flexo
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Overweight No Flaps Landing

Sun Jun 08, 2008 9:57 am

Yesterday I saw a report on TV about the 1992 EL Al 747 crash in Amsterdam (Link: http://aviation-safety.net/database/record.php?id=19921004-2), where both engines on the right side of the aircraft separated from the wing and took almost the entire leading edge with them shortly after take off.

Although the aircraft remained flyable, the stall characteristics of the right wing became worse causing it to stall before the left wing and thus causing the crash when speed was reduced for landing.

They quoted an expert on the show who said that it was impossible to land the aircraft safely and there was nothing the crew could have done after losing both engines and the leading edge of the right wing.

Hence my question: Assuming control of a 747 was still available but you lost the flaps and you had to land immediately after take off being at MTOW.
Has that been tried before? Is there a chance of a successful outcome? What would be your stall speed then?
 
MD11Engineer
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RE: Overweight No Flaps Landing

Sun Jun 08, 2008 1:35 pm

If the pilots land the plane smoothly (and don't smash it on the runway), the only parts of the plane exposed to high stress are the wheel brakes and tyres. Since the brakes have to dissipate the kinetic energy of the plane in form of heat, the can easily overheat, causing the fuse plugs on the wheels to melt, which in turn would deflate the tyres.
The brakes will be VERY hot after such a landing and there will be a lot of time required to let them cool down (possibly assisted by fans blowing cold air over them or a fog of water spray, never a jet of water, which can cause cracking or distortion of landing gear components due to uneven cooling), before an inspection and, possibly a wheel and brake change can be carried out.
We hadsuch a case not too long ago, when a passenger of a 737 collapsed just after take-off to a distant destination and the plane had to land with almost MTOW. We let the brakes cool down for an hour (while the paramedics were treating the passenger), inspected the landing gear and sent it on it's way.

But in the case of the El Al plane, the plane was onlysemicontrollable after the loss of two engines and the leading edge devices on one wing. I don't see achance for it to come down smoothly.

Jan
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tb727
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RE: Overweight No Flaps Landing

Sun Jun 08, 2008 1:38 pm

I don't know if it has happened but I am pretty sure it would do it. It would be pretty fast but there are numbers for it, it's probably a part of certification.
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PhilSquares
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RE: Overweight No Flaps Landing

Sun Jun 08, 2008 1:58 pm

The EL AL flight was at a disadvantage since the crew really didn't know what the configuration was. Had the crew kept their speed up, they would have been fine.

As for the 747/744 doing a no flap, yes it's possible. However, you will run up against the tire limiting speed of 225 knots (varies with mfg).

In real life, if for some reason you had a no flap/no slat configuration (highly unlikely) the first thing you would like to do is reduce weight as much as possible, (read dump fuel) and then land.
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flexo
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RE: Overweight No Flaps Landing

Sun Jun 08, 2008 3:28 pm



Quoting PhilSquares (Reply 3):
In real life, if for some reason you had a no flap/no slat configuration (highly unlikely) the first thing you would like to do is reduce weight as much as possible, (read dump fuel) and then land.

That's what I thought, too. In case of the El Al accident they were at almost MTOW and in the air for about 8 minutes after the problem occured. Why would they not dump as much fuel as possible during those 8 minutes?
 
PGNCS
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RE: Overweight No Flaps Landing

Sun Jun 08, 2008 4:17 pm



Quoting Flexo (Reply 4):


Quoting PhilSquares (Reply 3):
In real life, if for some reason you had a no flap/no slat configuration (highly unlikely) the first thing you would like to do is reduce weight as much as possible, (read dump fuel) and then land.

That's what I thought, too. In case of the El Al accident they were at almost MTOW and in the air for about 8 minutes after the problem occured. Why would they not dump as much fuel as possible during those 8 minutes?

Seems to me like their plate was pretty full in that 8 minutes...

Disclaimer: I have not read the report and don't know definitively that the crew did NOT dump fuel. Perhaps someone can shed some light on that.

Regardless of the situation, it is clear that the crew was unaware of the true status of the aircraft, and performed as well as could possibly be expected under the circumstances. It's always easy to see the solution when you have years to think about it with full knowledge of the facts; it's much more difficult when you are presented with multiple emergencies and incomplete information in a very time-compressed environment.

