More data from Flydubai crash

Russian investigator MAK has revealed that a nose-down push on the Boeing 737-800’s control  column coincided with a nose-down movement of its horizontal stabiliser as the aircraft transitioned from a go-around climb into a steep, high-speed dive to impact.

The aircraft, operating the 19 March scheduled flight FZ981 from Dubai to Rostov-on-Don, Russia, was smashed into tiny pieces by the impact, and there were no survivors among the 62 people on  board.

Earlier the MAK had stated there were no mechanical or systems failures revealed by the flight data recorder, but says it is still recovering components of the aircraft’s longitudinal control system to check there were no undetected anomalies.

The fatal approach to runway 22 took place at night in convective weather and windshear near the airport. MAK says a go-around was initiated at 220m altitude, and the nose-down yoke push and pitch-down motoring of the stabiliser occurred at 900m, while the cloudbase was recorded as 630m.

With each MAK data release, more similarities with the accident involving a Tatarstan Airlines 737-500 crash at Kazan in November 2013 are being revealed.

Flydubai accident update from MAK

Russian accident investigator MAK has released preliminary information from the flight data recorder suggesting that there was no mechanical or aircraft systems fault in the Flydubai Boeing 737-800 at the time it appeared to go out of control and crash on final approach to Rostov on Don (see details in blog entry for 20 March).

Also since the previous blog story was written, video imagery has been released indicating that the final trajectory of the aircraft to impact was a nose-down high speed dive, which matches closely the flight profile of a Tatarstan Airlines 737-500 before it crashed on approach to Kazan, Russia in November 2013 (see also 20 March story for details).

If the MAK confirms these details in a fuller release soon it will highlight a need for the industry to train crews better for all-engines go-around manoeuvres because of the potentially dangerous combination – especially at night or in IMC – of the strong pitch-up moment caused by go-around power from underslung engines, plus “somatogravic illusion” in the pilots. Somatogravic illusion is the feeling induced by rapid forward acceleration that the nose has pitched up when it has not.

Another factor in this lack of crew familiarity with all-engines-go-around risks is believed to be that the go-arounds most practiced during recurrent training involve an engine-out abandoned approach, in which the power, pitch-up moment, climb rate and airspeed acceleration are all much more gentle.

The Flight Safety Foundation has been alerting airlines to this risk for many years now, and some airlines have modified their recurrent training accordingly.

Pilot groups in Dubai are also alleging that crew fatigue may have played a part in this accident. If this is true, it will emerge in the MAK final report.

Flydubai FZ981

A Boeing 737-800 attempts to land in windy weather in the small hours of the morning at Rostov-on-Don, Russia on a runway approach notorious for its windshear .

The crew fails to stabilise the aircraft on its first approach either because of windshear, or because it fails to make visual contact with the runway lights in time for a safe landing, and decides to climb away and circle, waiting for an improvement in the weather.

On its second attempt to approach the same runway – 22 – using a category 1 instrument landing system for guidance, it crashes short of the runway. There was no emergency call.

But this is no ordinary crash of the type that would have occurred if the crew – now under pressure to land because fuel is getting low – had made the decision to continue the descent through decision height, despite not being able to see the runway. If that had been true large sections of the aircraft would have remained intact.

This aircraft hit the ground about 300m short of the runway 22 threshold with such force it was shattered into tiny pieces which were scattered across the airfield. How could that happen?

Information from flight tracking service FlightRadar 24 suggests that the crew also abandoned this second approach, climbing away, but then disappearing.

On 17 November 2013 a Tatarstan Airlines Boeing 737-500, en route from Moscow to Kazan, abandoned a poorly executed night approach at its destination airport, applying full power for a go-around. The nose pitched up to 25deg and the speed rapidly dropped because of the steep climb. The crew, becoming disorientated, pushed the nose down hard, putting the aircraft into a dive at an angle of 75deg just before impact. The aircraft was shattered.

On 12 May 2010 an Afriquiyah Airways Airbus A330-200 carried out a go-around from the approach to Tripoli airport’s runway 09 at dawn, the crew lost control because of disorientation and the aircraft crashed. There was one survivor among the 104 on board.

There have been  many documented cases of crews nearly losing control when carrying out an all-engines-operating go-around.

This does not pretend to be the definitive answer to what happened to Flydubai flight FZ981 on 19 March, but it does pose the question as to what kind of event could cause the wreckage to be so badly fragmented.