Friends have been asking my opinion regarding the recent Boeing 787 crash in India. Based on the fact that the 787’s gear wasn’t retracting or retracted, the most common speculation right now seems to be that the flight crew mistakenly retracted flaps rather than gear at the “positive rate” point just above the runway.
I’m not typed in the B787 so I can’t say for sure how far apart flaps retraction and rotation speed are. In the CRJ, the following are true:
- the plane won’t take off without some flaps down (i.e., even with full power from two engines it will just go off the end of a 15,000′ runway)
- rotation speed (Vr) and flaps retraction speed (V2+10) are reasonably close, separated by perhaps 15 seconds (admittedly that’s with gear coming up); see “Everything about V Speeds Explained”
- flaps on an airliner move rather slowly
- with two engines at full power, the plane will climb reasonably well even if the configuration isn’t perfect
- given a long runway, less than full power is typically used for takeoff so as to reduce wear on the engines and stretch out the time to overhaul
So… I have no idea what caused this tragedy, but I don’t think that “proper configuration; proper rotation speed; full power; flaps instead of gear just after takeoff” explains a failure to climb. Gear adds drag, but the plane needs to be able to fly in a clean configuration on just one engine and, therefore, with double the power it can easily overpower the gear drag. An inadvertent flap retraction also shouldn’t have caused a crash because, once off the ground, the plane accelerates very quickly toward and beyond V2. The Ahmedabad airport is at sea level and has an 11,500′ runway, which might enable reduced thrust to be used even given the reported 43C temperature. On the other hand, pilots who are sinking would likely push the thrust levers full forward as a reflex.
An obvious explanation is that the aircraft lost power in both engines shortly after takeoff, but it is difficult to think of a way that two turbine engines can fail at the same time. It happened to a Boeing 777 landing at Heathrow due to high altitude icing, but that’s impossible during a hot summer takeoff. It happened to Airbus single-pilot hero Captain Sully (Jeff Skiles nowhere to be found in the media!).
Maybe the fuel was contaminated, but jet engines will burn almost anything and why didn’t the engines quit during taxi?
Separately, should “British man” Vishwash Kumar Ramesh (Guardian) spend all of his future earnings on lottery tickets?
It would be interesting if the survivor listened to all the safety instructions at the beginning of the flight, and followed them to save his life. Is it possible he got out the emergency exit?
I read that he was seatng by the emergency exit and jumped off the plane before it hit the ground and that fire and the pieces of the airplane flew around him. He was found wondering around with a male nurse who got there first. Not sure if true.
As I understand it there were a couple of MD-82 accidents where the plane got off the ground without flaps, and crashed shortly thereafter: Northwest 255 and Spanair 5022.
Is there something fundamentally different between a MD-82 and a 787 or CRJ that would allow the MD-82 to get off the ground without flaps where the others could not?
Coincidently the MD-82 accidents are counter intuitive to me. If you have enough lift to get off the ground why wouldn’t you have enough to stay in the air? Does it have something to do with ground effect? I suspect someone on this blog can explain!
George: Every airplane will fly a lot better within about one wingspan from the ground, as you note, due to ground effect. I’m not sure why heavy jets won’t lift without flaps. Probably it is a tradeoff for their high efficiency in cruise. A low performance airplane will fly off a runway just fine without flaps, maybe a few hundred feet later than if flaps had been used.
@George: If all airports were located on, and took off into, the ocean, then positive rate would be good enough. But in general we have to worry about obstacle clearance; NW255 hit a light pole.
CVR with forensic animation (USE THIS LINK; there are many subsets, but this seems to be the entire video): https://www.youtube.com/watch?v=noADOBnvfZQ
Excellent dramatization of the crash and investigation: https://www.youtube.com/watch?v=O2ELKqvmX6k
Forum chatter indicates that the flaps probably were deployed: the 787’s flaps are more subtle looking than other Boeings, but they do appear to be deployed and they seem to be deployed in the wreckage. Also, the plane appears to have gotten much higher than NW255, and seemed to be flying well until just before it wasn’t. Lastly, most people think that they do not hear engines, but do see and hear the Ram Air Turbine, which would indicate a complete loss of thrust.
https://www.airliners.net/forum/viewtopic.php?f=3&t=1502635
The black box will tell. I think it is almost certainly a power issue (the videos show the airplane flying straight, descending). Do the engines have separate sources of fuel? If that is the case it is hard to see how both lost power. Could it be a loss of electrical power? The engines don’t need electricity to run, but they might depend on controls that depend on electricity.
Anon: The engines do generally have separate sources of fuel (left engine from left tank; right engine from right tank). The magic FADEC controls for the engines are supposed to be 2X or 3X redundant and not need any power from the aircraft (at least one FADEC will have its own engine-driven generator).
Automation is perhaps a suspect. The 787 has autothrottles. Maybe they were somehow configured so that the computers didn’t think the plane needed any thrust. But even in that case pushing the thrust levers forward again (after the autothrottle system pulled them back) should have overridden the computer.
Some forum comments[1] discuss experiencing unusually large amounts of dust in India; perhaps the engines failed due to dirt ingestion.
[1] https://www.airliners.net/forum/viewtopic.php?f=3&t=1502635
After reading your observations about autothrottles, my bet is that the tragedy was caused by some kind of computer failure.
On the other news. I hope you celebrate Trump’s 79 birthday with festivities and watch the parade with your families, a gift from Trump to you all. Make it a memorable day. Enjoy and Cheers …
Thanks, Anon. Our family will, of course, be at the Jupiter, Florida No Kings protest.