From the summary linked in the original post:

El Al cargo flight 1862 departed New York-JFK Airport for a flight to Tel Aviv via Amsterdam. The aircraft arrived at Amsterdam at 13:40 for a crew change, cargo processing and refueling. The total amount of cargo was 114.7 tons, gross weight of the aircraft 338.3 tons (21 tons below the maximum allowable). The aircraft taxied out to runway 01L at 17:14 and started the takeoff roll at 17:21. At 17:27:30, as the aircraft was climbing through 6500 feet, the no. 3 engine and pylon separated from the wing in an outward and rearward movement, colliding with the no. 4 engine causing this engine and pylon to separate as well. An emergency was declared and the crew acknowledged their intention to return to Schiphol Airport and reported that they had a no. 3 engine failure and a loss of engine thrust of both no. 3 and 4 engine. At 17:28:57 the Amsterdam Radar controller informed the crew that runway 06 was in use with a 040 deg / 21 knots wind. The crew however requested runway 27 for landing. A straight in approach to runway 27 was not possible because of airplane altitude (5000 feet) and distance to the runway (7 miles). The Amsterdam Arrival controller then instructed the crew to turn right heading 360deg and descend to 2000 feet. During this descending turn the El Al crew reported that the no. 3 and 4 engine were out and that they were having flap problems. Final clearance was given to turn right heading 270 to intercept the final approach course. When it became apparent that the aircraft was going to overshoot the localizer, the controller informed the crew accordingly and directed them to turn to heading 290 to try and intercept the final approach path again. A further instruction was given a 310 heading and descent clearance for 1500 feet. These instructions were acknowledged and the crew added that they were experiencing control problems now as well. While reducing speed in preparation for the final approach, control was lost and the aircraft crashed into an eleven-floor apartment building the Bijlmermeer suburb of Amsterdam.
 
point8six
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RE: Overweight No Flaps Landing

Sun Jun 08, 2008 6:39 pm

The actual flight conditions experienced by the crew will never be known. It is possible to experiment separation of one engine in the simulator - the warnings and vibration are excessive. With two engines separated, I would imagine the vibration would be both disorientating and frightening and it it easy to see why the crew sought an immediate return without fuel-dumping (only 2000kgs per minute).
 
flexo
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RE: Overweight No Flaps Landing

Sun Jun 08, 2008 9:45 pm



Quoting PGNCS (Reply 5):
Regardless of the situation, it is clear that the crew was unaware of the true status of the aircraft, and performed as well as could possibly be expected under the circumstances. It's always easy to see the solution when you have years to think about it with full knowledge of the facts

Hey, I'm not trying to be the know-it-all 16 years later who would have done it all better. The reason I asked is more that I was wondering if dumping would have even been an option for them considering that they were not at altitude and circling over populated area.
 
tdscanuck
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RE: Overweight No Flaps Landing

Sun Jun 08, 2008 11:37 pm



Quoting Flexo (Reply 7):
The reason I asked is more that I was wondering if dumping would have even been an option for them considering that they were not at altitude and circling over populated area.

It's always *an* option...it just might not have been a good one given all the other stuff they had going on at the time. Dumping fuel at low altitude over populated areas has been done before...it's a PR mess, and expensive to clean up, but better than crashing.

Tom.
 
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Jetlagged
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RE: Overweight No Flaps Landing

Mon Jun 09, 2008 2:25 am



Quoting Point8six (Reply 6):
The actual flight conditions experienced by the crew will never be known. It is possible to experiment separation of one engine in the simulator - the warnings and vibration are excessive. With two engines separated, I would imagine the vibration would be both disorientating and frightening and it it easy to see why the crew sought an immediate return without fuel-dumping (only 2000kgs per minute).

There is no reason why engine separation of itself would produce excessive vibration. That's just the way that simulator is programmed. I'm not sure vibration was a factor in this. The crew had no idea the leading edge was so badly damaged. Excessive vibration might have alerted them.

As for fuel dumping, you can't dump much fuel in eight minutes.

Even given the loss of two engines and two hydraulic systems they would still have had alternate (electric) flaps, so may not have been planning a flapless landing. However alternate flaps on a 747 take much longer to extend, so you have to think well ahead. The leading edge damage made the crucial difference, but given better luck they might still have got the aircraft down safely. Had they elected to stay in the air and assessed the problem more fully, who knows what might have happened?

