July 2012 Archives

So Richard chose to ask Singapore for a 20nm straight in final approach, starting at 4,000ft, and when he reached that height and achieved the 165 to 168kt indicated airspeed they had calculated for the approach, he carried out a careful manual test of control inputs to see what response the aircraft would give him, and got adequate results. 

So they began the approach, which delivered some chilling moments. One of the most tense for the crew was the nearly two minutes it took for the gear to drop by gravity, deprived as it was of hydraulic power to lower it.

I'll leave the book to tell you what it was like.

And it got even more interesting when the aircraft was on the ground, halted at the upwind end of runway 20C, the lacerated wing tanks spewing fuel into a spreading puddle of kerosine under the left wing, near the near white-hot brakes. Since the aircraft had landed without any further significant damage, and an emergency evacuation would have had many of its own risks, Richard had decided to keep the passengers on board while the fire crews stabilised the situation outside.

The pilots, unexpectedly, had no radio following engine shut-down, so they could not talk to the fire crews. They couldn't understand why the fire crew were standing back for no apparent reason, and were not spraying the leaking fuel with foam or the brakes with water.. 

The problem was that the No 1 engine was still operating at fairly high power, endangering the fire crews, but there were no indications in the flight deck that it had failed to shut down when the crew had carried out all available shut-down actions. The engine was operating autonomously.

So there were 7 long minutes before communications were established, the fire crews were briefed on the problem with the engine, and they started to make the fuel and brakes safe.

Then came the fascinating interplay, with limited communications and long distances involved, between the flight crew, cabin crew, passengers, the airport staff, Qantas crisis management centre, and the worried relatives all over the world watching the drama play out in real time on television screens. It was 1h 50min before the passengers were off the aircraft, and that wasn't the end of the ordeal for any of them.

Much later, after everyone had dispersed, the effects of the ordeal kicked in, and the crews could not have known in advance how they would feel or react.

Do you have the energy for this?

The book will be released on 24 July.

We're still airborne an hour after the engine disintegration. I'm exhausted from empathising with the stress, the confusion, the multi-layered situation facing the pilots, cabin crew, airline and passengers. 

CNN has already reported a possible Qantas loss.Families all over the world are freaking out.

Onboard (believe me, I'm onboard) we're still going through the ECAM (electronic centralised aircraft monitor) phase 4 system status readouts, many of which are having to be rejected as illogical because the system clearly cannot cope with the massive, unforeseeable combination of failures.

Copilot Matt is losing his voice from reading out ECAM checklists. Richard puts it like this: "Matt  was hoarse, he was tired and, like me, he had inverted his logic ['okay so check what the ECAM has to say, but don't necessarily do it']. Finally, as he called out more inoperative systems on page 3, his voice broke and he added, 'whatever'."

Now we've just done the landing performance calculations for an aircraft that has no working slats, no autobrake or antiskid, multiple aileron and spoiler failures, and has a badly damaged left wing. 

Next episode: the approach and landing.

Oh yes, and I sneaked a preview of the final page of the book. Remember Richard was being line-checked? I'll quote him about how that went: "The outcome? I didn't pass."

I'll get back to you in a couple of hours with a verdict, but right now the bits about handling the incident itself have got me gripped.

Back soon...

Once again the BEA, like the US NTSB, the Flight Safety Foundation and many others, is calling for instrument panels to be filmed, so that after an accident we can know, rather than speculate, what information the pilots were presented with. Flight director activity is not recorded on the flight data recorder.

Flight director crossbars should remove from the display whenever an anomaly like unresolved airspeed disparity disconnects the autopilot/autothrust. If the flight management system computers have recognised their limitations and handed back control to the pilots, what are the flight director bars doing pretending they know any better?

Most important, the flight director cross-hairs on the primary flight display are an aircraft-aiming tool that is increasingly irrelevant in an era when pilots, according to airline standard operating procedures, hardly ever touch the controls. 

Yet they are a compulsively attractive tool. If they are there, you will follow them, especially if you are flying manually on the very rare occasion when you find yourself having to go manual in IMC. If you are feeling under-confident and out of practice, and are flying at night with no natural horizon, you will find yourself clutching at those crossed straws, even if they are mis-directing you.

I've said it before: recurrent training should include manual instrument flying refresher time, with the flight director switched off. 

What are the pilots there for if they are no longer able to fly the aircraft when the automatics have failed?

The French air accident investigator, the BEA, has released the final report on the 1 June 2009 AF447 accident.

Because of the atmospheric conditions in the vicinity of the clouds, turbulence increased a little, and ice crystals temporarily blocked the pitot tubes that provide airspeed readings to the pilots. The flight management computer, confused by the disparity in airspeed data it was receiving, disconnected the autopilot as it was designed to do, warning the pilots that they were in control through a raucous audio signal that the crews call the "cavalry charge". 

The copilot, who was flying, reacted by making a control input that raised the nose of the aircraft dramatically, especially considering that its height was already close to the maximum at which the aircraft could fly safely at that weight. The aircraft zoomed upward at 7,000ft/min rate of climb, speed rapidly decreasing, and less than a minute later a stall warning sounded. That was the first of many stall warnings, but the crew acted as if they did not believe them, continuing to climb and thus lose more speed.

As the aircraft slowed and lost the lift from its wings, it started descending and entered a deep stall.  It was eventually falling vertically at more than 3km per minute with the crew still holding its nose high. The BEA says in its report: "The aeroplane went into a sustained stall, signalled by the stall warning and strong buffet. Despite these persistent symptoms, the crew never understood that they were stalling and consequently never applied a recovery manoeuvre."

During the press briefing associated with the report's release today, the BEA said that the crew interpreted the unfamiliar stall buffeting and the high level of unfamiliar aerodynamic noise as indicating an overspeed condition, whereas it was the opposite.

This is what the BEA had to say about why the pilots appeared unable to cope: "The investigation brought to light weaknesses in the two copilots: the inappropriate

inputs by the PF (pilot flying) on the flight controls at high altitude were not noted by the PNF (pilot not flying) through an absence of effective monitoring of the flight path. 

"The stall warning and the buffeting were not identified either. This was probably due to a lack of specific training, although their training was in accordance with regulatory requirements. Manual aeroplane handling cannot be improvised and requires precision and measured inputs on the flight controls. There are other possible situations leading to autopilot disconnection

for which only specific and regular training can provide the skills necessary to ensure the safety of the flight.

"Examination of their last training records and check rides made it clear that the copilots had not been trained for manual aeroplane handling of approach to stall and stall recovery at high altitude."

The BEA made a series of recommendations, but the ones most directly related to the circumstances of this accident were that Airbus should provide the pilots with a direct angle of attack readout, and that training should be widened to take into account manual flying at the edges of the flight envelope, particularly handling the high altitude stalling that AF447 encountered. To make this training effective, the BEA wants simulators to be improved to represent - more accurately than they now do - handling characteristics at the edges of the flight envelope.