Boeing 777 incident at Heathrow!...I'm puzzled?

Question

according to my collection of aviation books!...In the very "Unlikely"event of all engines failing at exactly the same time?...an airliner can glide at a gradient of 1/20 over 100 nauticle miles?(starting at 38,000ft)...using gravity to overcome drag...and can make an emergency landing...also engines are tested for bird strikes and its un-likely to upset "both" engines...and even if it did aircraft can still climb away and return to airport...Volcanic dust in London?...I dont think so...The captain said he had a problem!...a few minutes before?...fuel pumps scaviging maybe?...was this simply a case of "RUN OUT OF FUEL"...because there was no fire!...on impact with the ground...Anybody like to offer any other answers?...

Answer 1

Yes i think so you r right because the plane after landing did not catch fire even after the wing for damaged.

But why then the pilot could have come to know in the cockpit equipment about less fuel.

Anyway everyone is alive.

Answer 2

Nobody is sure what happened yet, but initial reports by the accident investigation board says autothrottle requested more thrust to both engines but when it was applied, nothing happened and . Speculations have included failed avionics, engine failure(though some witnesses said the engines were still turning on impact, though this could be windmilling and the engines might not have been turning, just the wind blowing through it) and contaminated fuel but initial reports kinda points to avionics cus thrust was applied but the plane just didn't acknowledge it.

Answer 3

You certainly can glide if you have enough warning. This plane was on final approach with full flaps so there was a lot of drag and not enough height.

However, another witness said that the engines were roaring so they must have had fuel and power.

I'd be interested to see if the reverse thrust had been actuated by mistake.

Answer 4

One of my first thoughts was wind shear or a micro-burst.  A reporter in a nearby town reported hail which would indicate a possible thunderstorm or some sort of excessive lifting in one place which usually means a down-draft or micro-burst in another.  At 600 feet off the ground at a decent rate on the approach of about 600 feet per minute with the engines running at about idle, if they caught a significant down-draft they would not be able to get the engines spooled up in time to recover.  

Of course it's all speculation and will be interesting to see what really went wrong.  The good news is that everyone survived so we have lots of witnesses.

Answer 5

Definitively, I can't say anything because I wasn't there.

If I had to throw a dart, I'd be willing to wager that for some reason the aircraft lost electrical power, leaving the front seat crew with a few minutes on emergency power, which was used to communicate.

The fuel valves are electrically operated, as are the fuel computers. If one of those two systems fails, egines shut down. Even in no fuel cases, I've never seen both engines shut down simultaneously. In the event of a major power loss, the valves allowing fuel to flow to the engines would shut; simillarly, a loss of electrical power to the fuel computers would kill the engines when fuel flow was cut off.

To carry your theory further, jet fuel has to enter areas where it can be heated enough to ignite and be ignited. From what I saw on the videos, the wing or belly tanks don't seem to be compromised, which would need to happen to cause a fire.

Aircraft with retractable landing gear are designed to belly land if they have to. Hitting the dirt with the gear down, only to have it ripped away, would pretty much be considered a belly landing.

It isn't unprecedented, as videos from www.alexisparkinn.com show; from King Airs to Hawkers, you see pilots doing an incredible job of landing airplaines without power, landing gear, or fires afterwards. I've even witnessed a couple of crashes that didn't result in fire.

(Avgas is more like gasoline and Jet A and Jet A1 are more like diesel or home heating oil.)

That aside out of the way, if a Baron driver can simply forget to put down his gear and plow into a runway with half a load fuel in his tanks, what makes it any more surprising that a sophisticated airliner could suffer an electrical malfunction and still be landed without a fire?

According to the pilot's statement, you might be correct. If there's not any fuel to the engines, the plane falls and makes holes in the ground. In this case, there might be mitigating circumstances and nobody's going to know any more about it until the wreckage is examined.

DGI

Answer 6

The glide ratio you mentioned is applicable in case the engines fail in cruise flight, in clean configuration. This aircraft was low and dirty (gear down, flaps down) so it had a lot of drag working against it.

There was plenty of fuel in the tanks, and as it stands at the moment, the engines are not the problem. if the engines would have failed, there would have been a loss of electrical power in the cabin, and since nobody noticed anything, that is not the case.

The most possible cause at the moment is a fault in the electrical system controlling the engine output. according to the pilots, the engines were working, but they would not spool up when commanded to.

Answer 7

At this point in time it is too early to speculate as to the cause.The aircraft was fairly intact and the flight data recorder is intact, so we should know the reason fairly quickly.The flight data recorders and computers on today's airplanes record alot of data on every flight parameter.

Answer 8

It was about 2 minutes out and probably less than 1,000 ft when the autothrottle 'appeared' not to respond to an increase power demand...

Despite other assertions, it was extremely squally in the Home Counties Thursday lunchtime, so a high demand for energy due to adverse windshear is quite likely...

Why nothing happened is the question...

NB. With landing flap and undercarriage down you would not get a glide ratio of 1:20 out of a modern airliner!

Additionally it wold also be flying somewhat 'on the back of the drag curve' e.g. not at best glide angle speed.

The only response to maintain adegate margin over stall speed so late in the approach would be to dive at the perimeter and then convert that speed over the fence to reduced sink rate by flaring heavily.....  

This is what the 2nd officer (handling at the time) did... a VERY close shave!

Answer 9

I'm just guessing, as the other people have correctly stated that the FDR, or flight data recorder will have all of this information.  However, the 777 is a very computer driven aircraft, and if something were to cause a power outage or surge in the onboard computers that control the engines, this could have caused the problem.  They could still be running, but not able to increase power due to a problem with the throttles.  It may be a fly by wire system, and the computer that controls the fuel metering may have malfunctioned.  I know this is unlikely in both engines, but stranger things have happened.  I guess they were lucky that it happened so close to the airport and not out over the ocean somewhere.  I wonder if the 777 as an air driven generator, which is a device that pops out when you have a power failure, and uses ram air to drive a propeller to make electrical power.  I know that Airbuses have them, as well as many of the newer regional jets.

Answer 10

It's all based on varying degrees of performance margins and in this case nothing has been determined as cause and circumstance until accident investigators come up with some concrete answers, until then I'm not going to speculate on what was the cause of this particular incident. What I do know however is that RR Trent 892 powerplants provide roughly 95,000 lbs. of thrust which is what BA uses on their 777's and they have an excellent service industry record, so it will be interesting to see what was the cause here.....

Answer 11

It's a very curious crash and I look forward to the results of the investigation. Such a sudden drop of altitude like that leads me to believe of some type of enviromental problem like downdraft. If the aircraft lost all power, it wouldnt drop like that, but rather glide. A mechanical issue may be at play too. For instance, if the flaps were extended and a pitch up would radically drop altitude like that