Egyptair MS804: significance of ACARS messages clarified

Airbus is not, at present, able to give specific advice to A320 operators based on information available from the Egyptair MS804 investigation, according to a report by Flightglobal senior journalist David Kaminski-Morrow.

Data transmitted by the aircraft’s ACARS messaging unit to the Egyptair operations centre is insufficient to point to a cause, he reports, explaining: “Airbus has already informed operators, via two accident information bulletins, that the available data is limited and that the analysis of the transmissions does not contain enough data to determine the accident sequence, Flightglobal has established.”

The Flightglobal report continues: “With the inquiry unable to conclude whether a technical flaw contributed to the crash, the airframer has been unable to provide any immediate advisory to operators.

“Although seven ACARS maintenance messages transmitted in the space of 3min – between 02:26 and 02:29 Egyptian time – hint at the possibility of smoke and heat in the forward fuselage, there is no confirmation that the time-stamp of the messages correlates with the order of the trigger event and no clear indication of the precise time interval between them.”

The unknown factor is the “trigger event” referred to. The ACARS messages (see earlier blog entries) and the circumstances of the crew’s loss of control over the aircraft do not provide specific evidence to indicate either sabotage or a fault as the trigger event.  But whichever it was, it appears to have generated fire that caused progressive electrical failures, and the crew’s loss of control over the aircraft ensued soon after that.

Floating wreckage and body parts recovered from the water where the aircraft crashed into the Mediterranean Sea north of Alexandria, Egypt, so far provide no clue as to whether sabotage or another cause brought the aircraft down. And the search coordinators have released no information about how widely the wreckage field is spread. This can be an indicator of whether the aircraft came down in one piece or had broken up in the sky, but after time the clues can be lost because the floating wreckage can be spread by sea currents and wind.

All this makes the recovery of the main wreckage and the flight data and cockpit voice recorders from the sea bed vital for the understanding of what caused the loss.


Missing Egyptair flight MS804

It’s tempting to speculate that the loss of Egyptair MS804, an A320, was caused by sabotage because that’s what happened to the Metrojet flight out of Sharm el-Sheikh last year.

But, in the last decade, several aircraft have quietly gone missing during cruising flight without being brought down by explosives or in-flight break-up. The most obvious example was an Air France A330 that went missing in the south Atlantic in 2009, but there are others. And there is no information yet which would rule in or rule out either of those scenarios.

Greece’s Defence Minister Panos Kammenos has told a news conference that soon after entering Egyptian airspace, the A320 had turned “90 degrees left and 360 degrees to the right” before descending and disappearing off radar at 15,000ft. If that information is confirmed – and I have no reason to doubt it – the flight had clearly been destabilised, but the cause of the destabilisation is not known.

The aircraft’s last known position is over the Mediterranean south-east of Crete and south-west of Cyprus, but still more than 100nm off Egypt’s northern coast. Fairly soon some useful information is likely to become available because several military units – ships and aircraft – have been committed to a search of the area.

If, for example, there is a floating wreckage field and it is very widely dispersed, it will suggest an in-flight break-up.

But breakup can happen for reasons other than an explosion – although history and modern experience says that’s highly unlikely.

The aircraft and its “black box” recorders are almost certain to be found because, after other aircraft losses in the sea, recorders have been recovered in working condition from deeper waters than this.


Loss of control, loss of nearly 2,000 people in crashes

As the Air Asia Indonesia accident investigators confirm the crash was caused by loss of control following an electrical snag, the tally of people who have died unnecessarily on commercial airliners has taken another step up.

There have now been 18 loss of control accidents since the year 2000, and 1,886 people have died in them because the pilots failed to maintain control of aeroplanes that were completely flyable, and most of which had nothing wrong with them.

The Air Asia accident involved an Airbus A320 at 32,000ft in the cruise over the Java Sea last year on 28 December 2014. The report says an electrical fault – known to the airline and the captain but not resolved – caused an alert to be repeated three times before the captain attempted to resolve the issue by tripping and resetting the circuit breakers for the flight augmentation computers.

The autopilot had been coping with the control effects of the electrical fault, but when the FACs were switched off the autopilot tripped out and left the pilots to fly the aircraft, and they clearly were not ready for that.

The electrical fault was caused by a crack in the solder on a printed circuit board associated with the rudder travel limiter, which prevents the rudder being deflected too far at high speeds. As soon as the autopilot was disconnected, the effect of the fault was to offset the rudder by 2deg, which is not much, but enough to cause the aircraft to roll left to a bank angle of 54deg. Most airliners bank about 20deg (maximum 30deg) for ordinary manoeuvres on commercial flights.

The copilot was flying, and he failed to take action immediately to roll the wings level, so the nose dropped. Some 9sec later when he did roll the wings almost level he also pulled the nose up. Then the bank angle returned to 53deg left, and the pull-up demand on the copilot’s sidestick moved to maximum, actions that suggest the copilot was already seriously disorientated. The aircraft climbed to a maximum height of 38,500ft, stalling on the way.

Once stalled, it descended at a rate of 20,000ft/min into the sea.

The pilots never recovered from the stalled condition. As in the AF447 tragedy the copilot’s nose-up demand – the opposite of what was required to regain control – continued.

There is some evidence that the captain may have left his seat to trip the FAC circuit breakers. At one point in this upset he gave the copilot the confusing instruction to “pull nose-down” (the pilots were different nationalities and neither was a native English speaker), but he then failed to act correctly to take override control with his sidestick.

The industry knows it has this huge weakness in its pilot workforce. The death of 1,886 people since 2000 testifies to it.

There are various components to the problem:

  • highly reliable and accurate automated systems in today’s aircraft mean pilots almost never get the physical or mental exercise of controlling the aircraft and its flight path, so many are not ready when they have to take control;
  • statutory recurrent training requirements are out of date and do not relate to the task of today’s pilots in modern cockpits;
  • most pilots now have no training for recovering aircraft from upsets involving significant attitude deviations from straight and level;
  • most have never handled an aircraft at high level and therefore are not familiar with how small the flight envelope is in thin air, and what to do if the aircraft goes outside the flight envelope (like entering a full stall).

Some airlines, in countries where the aviation authorities allow advanced airlines to vary their training according to evidence of need, the carriers are dealing with this weakness.

But in others where the old recurrent training requirements still dictate training minimums, airlines are still working to the minimums.

And there are even questions about whether, under the stress of aircraft malfunctions or upsets, some pilots’ brains just go all funny and there’s nothing training can do about it. In Toulouse, France, the ISAE is researching this.

Meanwhile, it is a tragedy that, in an industry that is very safe and getting safer, there will inevitably be more of these unnecessary fatal accidents. It only takes the smallest snag to trigger one.