Air France 447 - On topic only!

[Gabriel]

I'm certainly not an expert here, but from the research I've done it would appear to be quite tricky to get this exactly right. Simply lowering the nose would increase airspeed and hence the chance of an overspeed. Retarding throttle on the other hand decreases airspeed and hence the chance of a stall. I believe a I read somewhere that they basically had a 6kt "sweetspot" that they had to remain within! While the computers were talking to each other and working properly the automation was able to maintain this, but when the fan became soiled they had to go manual. It's my understanding that this is why the SOP dictates power 85% and a prescribed attitude will hold things as straight and level as possible while the crew can run down what's going on.

As I said, I'm not an expert, but if my understanding of this is wrong I'd welcome an explanation from one who is.

I agree. In such a situation I guess you want to KISS. If you are already at cruise, the trying to keep it at cruise in the ballpark of the state that the plane was flying before the airspeed indication failure would make things much more smooth, stable, and easy than doing big changes of attitudes and thrust. In the ideal case (remove automation here), the plane doesn't care what the airspeed indicator is showing. If you are flying at one speed and one constant altitude, and are using one thrust and one pitch to do that, then as long as you keep the thrust and pitch the plane will keep flying at the same speed and altitude regardless of if the airspeed indicator needle starts to dance around the quadrant.

[guamainiac]

Probably not a factor in this incident .. but there had been a few accidents attributed to excursions into that zone in Lear and a few Boeings.

Some folks would extend the flaps a tick in cruise and I believe the Lear pilots would pull the breaker on the stick shaker.

[Evan]

Why?

Because I don't think it's possible to reach Mmo with CLB or even MCT power at FL35 if you maintain a pitch of 3-5°. I think the air is too thin at that altitude for that level of thrust to have enough real effect to overcome the drag. I think the only real danger of overspeed is from the pilots letting the pitch fall below that attitude. But, holding that same pitch, if the power is reduced to, say 70% N1, I would expect the plane to lose altitude, as I think it requires something in the neighborhood of 83-95 N1 to maintain altitude at that pitch. Now, what is turbulence penetration N1 for this scenario? This could have been the setting when the A/THR failed and went into thrust lock, and it might have been less than what is needed to hold altitude.

[Theoddkiwi]

Well, the Do228 between Röst and Norwegian mainland had a complete blackout due to lightning but landed safely anyway.
I personally dont rule out terrorism but its highly unlikely.

I never said lightening cannot damage or degrade an aircrafts systems, just that it is very very rare an in my experience as an avionics LAME. I have only seen one aircraft, in my ten years of working on commercial aircraft who get struck every other week, suffer reasonably serious issues where the crew had to take some actions.

Damage is cause by the current meeting resistance which then heats up the area and it burns or melts.
Perhaps there is merit to the idea that a larger aircraft will be less susceptible to damage due to its greater surface area of metal airframe allowing a lower resistance to flow through than and smaller one such as a Do228

I could also argue (without knowing any facts at all) that with the Do228 example, if incorrect maintenance/inspections had been carried out and bonding was insufficient or non-existent between components then the chances of damage will have increased. Not that it was struck by lightning but rather that its design was compromised.

On one or aircraft types missing or broken bonding straps can ground the aircraft on the spot or have a small repair window of a few days. Bonding is very critical to the the integrity of the aircraft with regard to lightening.

Perhaps i need to clarify myself further then.
I believe that lightening did not cause 447s crash but there is a chance that perhaps poor maintenance due to bad component bonding may have contributed to system problems had it been hit by lightening.

[Black Ram]

BEA Update for May 9th:

"The French Navy patrol boat La Capricieuse reached the search vessel the Ile de Sein on Saturday 7 May during the morning. It is currently sailing towards the port of Cayenne with the flight recorders, under judicial seal, on board. Also on board are the Investigator-in-Charge, an investigator from CENIPA, the Brazilian equivalent of the BEA, and an Officer of the French judicial police.

The patrol ship should reach Cayenne by the morning of Wednesday 11 May. The flight recorders will then be transported to the BEA by plane.

Recovery of airplane parts has continued over the past few days, with one engine and the avionics bay, containing onboard computers, having been raised."

