Recently someone forwarded this article to a mailing list I read. In excerpt:
Jumbo jet packed with British tourists seconds from disaster after it fails to rise on take-off
By Daily Mail Reporter Last updated at 2:21 AM on 01st June 2009
Hundreds of passengers narrowly avoided disaster when their plane nearly crashed after taking off.
The British Airways plane shook violently and did not rise more than 30ft above the ground as it set off from Johannesburg to London.
The pilot has been praised for his quick actions in keeping the Boeing 747 in the air, saving the lives of the 256 passengers on board. Miraculous escape: The British Airways Boeing 747 is thought to have gone into landing mode so that the flaps that make it rise did not work.
Travelling at 200mph, he dumped enough fuel for the aircraft to eventually gain height, before returning it to the airport.
It is believed that a technical fault caused the plane to go into landing mode so that the flaps that normally make it rise did not work.
An investigation is under way as to how the jet came so close to crashing.
A BA spokesman said: 'As a precaution BA56 Johannesburg to Heathrow flight on Monday May 11 returned to the airport shortly after take-off due to a suspected technical problem.
'The Boeing 747 aircraft with 256 passengers on board landed safely and the customers disembarked as normal into the airport.
'We are cooperating fully with the South African aviation safety authority's investigation into the flight.'
Referring to the pilot's quick actions, he added: 'Our crews are trained extensively to deal with all eventualities.'
So "the flaps that make it rise" weren't working. Before reading part on, what would you think this term referred to?
It could be the actual flaps, and there are certainly accidents that result when flaps are mistakenly not extended, but flaps are normally used for landing, so 'going into landing mode' doesn't make sense. If the airplane did get off the ground with no flaps and into level flight, I'd expect it to have accelerated rapidly. They say 200 mph. That's slow, but is it in the slow flight regime for a B747? I don't know. I also don't know which orifice they pulled the 200 mph number out of.
I considered that "the flaps that make it rise" were the two sides of the elevator. It does flap like the flukes of a whale, and certainly when it is raised, the airplane normally pitches up. But operation of the elevator is not suppressed during landing.
I thought also of things like spoilers or leading edge devices: anything tab-shaped that protrudes from the airplane could be a flap. But nothing matched well enough to seem like more than a wild guess.
Fortunately a member of the mailing list found an NTSB report on the flight. Without the identifying details of type, airline and airport I wouldn't even have matched the tabloid story to the report.
On May 11, 2009 at 18:37 UTC, a British Airways Boeing 747, powered by Rolls-Royce RB211-524H2-T engines, experienced a No. 3 thrust reverser unlock light illumination during the takeoff roll from the Tambo International Airport (FAJS - formerly known as Johannesburg International Airport) while the airplane was traveling at 124 knots. The No. 2 engine thrust reverser unlock light came on at 163 knots and just prior to rotation the slats retracted. The airplane rotated and climbed at a 200 foot per minute rate. The flight crew dumped fuel and did an air turn back to FAJS where a safe and uneventful landing was made.
So the flaps that made this particular airplane rise appear to have been the slats, which the NTSB report must be using as a generic term for leading edge lift devices. The B747 uses Krueger flaps instead of slats to modify the wing for takeoff. The Krueger flaps fold out from under the leading edge of the wing, creating a barrier to air incident there. This makes the airflow behave as though the leading edge of the wing were thicker and rounder, just like the wing on an airplane designed to go slowly, thus giving the wing more lift at low speeds.
Mind you, if forced to condense that into six words I'm not sure I'd come up with anything much more meaningful than "the flaps that make it rise." Anyone?
I'm scheduling this to post a week or so after I'm writing it, because everyone is talking about Air France 447 at the moment. Although when you see this, I doubt the voices will have resolved the divided opinions:
- a thunderstorm alone could have done this to a perfectly good airplane
- there must be a flaw in the aircraft for a thunderstorm to do this
- the pilots or the software must have reacted badly to exacerbate the situation
- It was terrorists/a meteor/aliens that did it
People I respect and who are more knowledgeable than I inhabit each of the first three camps, so I'm not putting up my tent anywhere. My traffic is way up from people finding this blog by searching on terms like "coffin corner" and "stall recovery." That means that instead of just talking to the people I hang out with, my regular readers, I'm also addressing a lot of spectators who don't "know" me. I do think it's possible we'll never have a satisfactory answer to what happened on that flight.