February 2009 Archives

There is a lot yet to learn about the Turkish Airlines Boeing 737-800 crash at Schiphol.

Just about everything, in fact.

But this was an accident - like many recently - that was survivable by all, or at least most, of the people on board.

An unconfirmed report in the Turkish English language daily newspaper Hurriyet has just alleged that at least one of the pilots survived the crash, even if he might not have survived rescue.

The imminent week's issue of Flight International reveals that the rescue crews could not get through the anti-hijack security door to the flightdeck, and eventually they had to recover the three pilots' bodies through a hole they cut in the roof.

Is this the scenario rescue crews face in a future accident in which pilots are injured such that they can't either evacuate themselves or operate the flightdeck door?

If so, the designers have some fast work to do to improve this sad legacy of the 9/11 terrorist suicide attacks, because the safety of pilots following an otherwise survivable accident is not a negotiable issue.

And this is not the only disadvantage the cockpit security door has brought to today's airline operations, as any pilots or cabin crew will tell you.

The Turkish Airlines Boeing 737-800 that crashed on final approach to Amsterdam Schiphol on 25 February is the second aircraft in a little more than a year to land short of a runway on approach to a major airport.

The other event involved a British Airways Boeing 777. It landed about 350m short of runway 27L at London Heathrow in January 2008.

The two events may not turn out to have much in common when we finally know the causes, but it's worth looking at the similarities.

Both hulls were badly damaged by the impact with the ground, but there were no fatalities in the case of the British Airways flight and in the Turkish Airlines 737 only a few fatalities among the one hundred and thirty-four people on board.

And, of course, neither aircraft caught fire.

The Turkish 737's hull looks as if the vertical speed at impact was greater than for the 777, which may account for the fatalities that occurred, but it was clearly survivable by most of those on board.

In neither case was the weather on approach - in itself - a challenge for the aircrew, given that they were approaching runways that have first class navigation aids and high intensity approach and runway lighting.

The interim report on the British Airways event says that the reason the crew had to put the aircraft down short of the runway is that, when they called for power, having put the aircraft into landing configuration, the engines didn't respond, so the crew had to steepen the approach to maintain flying speed.

The cause of the engines' failure to respond is believed to have been a temporary restriction to the fuel supply caused by ice crystals in the fuel. If this is confirmed in the final report, it will have been a unique accident cause for modern jet aviation.

As for the Turkish Airlines 737-800, it had been in service for six years, and the -800 is one of the so-called Next-Generation 737s - the latest variant of the long running 737 Series.

So here we have a latest-generation aircraft landing at one of the world's great hub airports in misty weather - but with more than adequate visibility - and somehow it didn't make it to the runway. What happened?

Frankly, nobody knows at this stage. Did this crew suffer a power failure of some kind? We don't know, but certainly the unique circumstances surrounding the long-haul British Airways flight were unlikely to have been repeated in this short-haul case.

Could it have been a birdstrike, like the one that the US Airways Airbus A320 suffered before it ditched in the Hudson recently? Maybe, but we have no evidence right now.

As modern airlines go, Turkish Airlines does not have a good accident record, having experienced two fatal crashes in the last ten years.

They lost a Boeing 737-400 in 1999, and an Avro RJ100 in 2003. The Avro RJ event also occurred on final approach, but in poor visibility.

As  if we needed to be told, things are changing and the outlook is bleak.

But bleak like what?

Thales, which held a big party to launch its new RealitySeven flight simulator range and announce its re-entry into the provision of training support services on 19 February, gathered a massive breadth of global air transport expertise at its huge new plant in Crawley, near London Gatwick airport.

While I was there, here are a few little gems I picked up from various industry sources. They are paraphrased for brevity, but very close to the original quote:

From a very senior executive in one of the world's major aircraft manufacturing organisations: "No, the major airlines don't do their engineering any longer, they just think they do. Very little goes wrong with modern aircraft, and when it does they expect the OEM [original equipment manufacturer) to do the work. This is going to have to stop, and soon."

Will the manufacturer just stop doing the work? "No, we'll do it, but we'll charge for it."

The same exec predicts a significant move by major carriers away from doing all their own maintenance to outsourcing much of it to MRO providers. But the MROs are relying on the OEMs just like the airlines, says the exec, so things are going to have to change there too.

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Now from senior execs in two world-leading flight training organisations (FTO) that both offer everything from ab-initio pilot training to airline type ratings: "There may be plenty of pilots available right now, but as soon as the economic turnaround comes the training industry will not be able to support demand."