Some new pictures:

http://www.bea.aero/fr/enquetes/vol.af.447/info09mai2011.en.php

[Theoddkiwi]

Just did a search for the D0228 incident and found the report. Assuming it is the same one.

http://www.aibn.no/aviation/reports/2007-23-eng?ref=1713

Kato Airlines KAT 603, flying between Rost and Bodo was hit by lightning striking the nose and traveled down to the tail. Its burnt out a number of the bonding straps between the fuselage and the tail. Energy also passed though the elevator rod and damaged the rodend resulting in a breach of the elevator control rod.
Electric pitch trim had to be used to maintain control, but all remaining systems remained intact.

They landed heavily on the second attempt and the crash landed but all survived.

In the report it was found that the tails bonding was degraded and perhaps some of the straps were broken before the strike, and others were old and worn. The degraded bonding likely increase the current passing though the control rod leading to its failure.
The NCAA issued and AD requiring all of the aircrafts type to have their bonding jumpers inspected, but strangely the AD does not ask for routine or subsequent inspections.

Not sure what school they went to but Bonding should be regularly inspected and checked.

[Theoddkiwi]

BEA Update for May 9th:
Some new pictures:

http://www.bea.aero/fr/enquetes/vol....mai2011.en.php

Thats incredible how good a condition everything is in after so long under the sea. The engine looks spotless. Just amazing.

Its looks to me like they are going to try to bring everything up.

[Joe H]

While much of what you say is true Joe, don't forget the fact that the old school style of aviating had more than its fair share of problems, and there are many accidents directly attributable to the styles of some of these guys.

Those "true airmen" you describe, while many of them were and are excellent aviators, were not all without fault. Accident rates have decreased, not increased, in the modern days of the 'zero to hero' pilot. What has changed is the cause of the accident.

Airbus themselves have acknowledged that the pilot has been left out of the system too much, however there seems a real reluctance by the industry to take any positive steps towards putting more manual control back in the pilot's hands. Its a catch 22.

You want your pilot to be current and well practiced at hand manipulation of the aircraft for the emergency situation, however he is often prevented from flying the aircraft in even good conditions as statistically it is safer with the automatic systems engaged.

I do still laugh at the reasons for removing the pilot from the cockpit, and the false economy around it. Many of the accidents we see are occuring DESPITE the best efforts of manufacturers to make their aircraft foolproof. Its time people got their head out of the sand, stopped wishing for the pilotless aircraft, and started putting some effort into ensuring the pilot-aircraft interface is optimised to improve safety.

We will be far safer when we actually take that step back from total automation to put the human right where he belongs... at the centre of the loop. Give the required training, and ensure the information he needs is provided in the best way possible for human interpretation and awareness.

At the end of the day, however, the public gets what it asks for. The public demand dirt cheap fares, and so corners need to be cut. At the moment it is wages of staff - that seems to be the way to cut costs. Of course, its all based on the concept of affordable safety, and the odd aircraft loss here and there is more than acceptable to many parts of the industry as it is still the cheaper option.

Hi MCM, many thanks for your response.
I am not sure about the 'step back' - but agree generally with you. I think we either have a system that allows (and absolutely no disrespect Evan !) the guarded switch to go full manual, - but, that is not really possible as there are no real manual backups like Aloha etc... - or, we build the response into the system....
Ok, fair point would be, so what if the 'systems' fail ? .. well, the answer is on the lines of, WHEN it fails, what can the pilot (human) actually DO ?. often the answer is NADA, because we have built OUT, not IN, that ability.
As you rightly say, is is definitely a catch 22, we have one, or the other, the grey area is the bit that causes the issue. and will long remain controversial. IF we have a HUMAN, then he or she MUST have at some point in a failure cycle FULL authority, if not, then we are reliant on the technology.. again Catch 22 !!!!.. without that, why do we have the HUMAN ? , if he cannot HAVE the Authority... back to square one..

It IS a really difficult issue, and concept, we are removing the ability for full authority.. as this happens, we cannot rely on human input.. or, we allow full manual fallback, again, I do not thing beyond a 732 there is much chance of that, and that was limited but did the job on the odd occasion.

I would be interested in your view as to where we draw the line ?


-
Re, I think it was Gabriel, the Colgan, yes you are correct, and I stand by what I say, I think He THOUGHT he was in a tail stall, I also do not for more than one minute think he took appropriate action.. but that is an aside, appropriate reaction would surely have led him to believe it was NOT what he thought therefore treat it differently.

It is a veritable minefield.

Thankyou for all the valued input.

Joe.

