davescj
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Fuel, Wt, And Emergency Landing Question

Sat Dec 15, 2007 10:36 am

On one of the threads in Civil Aviation, one of the busted myths is that at the end of a long flight, pilots dump fuel to bring a large get down to a safe landing weight. As was pointed out, not only is this environmentally bad, but expensive with the cost of jet fuel. As a result, use of fuel is calculated in advance. Further, not all planes can dump fuel mid -- air they said.

So my question is if a plane can't dump fuel (as it isn't equipped for example) what does a plane to lower weight to max landing weight if you MUST land immediately after take off (ex: a large bird flies into an engine, as happened to a 757 for Thomas Cook Airways, took of from Manchester, about 15 seconds into take off, bird flies into engine, must now make emergency landing due to loss of an engine, returns to Manchester safely, UTUBE video I am refering to is here

http://www.youtube.com/watch?v=9KhZwsYtNDE ).

In this case, as the gas tanks had been filled to go a couple hours away, obviously they had a good amount of fuel.

Assuming the plane was over max landing weight, what can be done to lower the weight (other than drop fuel manually)? Or can you simply land overweight and deal with that in a seperate manner? But isn't their a point where it is simply to heavy to stop on a runway (ie the proverbial runaway train/18 wheeler effect of interia).

I hope the question made sense.

Thanks for the answers!

Dave
Can I have a mojito on this flight?
 
PhilSquares
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RE: Fuel, Wt, And Emergency Landing Question

Sat Dec 15, 2007 10:47 am

Quoting Davescj (Thread starter):
Or can you simply land overweight and deal with that in a seperate manner? But isn't their a point where it is simply to heavy to stop on a runway (ie the proverbial runaway train/18 wheeler effect of interia).

You just simply land overweight. Here's a section of the Flight Crew Training Manual (FCTM) from the 747-400.

OVERWEIGHT LANDING
Overweight landings may be safely accomplished by using normal landing
procedures and techniques. There are no adverse handling
characteristics associated with overweight landings. Landing distance is
normally less than takeoff distance for flaps 25 or 30 landings at all gross
weights. However, wet or slippery runway field length requirements
should be verified from the landing distance charts in the Performance
Inflight chapter of the QRH. Brake energy limits will not be exceeded for
flaps 25 or 30 landings at all gross weights.
Note: If flaps 30 approach speed (VREF 30 + additives for wind and
gusts) is higher than 167 knots, use flaps 25 and VREF 25 for
landing.
If stopping distance is a concern, reduce the landing weight as much as
possible. At the captain’s discretion, consider fuel jettison or reduce
weight by holding at low altitude with a high drag configuration (gear
down) to achieve maximum fuel burn-off.
Analysis has determined that, when landing at high gross weights at
speeds associated with non-normal procedures requiring flaps set at 25,
maximum effort stops may exceed the brake energy limits. The gross
weights where this condition can occur are well above maximum landing
weights. For these non-normal landings, maximize use of the available
runway for stopping.
Observe flap placard speeds during flap extension and on final approach.
In the holding and approach patterns, maneuvers should be flown at the
normal maneuver speeds.
Note: For overweight landings, flaps up command speed should be set
no lower than VREF + 100.
Use the longest available runway, and consider wind and slope effects.
Where possible avoid landing in tailwinds, on runways with negative slope,
or on runways with less than normal braking conditions. Do not carry
excess airspeed on final. This is especially important when landing during
an engine inoperative or other non-normal condition. At weights above the
maximum landing weight, the final approach maximum wind correction
may be limited by the flap placards and load relief system.
Fly a normal profile. Ensure that a higher than normal rate of descent
does not develop. Do not hold the airplane off waiting for a smooth
landing. Fly the airplane onto the runway at the normal touchdown point.
If a long landing is likely to occur, go-around. After touchdown,
immediately apply maximum reverse thrust using all of the available
runway for stopping to minimize brake temperatures. Do not attempt to
make an early runway turnoff.
Autobrake stopping distance guidance is contained in the Performance
Inflight section of the QRH. If adequate stopping distance is available
based upon approach speed, runway conditions, and runway length, the
recommended autobrake setting should be used.


On the 400, you take off at 397.8(396 744F) Tons and come right back and land even though the MLW is 285.7 (302 744F)

[Edited 2007-12-15 02:59:33]
Fly fast, live slow
 
wilco737
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Joined: Sun Jun 20, 2004 12:21 am

RE: Fuel, Wt, And Emergency Landing Question

Sat Dec 15, 2007 10:50 am

Well, you can and have to do an overweight landing if necessary! If you have a fire on board and need to land ASAP you just do it! Try to achieve a not too hard touchdown, but dont waste any runway because the approach speed will be pretty high due to the high weight...

If you cant dump fuel then you have to circle around until you reached your MLAW (max landing weight). But the question is: how long do you want to circle in a holding pattern on just one engine?

