone noted before the crash the same anomaly in a simulator.

Modern FDR's record both Control Column input and Flight control position independently from independent transducers.

The Usual setup for a control surface is to have two or three position transducers to measure the physical position of the surface. On of those transducers will be wholly dedicated to feeding data to the FDR and nothing else.
There will also be an independent dedicated transducer on the control column for the FDR.

Flight controls on fly-by-wire and and even regular Autopilot systems on an aircraft are closed loop systems. Which means when an input command comes from the control column or AP, the command goes to the actuator which then moves. Then the Position transducer sends back the control position. The Flight Control computer will look for a Null, which means the the flight control surface position has reached the commanded position. This a continuous loop of command reply command reply.

Basically the FDR would clearly show a mismatch between a pilot control command and a flight control position.

They would easily see of the aircrafts controls were not responding. The clearly have stated that the aircraft responded correctly to all Pilot Commands for the flight controls and engine controls.

The aircraft just did what it was commanded to do by the PF.

[EconomyClass]

This story doesn't encompass the final solution to the 737 rudder problem, but it does exemplify how airliner manufacturers can behave when crash issues are in doubt.

http://www.pulitzer.org/archives/5925

[Evan]

I agree, you have to do something. Analyzing this case, I would say I have control, and ask the FO to please read my turbulence penetration N1 for this weight and level from the QRH, it's in the blue tab I would say. That's what I remember straight forward from memory. If he was not quick enough to bring out the N1 number, I would then move the thrust levers to match the TLA on the E/W display, and analyze the situation. If the pitch seems to need to be increased to maintain the altitude, I would gently increase the thrust. If the pitch seems to be decreasing to maintain altitude, I would decrease the thrust gently. If the pitch remains more or less solid, I would leave the thrust where it is at. I would then say "I have control and communications, ECAM Actions please" if there are any ECAM procedures, otherwise I would ask for the Unreliable speed indication checklist from the ECAM. At this moment, the aircraft is levelled off for troubleshooting. I have flown that scenario in the sim Evan. I flew it with the exact same weight as the AF A330, I flew it at the same altitude, I flew it in moderate turbulence, and IMC conditions. And that was what we did. We did not stall the aircraft, we did not overspeed the aircraft. If you were to pull a little too much or increase the thrust too suddenly, you would likely get the "STALL STALL" warning, which would make me reduce the pitch by releasing some back pressure on the sidestick, or even put some forward pressure on the sidestick until the alarm stopped, and then try to get the aircraft back to level flight. I would also ask the FO to please put up the GPS page on his MCDU so I could have a back up of altitude to make sure that my altimeter indication hasn't become unreliable as well.
There's my answer.

Ok, thank you for that. I have no doubt that you are a well trained pilot with a very level head under extreme pressure and confusion. HOWEVER, there are Airbus pilots out there, probably quite a few, who would not react this way. It would not enter their minds at that moment that they were slowing for turbulence. It would escape their minds that the flight was not in a static state. Seeing themselves in stable 1G flight, they would do nothing to adjust (and stabilize) the flight path, but would go right to the ECAM and begin checklists. This seems to be what happened in those other reported incidents.

Now, lets say a lesser pilot than yourself is PIC, not as perfectly trained and subject to human factors, who in that chaotic moment does not consider the speed reduction issue or the ramifications of the THS and shares your conventional wisdom about maintaining control status. They can be in a stall before they realize the problem. They might become disoriented at stickshaker and botch the recovery as well.

Now, HOW DO YOU ENSURE AGAINST THIS? Because pilot quality is beyond their control, this is the question Airbus needs to address. By now they are well aware that the focused sequence you described above is unrealistic given the turbulent, confusing scenario and the variations in pilot quality. Therefore, we have every pilot follow a memory item procedure that will FIRST place the aircraft within a temporarily safe airspeed envelope. Unless you are at the limit of your flight envelope, where no climb gradient is available (and again, why the hell would you be there when traversing turbulent cloud formations where the UAS occurs?) there is no downside. So require everyone to do this and nobody gets hurt.

One of the key merits of a high-quality pilot is recognition of one's limitations and human weaknesses. Any high-quality pilot will see the value in having these memory items to safeguard against that one moment of forgetfulness or confusion that will cost them everything. I think few of the pilots who have experienced UAS at the top of RVSM were not humbled by it.

I also suspect that, when AF447 went down, most pilots were not getting the SIM time you are on this procedure, if any, and I hope that has drastically changed.

IMHO, Airbus needs to lose the "if the safety of the flight is in danger part" and replace it with "In the absence of terrain, APPLY MEMORY ITEMS:"

[Evan]

If the pitch seems to need to be increased to maintain the altitude, I would gently increase the thrust. If the pitch seems to be decreasing to maintain altitude, I would decrease the thrust gently. If the pitch remains more or less solid, I would leave the thrust where it is at.

This, BTW, is why I said earlier that I think the Airbus auto pitch trim can be very useful here. You can judge airspeed inputs by THS reaction. But after the memory items have been performed.