[Evan]

Hi MCM, many thanks for your response.
I am not sure about the 'step back' - but agree generally with you. I think we either have a system that allows (and absolutely no disrespect Evan !) the guarded switch to go full manual, - but, that is not really possible as there are no real manual backups like Aloha etc... - or, we build the response into the system....
Ok, fair point would be, so what if the 'systems' fail ? .. well, the answer is on the lines of, WHEN it fails, what can the pilot (human) actually DO ?. often the answer is NADA, because we have built OUT, not IN, that ability.

Joe, that's not true at all. I think there's confusion of the issue at hand. There are two aspects being discussed here, computer flight protections and fly-by-wire. Fly-by-wire is the future, unequivocally, but it only represents the interface between the pilot (autopilot or human) and the control surfaces. In both Boeing and Airbus FBW designs, the human pilot can have full authority, but in both cases the computer will interpret the intentions of the pilot to the actual control surface movements.

Think of this in three tiers. Tier one, The FBW interface, like every aspect of modern aircraft design, is built to be failsafe as opposed to being able to survive total failure. The A330 has five fully redundant flight control computers, meaning any single one can perform the FBW aspects of manual flight (The mechanical back-up is really not designed to provide precision flight control needed for landings, but only temporary flight control while systems are restored). What are the odds of all five of them failing? Probably much lower than mechanical control cable failure.

Tier two is the fault-detections and comparative function of the systems, the way in which redundant systems cross-check and compare one another to assure that there is agreement between them and no signs of anomaly. This is the area that has failed in the past, both on Boeing and AIrbus aircraft (this point-of-failure exists on non-FBW aircraft as well: it was a major contributor to the Turkish 1951 crash). It sent a Malaysia AIrlines 777 temporarily out of control. It sent a Quantas A330 into an uncommanded dive. All of these 'software glitches' have apparently been removed, but it shows the reason why we need a human pilot to have authority. In both Boeing and Airbus aircraft, the pilot has that authority to override these systems, but only Boeing provides an intuitive means for doing so. The AIrbus philosophy is to trust the aircraft more than the pilot.

Tier three is the flight envelope protections. Both Boeing and Airbus FBW aircraft have these, but again, Boeing allows them to be overridden intuitively through breakout force while AIrbus ADIRU systems have to be shut down to degrade control law before they are removed.

Now which is the better philosophy? You have to look at the causes of these incidents. Malaysia 124 was the result of bad maintenance procedure and bad pilot training. During the event, the crew disengaged the A/THR but left it armed, so it kept trying to reengage, perpetuating the problem. So pilot error was a key factor. Turkish 1951 was also pilot error. The crew should have been watching the airspeed, A/THR mode and the PF should have had one hand on the thrust levers. Qantas 71 and 72 were preventable. In both cases, the fault detection worked. There were indications of ADIRU issues before the events, and the pilots did not have the right procedures to deenergize the units. At the time, this was due to AIrbus not providing the proper procedure, but if it were to reoccur, it would be due to pilot error.

So, in all of these instances, human error was at fault. In all of these cases, provision existed for the pilots to take control of the situation. FBW itself is perfectly safe. The systems are designed with enough redundancy to be safe, but human error continues to be at the heart of the problem.

Now, look at Colgan 3407. If it were a 737NG, the same thing could have happened. If it were an A320, the alpha max protection would have prevented it.

So, it's a very difficult debate, and the best solution lies probably somewhere in-between. In my ideal world, all aircraft would have FBW protections, but the pilot would have full intuitive authority (a la Boeing) AND all pilots would have perfect judgment. But that's not the world we live in and AIrbus realizes this. Therefore, in my less than ideal world I think the Airbus philosophy combined with a guarded override switch on flight control inhibitions (alpha protections) is probably the best way to go. The pilot would still have a quick means of taking control, but it is not so physically intuitive, meaning the pilot will have to think rather than simply physically react (see Colgan). I don't think this will happen though, so my current less-than-ideal solution to is fly on trusted reputable carriers as much as possible on aircraft like the 767 which demand more pilot attention and awareness and less systems distraction. I place my faith in the pilots, the pilot training and the safety culture of the operator.

[Joe H]

Evan, thankyou for the very well thought out response.
I take all you say on board.
Please allow me time to consider a response, as it deserves time for that.
I sort of agree and then dont in some areas.
Will respond later..

A very well considered reply, I commend you.

I need to listen to Leonard Cohen for an hour before replying lol...

Nice one !.. but as said, I have some disagreements..
You certainly make people think.. in my case, I have my opinions, but as always, others are valid and may change ones thoughts.