There is a fundamental disagreement here between the FTOs' assessment of pilot supply and the major carriers' experience. The latter all said at Thales' party: "Whenever we advertise for applicants we get more - in multiples - than we need."

But they are showing the early signs of doubt about whether that situation can continue forever. One major is considering doing a deal with regionals about seeing pilots through training, then flying in regional short haul and finally joining its own long haul.

Meanwhile at the event, Thales announced its support for customers to help them set up an entire training organisation if that's what they want, not just to provide the simulation.

This seems to be part of a trend among FTOs and training system providers: today (not at the Thales event) UK FTO CTE announced it has gone into contract pilot supply. In the last year or so Oxford Aviation Academy acquired Parc so that it could do the same.

Are future airlines going to employ pilots or train them any more, or just contract them seasonally as required?

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Still at Thales: What is the priority for airlines today? "To be ready for the upturn." What does that mean in terms of preparation? "Surviving the downturn." But I asked about preparation? "It'll be alright on the night."

Early information released by the US National Transportation Safety Board about the Colgan Air Bombardier Dash 8 Q400 that crashed on approach to Buffalo on 12 February made it look as if the agency had more or less decided that icing was the cause.

This is definitely no longer so. Icing now looks like just one factor - maybe not even the most important one - in a more complex series of events and influences. All the information available at present indicates that the icing that night was at worst moderate and perhaps only slight, neither of which would have been a problem for the Q400's icing management systems if they were fully serviceable. They had certainly been selected.

Although circumstantial evidence (classic icing conditions prevailed, the stick-pusher kicked in, the aircraft pitched up rapidly), suggests icing-caused aircraft behaviour, there are still some alternative possibilities that are unresearched. These include the possibility of an aft centre of gravity exacerbated by other factors. The other factors could include the forward movement of the centre of lift on the wings caused by a combination of light ice contamination followed by the deployment of the flaps. Combinations like these cannot be ruled out until the investigation has had time to analyse the accident data they are still collecting.

For that reason I'm disappointed that the NTSB has handed the press a piece of information that has been interpreted by much of the media as meaning that the aircraft crashed because the aircraft was on autopilot when the crew should, in icing conditions, have been flying it manually. That is horrifyingly misleading at this stage.

One thing that this investigation will definitely NOT conclude, when the final report is published, is that the aircraft crashed because it was on autopilot when it went out of control.

Since the outcome of extensive research by the FAA on icing as it affects turboprops following the investigation into the October 1994 crash of an American Eagle ATR72 twin turboprop at Roselawn, Indiana, crews have been advised (not required) to trip out the autopilot in known icing conditions so they are more aware of abnormal or unusual control forces building up.

That is basically a sound piece of advice but it does not guarantee that, just because the pilots are manually controlling the aircraft, they would necessarily be able to prevent the departure from controlled flight of an aircraft whose de-icing systems are being overwhelmed by the prevailing conditions.

Let's also just have a generic look at what icing protection turboprop aircraft have, especially those with only one or two engines. The first point is that it is not as comprehensive and powerful as the systems jets have, because turboprops are so efficient at converting fuel into power to drive the aircraft forward that they have a smaller proportion of engine power left over to generate electricity or provide hot bleed air - the two most commonly used forms of energy used for anti-icing.

The large surfaces that need icing protection on turboprops are the leading edges of the wings, tailplane, and fin. While smaller areas like engine intakes, propeller roots and spinners can be (and some are) anti-iced by electrical heating, achieving that over the large areas would be beyond the capability of the aircraft's electrical generation system.

So the system most turboprops - including the Dash 8 and ATR series - use is the rubber de-icing "boot". These black "boots" that wrap around the leading edges of all the lift-producing surfaces work by employing engine bleed air as economically as possible. The de-icing system provides pulses of pneumatic energy to cause the boots to inflate slightly, then deflate, then re-inflate and so on. This is intended to break off ice that has already formed on the leading edges.

Yes, you did read that correctly: the ice has to form first and then be broken off, and this is called de-icing, not anti-icing.

If the system is operated before ice starts to build up, there is a risk that, when buildup begins, the pulsed inflations of the boot will cause a gap to form between the ice buildup and the deflated boot, so when it re-inflates it has little effect on the ice that can quickly wrap around the entire leading edge to points beyond the boot itself.

So although the system works well if used at the right time, it can have reduced effectiveness if used at the wrong time. Knowing the difference between the right time and the wrong time is difficult because we are talking about weather here, and no two sets of conditions are ever the same.

