The FlyDubai Crash in Russia.

Flydubai Crash

UPDATE: March 29, 2016

THE WINDSHEAR THEORY that I initially posited (see original post, below) about the crash of FlyDubai flight 981 last week in Rostov-on-Don, appears to have missed the mark. What we’re looking at now, judging from the black box recordings, is two pilots who lost control of their jet during a go-around maneuver, albeit in terrible weather. Why and how this happened I don’t yet understand, and the latest media reports make nothing clear.

The New York Times carried a story on March 26th that was particularly bizarre. The story I’m talking about is the one that describes “switching on” a “stabilizing fin” and how the crew disengaged the “automatic mode,” and so on. It makes little sense to me. What stabilizing fin? And what is “automatic mode”? Automatic mode of what? People have this idea there’s an on/off switch that somehow controls or lands the whole plane. Then there’s this paragraph:

With the fin activated, ‘the elevator is no longer working and the plane practically does not react to the pilot’s control panel,’ the report said. The channel suggested that the pilot could have accidentally hit the button that activated the fin because of his reported chronic fatigue.

The elevator is no longer working? The fin activated? The button? I fly Boeings for a living and I have no idea what the writer is talking about.

The reporter who put this story together did not have an adequate grasp of the topic, and seems to have garbled up whatever insights their sources contributed. I advise you to read it with caution.

Meanwhile I shudder to think how TV news, for its part, is going to further bollix this up. I haven’t got the stomach to watch.

 

March 21,2016

THERE’S LITTLE TO GO ON following the fiery crash of FlyDubai flight 981 in Rostov-on-Don, Russia, last Saturday morning. This is hardly unusual so soon after a major accident, and I’m sure we’ll learn a lot more in the days coming up. A few things, though, to clarify (and complain about):

The plane went down after circling in a lengthy holding pattern in terrible weather, plunging to the ground after initiating what should have been a standard go-around maneuver. Go-arounds, when a plane suddenly climbs away after attempting to land, are often disconcerting for passengers. The abrupt transition from a descent to a rapid climb can be noisy and jarring. But it’s perfectly natural for an airplane, and a straightforward, if work-intensive set of steps for the crew.

Still, could something have gone wrong? Did the pilots bollix this up somehow, resulting in an aerodynamic stall and a subsequent crash? It’s unlikely, but possible.

And/or, did the weather play a role? Much is being made of the windy conditions above Rostov at the time. “By all appearances,” said Vasily Golubev, the governor of the Rostov region, “the cause of the air crash was the strongly gusting wind, approaching a hurricane level.”

Well, sort of, yes and no. High winds, in and of themselves, do not cause a plane to crash. What the governor and many reporters and commentators have been getting at, but never quite arriving at, is the possibility of windshear: that is, a drastic change in the speed or direction of the wind, which can cause a plane to lose critical flying speed. We’re not talking about a momentary change, like you’d get from a gust, but a more prolonged and powerful shift in where the wind is coming from, or how fast it’s blowing. Strong shears, particularly those accompanied by what’s known as a downburst or microburst, are hazardous to planes when flying slowly and when close to the ground, as the Flydubai jet would have been as it prepared to land.

Windshear accidents have become very rare in recent years thanks to better forecasting tools, pilot training and sophisticated onboard warning systems. But the phenomenon is still potentially dangerous, and a powerful shear can’t be ruled out at least as a contributing cause of this crash.

(And one aspect of this story that might develop over time is whether we’ll be seeing more accidents like this in the coming years, as climate change brings on more extreme weather events. Hurricane force winds over Russia in March?)

Video footage of the impact shows what some people have interpreted as flames coming from the jet before it strikes the ground. The video I’ve seen is too grainy to be conclusive, but if indeed those are flames, this wouldn’t necessarily imply that the plane itself was on fire. It’s possible the flames were might be coming from an engine, and were perhaps the result of engine compressor stalls, which could have occurred as the pilots went to maximum power in a futile effort to climb.

Windshear? A go-around that went bad? Some combination of violent weather and human error, perhaps compounded by an automation or mechanical failure? We’ll find out, most likely, soon enough.

 
 

Additional information about windshear and go-arounds can be found in chapters two and three of Cockpit Confidential.

 
Photo credit: Getty Images

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20 Responses to “The FlyDubai Crash in Russia.”
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  1. Speed says:

    Flightglobal has an update.

    Russian investigators have disclosed that a nose-down shift in the horizontal stabiliser on the ill-fated Flydubai Boeing 737-800 occurred as a push input was recorded on the crew control yoke.
    [ … ]
    It states that “simultaneously” with the yoke being pushed in the direction away from the crew, the stabiliser deflected to a 5° nose-down position. The aircraft rapidly pitched down and dived with a pitch exceeding 50°.

    “Subsequent actions of the crew could not prevent the aircraft’s collision with the ground,” says the inquiry.
    https://www.flightglobal.com/news/articles/flydubai-crash-yoke-push-simultaneous-with-stabil-424011/

    Read the above carefully. That the stabiliser (sic) deflected to a five degree nose-down position could refer to the aircraft nose or the nose of the horizontal stabilizer.

    The investigation continues.