Later... !

[Gabriel]

But, holding that same pitch, if the power is reduced to, say 70% N1, I would expect the plane to lose altitude, as I think it requires something in the neighborhood of 83-95 N1 to maintain altitude at that pitch.

Ah, ok, my bad. I was asking why to your "descending would mean slowing down", my reasoning being that you can perfectly descend and not slow down, and even speed up, but I had missed your "as long as you keep that pitch" part.

[Jpmkam]

Black boxes analysis information.

Investigators who recovered the Airbus flight recorders two years after the Air France crash that killed all 228 people on board are seeking to beat the odds again and reconstruct the final moments of flight 447.

The recorders, one storing flight data and the other cockpit voices and sounds, house several dozen memory chips that may provide clues to modern aviation’s biggest unsolved mystery. The challenge will be to render the material readable after the boxes spent two years at the bottom of the Atlantic Ocean, exposed to corrosive salt water and intense pressure.

“We have no experience in dealing with flight recorders that have been immersed at this kind of depth, so we just don’t know,” said Philippe Plantin de Hugues, a black-box expert with France’s BEA air-accident investigation bureau in Paris.

Seawater is likely to have penetrated the orange cylindrical casings and soaked the critical memory boards, Plantin de Hugues said. One unknown is whether the canisters have been spared from corrosion by the low levels of oxygen 3,900 meters (12,800 feet) below the waves.

After a rinse in de-ionized water to remove salt and other deposits that could cause a short circuit, the electronics are dried in a special oven and inspected under a microscope. If the circuit boards are damaged beyond repair, each memory chip can be detached and read individually, according to the BEA.

“They want to understand what the pilots saw when these problems with airspeed showed up, and how they interpreted that,” said David Learmount, a former U.K. Royal Air Force pilot and safety editor at Flight International. He predicted the investigation will focus on “what they said to each other and what they set about doing.”

The flight data and voice recordings should be retrievable, according to Paul Dujancourt, who works at data-recovery specialist Kroll Ontrack, which helped read information from a hard drive that had fallen 39 miles (63 kilometers) into a lake from the exploding Space Shuttle Columbia in 2003.

Once uploaded to the BEA’s computers, copies of the data are stored on secure drives and in the agency’s safe, while the original black-box media are removed to a police evidence room.

[Black Ram]

BEA Update for May 10:

he flight recorders will be transported to the BEA during the morning of Thursday 12 May 2011. A press briefing will be organised on the BEA’s premises at Le Bourget from 10 h to 12h.


At the briefing Jean-Paul Troadec, the director of the BEA, will be accompanied by Alain Bouillard, Investigator-in-Charge of the safety investigation and Christophe Menez, head of the engineering department.


Mr Philippe Vinogradoff, special representative to the AF 447 families of the victims will be present.


The representatives of the judicial authorities, will also be present at the press briefing. Mr. Jean-Claude Marin, Prosecutor in Paris Court, or his representative, Colonel François Daoust, head of the French forensic institute (IRCGN) and Xavier Mulot, head of the judicial investigation unit of the French Gendarmerie.

[Myndee]

Assuming that no major complications arise with the recorders, how long do you suppose it will take to get back readings? I know that in all liklihood the general public will not know about it until the report is released. I hope that the BEA releases certain parts of the transcript to try to put people at ease. I kind of think they might.

Thanks to all who replied to my poll. My opinion pretty much aligns with most of you. I think the pitots failed for whatever reason and the pilots did not configure correctly for a recovery, and probably didn't have time or clear heads to do so dealing with the warnings, alarms, contridictory information, and the severe weather at hand. This is a change from my initial thought months ago that this was a structural failure. And you say I don't listen.

[Jpmkam]

Judges halt seabed recovery of bodies from Air France jet

The remarkably preserved remains of up to 100 victims of the worst crash in Air France's history must not be recovered from the seabed because it is too traumatic for their families, judges have ruled.

Two bodies still strapped to their seats were last week raised from the wreckage of Air France flight 447, which crashed into the sea two years ago, killing all 228 people on board.

Experts say the victims have been preserved as "waxworks" by the extreme cold, darkness and water pressure 12,800ft below the Atlantic Ocean.

But the two bodies disintegrated while being raised through warmer water and stronger currents to the surface.

Now two Paris judges overseeing the recovery operation have said no more should be brought up from the wreckage.