[Spectator]

Memory items

Here's a copy of the beginning of the Unreliable Airspeed Indication section of the current QRH (I'm now operating the A320 family aircraft, but I am certain it is similar to the information on the A330 QRH).

The first line of the QNR clearly states "...,and if below FL250". In other words the memory items that so many crews have been accused of ignoring were in fact not applicable?

Or is there a UNRELIABLE SPEED INDIC/ADR CHECK PROC - ABOVE FL250 procedure? Thanks for your input, ca787546.

[Gabriel]

The first line of the QNR clearly states "...,and if below FL250". In other words the memory items that so many crews have been accused of ignoring were in fact not applicable?

Very true!!!! I had missed it!!!

Not only that, but the title itself is (emphasis added):

UNRELIABLE SPEED INDIC/ADR CHECK PROC - BELOW FL250

And then the first line you mention:

Apply this procedure if unreliable speed indication, and if below FL250

So CA787546, please show us the procedure that applies ABOVE FL250. That is the relevant one for this accident.

[Evan]

So CA787546, please show us the procedure that applies ABOVE FL250. That is the relevant one for this accident.

The only one that is relevant to this accident is the one the AirFrance pilots had, the one in French. This is the one included in the interim report. It makes no mention of "Below FL250" and specifies only "Above FL100":

[Gabriel]

And it doesn't say "If the safe conduct of the flight is impacted".

Of course, PIC authority includes deviating from any regulation, clearance or procedure if he judges that following it is not safe (and that there is a safer course of action). But the difference is clear:

In one case you don't follow the memory items unless you judge that the safe conduct of the flight is impacted.

In the other case, you must follow the memory items, unless you judge that in this specific case it's not safe and that there is a safer thing to do. You may need to explain that deviation later, and you better have good grounds for your judgement.

For what we know so far, it looks that in this accident the FO just did what he did just. It doesn't seem to be any assessment of the situation and a decision not to follow the memory items because it was not safe and something else (like pulling up to 10º pitch and 7000 fpm without setting any thrust?) was safer.

[Evan]

From 2 h 10 min 05, the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row.

Very frustrating to not have the FDR to compare these vague statements. Why did this initial roll occur? Was it significant enough to result in overcontrol? Did he think this was a wing stall? Why would he pull the nose up before any indication of stall or UAS? To maintain FL in the bank? He is in IMC. His only attitude reference is the HSI. Upon A/P disconnect, did the slower airspeed combine with the added load factor of the roll to cause sink as well? I feel that something is missing here.

[Mikersey]

Simulator Training

Perhaps things have changed since I retired(off B767, B757,F100,BAe146, MD80,B727), but we were taught ONLY how to recover from an approach to a stall. I.E. Recover on stick shaker. We were never taught how to recover from an actual stall.
We were graded on no loss of altitude. In other words, we kept back pressure on the yoke, went max power, maintained altitude and accelerated out of the shaker.
An artificial situation for cetain.
I disagreed with the procedure -- knowing from military background, that relaxing back pressure on the stick, stopped the stall warning almost instantly.
Never, ever were we taught to lower the nose ... although that'd worked in many a case when airliners have augered in.
We were taught never stall. Period.
We were taught that recovery from an actual stall in a swept wing airliner would require 10,000 feet or more. Recovery from a deep stall?? Don't know of many cases right off hand when the crew successfully recovered from a deep stall. Many cases when they haven't.
Perhaps it's time to put an stall auto recovery into the software.
PS Procedure stayed the same when we were absorbed by a much larger airline. Can't speak for training at other airlines.

[ca787546]

The only one that is relevant to this accident is the one the AirFrance pilots had, the one in French. This is the one included in the interim report. It makes no mention of "Below FL250" and specifies only "Above FL100":

I have to agree with Evan on this point. The AF pilots had their manuals at their disposals. Obviously there have been a few corrections to the QRH, depending on the aircraft type and model (for example, I remember the aircraft equipped with BUSS has a much different UAS procedure.

[Jpmkam]

More bodies recovered.

Seventy-five additional bodies have been recovered from the wreckage of an Air France plane that crashed off the coast of Brazil two years ago, more than doubling the number of remains that have been found, the vice-president of the French victims' association told CNN Tuesday.

The remains have not yet been identified, Robert Soulas said.

Air France 447 plunged into the Atlantic Ocean on June 1, 2009, killing all 228 people aboard. The bulk of the wreckage was found this year after a search by robot submarines of an underwater mountain range.

Many bodies were still in the fuselage, investigators said at the time. Only about 50 bodies were recovered in the days following the crash.

Soulas got the news from a French government liaison appointed to deal with families of victims, he said.

"Personally, I would have preferred to leave the bodies of our loved ones on the seafloor," he added, repeating his long-held view.

The Brazilian national news agency Agencia Brasil reported Tuesday that Nelson Faria Marinho, head of the Brazilian victims organization, said that with the latest recovery, the number of bodies found since the accident now totals 127.

[Spectator]

The only one that is relevant to this accident is the one the AirFrance pilots had, the one in French

I agree 100%. The AirFrance manual is the only one applicable to discussions directly regarding this accident. But it is interesting to see other operators manuals while we discuss the general issue of how UAS is being handled at present.