In the end, turboprop pilots have to take entry into icing conditions even more seriously - in fact much more seriously - than jet pilots do. And one of the things they need to be able to make good decisions is good forecasts and actual weather reports. Avoiding icing conditions if you are unsure of their intensity is the best policy, but if you trust the information you are given and it turns out to be on the optimistic side of inaccurate, you are in trouble.

Icing is, perhaps above all, the weather condition that remains the most unpredictable and uncontrollable, and the airborne systems for dealing with it are still basically the same as they were in the 1950s.

An Aeroflot-Nord pilot flying a Western-built aircraft - a Boeing 737-500 crashed on approach to Perm, Russia, last year because of disorientation. The official report says the accident was at least partly caused by the fact that the Western and Russian artificial horizons (AH) - alternatively known as attitude director indicators (ADI) - work on a completely different psychology.

This captain had spent most of his flying life using the Russian model and crashed using the Western one. Most psychologists argue that the Russian model is more effective. We'll look at why in a moment.

For a pilot properly trained on either AH, they are equally good at providing him/her with clear information about the aircraft's attitude relative to the real horizon when the latter is obscured by night or cloud.

But what if the pilot was brought up for years using the Russian format, then changes to the Western one? Normally no problem, but disorientation almost always begins with some form of distraction away from the instruments, and if the pilot looks back to the AH and sees an attitude he is not expecting, that's when the trouble can start.

Have a look at the picture above of the two AH types, both showing that the aircraft is in a 40deg bank turn to the right. 

We'll start with the Western model, the one on the left, because its visual logic is easier to appreciate. The horizon bar of this AH always mimics where the real horizon is. What the pilot flying sees, as he rolls his aeroplane (and himself, and the whole instrument panel) into a turn to the right, is that the aircraft symbol, which is fixed to the instrument and thus to the real aircraft, stays in the same attitude relative to everything around him in the cockpit. Another way of considering what the pilot sees in this situation, is that the component that moves relative to the pilot (and relative to the cockpit and to the aeroplane symbol) is the horizon bar, which begins tilting to the left. If the real horizon is also visible, that's what it is doing too.

This is where the psychology comes in. It's to do with what appears to be moving relative to the pilot, and what appears stationary relative to the pilot. We'll come back to that psychology after looking at the logic of the Russian AH.

As the pilot flying in, say, a Tupolev Tu-154 rolls into his 40deg bank right turn, he sees the aeroplane symbol moving into a right bank relative to himself and everything around him in the cockpit. That is a very compelling image: the pilot has commanded a right roll, and the aeroplane symbol rolls right relative to him. The potential psychological confusion here occurs if the real horizon is also visible, because the AH horizon bar is clearly not aligned with the real world's horizon; in the Russian version the horizon bar is the component that is fixed to the aeroplane.

The psychology of flying the Russian AH involves imagining the aircraft symbol as a remotely controlled aircraft that you are flying, and you can make it do what you want it to - but you are watching it from the outside. It is more like a computer game. The instrument tells the complete truth about the aeroplane symbol's relationship with the AH horizon bar, so all the pilot has to do to recover to real straight and level flight is to fly the aircraft symbol onto the horizon bar.

When pilots are led astray by the Western AH, the problem usually starts because the pilot is stressed by high workload or, because of distraction, he has already become disorientated.

Imagine that the pilot with a Western AH has commanded a roll to the right, intending to stop at 30deg right bank, gets momentarily distracted, then looks back at the AH and sees the bank passing through 40deg and continuing to roll right. In a moment of panic, if the pilot latches visually onto the AH component that is moving relative to him - the horizon bar - he may try to "fly" the horizon bar instead of the aeroplane symbol. Think of it: relative to him, the horizon bar is rotating left, so if he sees that as the object to be controlled, the result will be control inputs that steepen the roll to the right, and the real aeroplane may enter a spiral dive. The AH will be telling the pilot the truth about the aircraft's attitude, but while he persists in "flying" the roll bar the psychological result can be complete confusion about what is happening.

The advantage of the Russian model is that the pilot is less likely to end up trying to "fly" the horizon bar because the aircraft symbol is more dynamic relative to the pilot's field of view. It is more obviously the component that demands to be controlled.