El Al used to put all their 747 crews thought the AMS accident scenario in the simulator. Crashing as a result was not seen as failure, they just wanted to have the crew experience the stress of the situation. That way if it happened again they would be better prepared.
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RE: Overweight No Flaps Landing

Mon Jun 09, 2008 5:28 am



Quoting Jetlagged (Reply 9):
As for fuel dumping, you can't dump much fuel in eight minutes.

And it's not even eight minutes. It's not like the instant they have a problem they start dumping. I don't know exactly how long it would take but there are checklists and procedures to go through. Also they might be busy with more pressing stuff than dumping.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
flexo
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RE: Overweight No Flaps Landing

Mon Jun 09, 2008 6:11 pm

So from what we learned from the accident, if that happened again and the crew were aware of these problems: No flaps and no engines on the right wing, near MTOW.

What would be the best way to proceed? Stay in the air in a greatly damaged aircraft, dump fuel and hope the plane stays aloft long enough or try to perform an overweight landing asap with no flaps?
 
2H4
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RE: Overweight No Flaps Landing

Mon Jun 09, 2008 6:32 pm



Quoting Jetlagged (Reply 9):
As for fuel dumping, you can't dump much fuel in eight minutes.

See, I really need to find a way to make my baggage-dumping concept a reality. Provided bomb-bay-style doors were installed, it would be both cheaper and faster than dumping fuel.

2H4
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zeke
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RE: Overweight No Flaps Landing

Mon Jun 09, 2008 6:53 pm



Quoting Flexo (Thread starter):
Hence my question: Assuming control of a 747 was still available but you lost the flaps and you had to land immediately after take off being at MTOW.

That is a big assumption, the loss of the mass of those engines will have significantly changed the stability and control of the aircraft, that is effectively an instant 10,000 kg change in mass and CG position.

A reduction in airspeed would result in lower control effectiveness, with the CG change, one may need full deflection at a higher airspeed just to maintain control, and fuel dumping may make the CG problem even worse.
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Zuluaviator994
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RE: Overweight No Flaps Landing

Tue Jun 10, 2008 12:58 am



Quoting 2H4 (Reply 12):
it would be both cheaper

I don't know about cheaper, what about repaying all the pax for their lost baggage?  Wink
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3MilesToWRO
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RE: Overweight No Flaps Landing

Tue Jun 10, 2008 10:25 am

I think a passenger can stay with his/her baggage if (s)he wants.
 
dragon6172
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RE: Overweight No Flaps Landing

Tue Jun 10, 2008 10:48 am



Quoting 2H4 (Reply 12):
See, I really need to find a way to make my baggage-dumping concept a reality. Provided bomb-bay-style doors were installed, it would be both cheaper and faster than dumping fuel.

It would be better to have a system that dumps fuel at a higher rate. If you wanted to be liberal with numbers and figure 100lbs per bag, 2 bags per pax, and 400 pax, you end up with 80k in baggage. The difference between MGTOW (870k) and MGLW (630k) is 240k, so you would still be 160k overweight. A dent, but not worthwhile for the extra weight of carrying such a system for a slim chance of use.

I also think people would rather have some jet fuel fall on their houses than have luggage containers raining down. Especially if it was an accidental jettison!!
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2H4
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RE: Overweight No Flaps Landing

Tue Jun 10, 2008 1:05 pm



Quoting ZuluAviator994 (Reply 14):

My theory is that the value of the fuel will soon exceed the cost of reimbursing the passengers for the loss of their bags...  Wink

2H4
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CosmicCruiser
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RE: Overweight No Flaps Landing

Tue Jun 10, 2008 1:33 pm



Quoting 2H4 (Reply 17):
My theory is that the value of the fuel will soon exceed the cost of reimbursing the passengers for the loss of their bags...



Quoting 2H4 (Reply 12):
I really need to find a way to make my baggage-dumping concept a reality. Provided bomb-bay-style doors were installed, it would be both cheaper and faster than dumping fuel.

This post started out about a horrible accident that MAY have been avoided by a quicker/better fuel dump system. But before you get too carried away with bomb bay doors et all, remember that MOST incidents that require fuel dumping are Air Turn Backs that require no necessity for rapid dumping. Very rarely do you have to dump as fast as possible and get back on the ground. Perhaps an inflight fire or as we always saw in the sim a 2 eng failure in a 3 eng jet.

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