    • Wol says:

      Read the above carefully. That the stabilizer deflected to a five degree nose-down position could refer to the aircraft nose or the position of the horizontal stabilizer itself.

      Unless the writer was completely ignorant (now, there’s a novel thought….) it was the stabilizer position. Although the stabilizer does control pitch, it does not actually select any particular attitude, so could not to be said to select 5 degrees nose down pitch.

  2. Caroline says:

    I know some comments have already said this, but what really bothers me is that the plane was not diverted to another airport instead of remaining in a lengthy holding pattern in terrible weather. Being a ‘phobic flyer’ and thus asking many questions, I’ve always been told that in case of, for example,(too)strong winds, the plane will divert to another airport. But this accident seems to invalidate that assurance… What are the rules here?

    • Patrick says:

      It’s true the plane remained in a holding pattern for a lengthy amount of time, but that itself doesn’t explain anything — with the exception of how it may have exacerbated the pilots’ fatigue levels. The plane had enough fuel to continue holding, and presumably weather conditions allowed for a safe approach.

      Those allowable weather conditions aren’t subjective. There are strict visibility parameters, depending on the runway and the type of approach to be flown, and every plane has a maximum allowable crosswind component. If the winds are beyond this value, you aren’t allowed to land.

  3. Speed says:

    The elevator control system in Boeing 737 aircraft is both complex and reliable. Readers can get an idea of the complexity at this link …

    http://www.slideshare.net/theoryce/b737-ng-flight-controls

    The NYT piece may be a poorly translated reference to some part of the system.

    There is an interestingly similar incident described here …
    http://news.aviation-safety.net/2015/03/30/report-frozen-elevator-nearly-puts-boeing-737-800-into-a-stall/

  4. Nicholas Robinson says:

    Sounds pretty clear to me: the fenstrix was too high on the joypler for the Second Pilot to reach, and he must have accidentally nudged the control-interferometer (that gauges the smoke particle acceleration in the Hydrax) and that obviously caused the Pitot tubicles to ice over and cause the torqueting that forced the aircraft down.

    It seems that the First Officer had also called in sick that day . . .

  5. Dan Ullman says:

    Best guesses:
    “stabilizing fin” = Rudder although this still leaves the mystery of switching it on. (“The NTSB reported today that crash was caused by the pilots not switching the Rudder on…”)

    “automatic mode”= autopilot?

    • Dan Ullman says:

      In the very mild defense of the NYT, wherever that report came from, it was likely reported by a Russian stringer who would do fine in a political matter but is without the proper english for a technical issue. That or they ran it through Google Translate.

      • Richard says:

        That is true, albeit the “stringer” is Senior Correspondent for The Moscow Times, per his Wikipedia entry.

        There’s no Comments section for the article, but there’s some contact information on his Twitter home page — https://twitter.com/INechepurenko — for anyone who’d care to refer him here.

        • Dan Ullman says:

          I speak Spanish pretty well. However, if I tried to talk about an aircraft in Spanish I would end up sounding like Randall Munroe’s “Thing Explainer” 🙂

          • Nicholas Robinson says:

            See my cogent explanation above. I think it makes perfect sense, even after running it through Google Translate into Russian, then that into Japanese, then that into French and finally that into NickSpeak.

            Watch out for that Hydrax! It’ll get you every time.

            NB. Flying over Russia is at best . . . erm, *Russian Roulette* . . .

    • Todd says:

      Could they be talking about the yaw damper? Turning this off at low altitude shouldn’t have any adverse effects though. In the jet I used to fly, it was left on for all phases of flight, including take off and landing, but I know in some planes it is turned off just before landing. Anyone know about the 737?

  6. Kevin Brady says:

    “With the fin activated, ‘the elevator is no longer working and the plane practically does not react to the pilot’s control panel,”

    This is hysterical “practically does not react” practically? And what “fin’ has anything to do with the elevator? And the pilots control panel? what is that? instruments, FMS? Hysterical if not so sad for a prestigious publication as the NYT

    On Monday a front page story said there is no common element in terrorist attacks????????? None?

  7. Kevin Brady says:

    Reading this I always come back to Eastern 66, crashing short of runway 22R at JFK, before we knew about “microbursts” The captain of an EAL L1011 went around after approaching prior to 66 and he claimed his altimeter read as low as 5 feet before he started climbing. A PanAm 727 out of New Orleans and Delta L1011 landing DFW met the same fates.

  8. Catherine says:

    I worry that pilots of budget airlines are pressured into taking risks by their employers because of the costs of diverting an aircraft.

    • greenlight says:

      I dunno, I think the pressure is just as high on highly service-oriented airlines to avoid delays because delays annoy passengers

  9. Chip C says:

    Is icing possible, in a situation like this, where they need to do a rapid climb from near-ground level into possibly extreme conditions? As in, faster icing than the wing de-icers can handle?

  10. Nick says:

    Hi Patrick,

    Do you find it curious that they didn’t divert after the first attempt rather than a prolonged hold? I think I read in one of the reports that other flights did divert prior to the accident.

  11. Nick Ananiev says:

    Can these lights on the video footage be just the landing lights turned on? Thanx