You don't have to have learned on a Russian AH to misinterpret a Western ADI. Disorientation and stress can lead a western-trained pilot to try to "fly" the horizon bar instead of the aircraft symbol. It's what probably happened, according to the US National Transportation Safety Board, in the case of John F. Kennedy Jr, in 1999. He was flying a private Piper Saratoga at night when he lost control.

In the video mockup of what happened to the Aeroflot-Nord 737, the fatal banked turn was to the left, but the pilot's action followed the classic pattern whereby the roll continued until it became steep and eventually inverted, and the aircraft's nose dropped as a result.

Two television stations, one German and one Swiss, have begun their own investigation in the face of consistent denials by airlines that passengers and crew are routinely exposed to neurotoxins, and have proved that it is true.

I have blogged about this before. And we have investigated the subject ourselves and found it to be true.

Assisted by Tim van Beveren, an investigative journalist who specialises in aviation related technical documentaries ...

...German television network ARD and Schweizer Fernsehen (Swiss Television) have sent journalists on board ordinary flights with different airlines in various aircraft types. Their purpose was to take swabs from surfaces in aircraft cabins and have them scientifically analysed for their content.

The swabs vvere taken from measured surface areas (10 x 10cm) and sent to a laboratory for analysis. In all aeroplanes but one, measurable quantities of the neurotoxin tricresyl phosphate (TCP) were found to be present. Before I let Tim tell the story below, this blog is an appeal for crew and passengers who have reason to believe they have suffered even temporary effects from this and other toxins known to be present from time to time in cabin air to get in touch.

We have set up a forum specifically for this purpose on our community site, Airspace, on which we want pilot, cabin crew, and passengers who suspect they may have been harmed by a cabin air contamination incident to give details of what they have experienced and under what circumstances.

If you want to know more, visit the Global Cabin Air Quality Executive's website.

I'll let Tim tell the story of this investigation by the television companies:

"Within the last month reporters of ARD German Television Network and Schweizer Fernsehen (Swiss Television) secretly collected more then 30 swab samples from leading airlines such as Lufthansa, Swiss, Air Berlin, EasyJet and others. The samples were analyzed at the laboratories of the University of British Columbia, Canada, under the supervision of Professor Christiaan van Netten, a highly renowned toxicologist and expert in this field.

The samples were analyzed for tricresylphosphate (TCP) an organo-phosphate that is contained in modern jet oil as an antiwear additive. TCP is a known neuro-toxin. The manufacturer of the widely used synthetic jet engine oil, Mobil Jet Oil II EXXON warns about the inhalation of oil mist that may cause nervous system effects. But despite hundreds of reports and scientific articles by toxicologists from Australia, the USA and Canada, nothing has been done so far to prevent oil fumes from entering the cabin environment via the bleed air system of modern jet engine airliners. For more than a decade the issue has been controversially discussed in English speaking communities. But it has now gained momentum in Germany, as the first cases became known to the German Cockpit Association where pilots are suing their employers because they lost their licences because of ill health after what they claim were numerous toxic fume events.

"The German Accident Investigation Bureau, the Bundesstelle für Flugunfalluntersuchung (BFU), expressed its concern about the flight safety implications of such events and confirmed ARD that there is an annual average of 10 cases reported to them where crew members were incapacitated following smell or fume events within German registered aircraft. "But it seems that not all pilot reports make their way to the BFU", says BFU investigator Karsten Severin." 

Tim reports the results, and here is just some of what the reporters found:

"Out of 31 samples, 28 were found positive for TCP. The three samples that were negative were all taken from the same aircraft, a year-old Boeing 737-700. The average amount of TCP found was 80 nanograms on a surface area of 10 x 10 centimetres. But higher amounts were found on three different 757s belonging to the German Charter Carrier Condor (part of Thomas Cook Group): on the aircraft registered D-ABOL the measurements were 154.950 nanograms on a 2 x 2 cm surface only. In the cockpit of the same aircraft the measurement taken a week before was slightly above 60,000 nanograms.

"757s have long been suspected of having higher cabin air contamination than other aircraft. Other high values were measured within the samples taken from BAe 146 / AVRO aircraft, operated by Swiss and Eurowings, the latter a subsidiary of Lufthansa. Despite modifications on these aircraft within the last years in an attempt to eliminate the contaminated cabin air events, on both types high amounts of TCP were found: between 244 and 544 nanograms on a 10 x 10 cm surface.

"Neither Swiss nor Lufthansa wanted to comment when being confronted with these findings. Condor issued a written statement saying that the "results may not allow conclusions about the toxicity on board of the sampled aircraft.""