On short haul aircrafts the difference between MTOW and MLAW is not so significant. 737-300 MTOW (at LH) is 57.6tons and MLAW is 52.6. So even if you take off with MTOW and land straight away you have burnt a little fuel already and then most runways are long enough to stop the "small" aircraft on the runway.

On long haul aircrafts the difference between MTOW and MLAW is significant! MD11F is MTOW 285.990 tons and MLAW is 222.900 tons... So if you take off with 286 tons and land straight again, you are for sure overweight! But what will you do when there is fire on board?! LAND that damn thing ASAP on the longest available runway in your closest vicinity!!!

If you have enough time then you can dump fuel of course. Fly to a dumping area, dump the fuel and land without any problems!

WILCO737 (MD11F)
 airplane 
 
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Starlionblue
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RE: Fuel, Wt, And Emergency Landing Question

Sat Dec 15, 2007 12:42 pm



Quoting Davescj (Thread starter):
So my question is if a plane can't dump fuel (as it isn't equipped for example) what does a plane to lower weight to max landing weight if you MUST land immediately after take off (ex: a large bird flies into an engine, as happened to a 757 for Thomas Cook Airways, took of from Manchester, about 15 seconds into take off, bird flies into engine, must now make emergency landing due to loss of an engine, returns to Manchester safely, UTUBE video I am refering to is here

I don't know if that plane really needed to land immediately. I mean, it could have burned off fuel if the pilots had felt that they preferred to lower the weight of the aircraft before landing.

Quoting Davescj (Thread starter):
Assuming the plane was over max landing weight, what can be done to lower the weight (other than drop fuel manually)?

Fly around for a while. Contrary to public belief, most aircraft in the sky don't have fuel dumping capability. It's typically limited to widebodies. This is because, as WILCO737 mentiones, narrowbodies don't have a huge difference between MTOW and MLAW.

Quoting Davescj (Thread starter):
Or can you simply land overweight and deal with that in a seperate manner?

Sure. The aircraft can land overweight. You then have to carry out a check to see that there was no damage.

Quoting Davescj (Thread starter):
But isn't their a point where it is simply to heavy to stop on a runway (ie the proverbial runaway train/18 wheeler effect of interia).

Every single landing means calculating if there is enough runway. Heavier aircraft means longer runway required. There is no critical point where the aircraft can't brake.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
tbanger
Posts: 253
Joined: Tue Jul 27, 2004 6:11 pm

RE: Fuel, Wt, And Emergency Landing Question

Sat Dec 15, 2007 9:53 pm



Quoting Starlionblue (Reply 3):
don't know if that plane really needed to land immediately. I mean, it could have burned off fuel if the pilots had felt that they preferred to lower the weight of the aircraft before landing.

You are right....and it didn't land immediately. The actual flight was around 45 minutes. They held at Wallasey VOR while they ran through the abnormal landing checklist and gave the flight attendants time to do a pax briefing.

The flight took off around 09:15 and by the news report that was out at the time said the flight landed back at MAN at around 10:00am.
 
Viscount724
Posts: 19287
Joined: Thu Oct 12, 2006 7:32 pm

RE: Fuel, Wt, And Emergency Landing Question

Sat Dec 15, 2007 10:07 pm

The JetBlue A320 that diverted to LAX in 2005 with a nose gear problem (wheels cocked sideways) after departure from BUR for JFK circled for about 3 hours burning off fuel before landing.
http://aviation-safety.net/database/record.php?id=20050921-0

You've probably seen one of several videos of that landing.
http://www.youtube.com/watch?v=FoMf7lTpWzU
 
Stealthz
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Joined: Wed Feb 02, 2005 11:43 am

RE: Fuel, Wt, And Emergency Landing Question

Sun Dec 16, 2007 12:02 am



Quoting Viscount724 (Reply 5):
The JetBlue A320 that diverted to LAX in 2005 with a nose gear problem (wheels cocked sideways) after departure from BUR for JFK circled for about 3 hours burning off fuel before landing.

You can afford to do that, that aircraft did not have an inflight emergency, it had a landing issue.

If the aircraft was on fire, or they suspected one you can bet they would not have delayed the landing
If your camera sends text messages, that could explain why your photos are rubbish!
 
SNAFlyboy
Posts: 62
Joined: Thu Oct 18, 2007 5:42 pm

RE: Fuel, Wt, And Emergency Landing Question

Sun Dec 16, 2007 1:34 am

In another thread, 2H4 predicted that, as fuel prices continue to climb, it will actually become more economical for airlines to just dump passenger bags out of the cargo hold in order decrease landing weight rather than dumping the fuel! This would be a particularly helpful practice on those aircraft not equipped with fuel dump systems...  Big grin

Or...you could just do the more logical thing and circle around for a couple of hours. Realistically speaking of course, if you plane is in flames, stressing it with an unusually high landing weight is probably the least of your worries..

~SNAFlyboy
 
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Starlionblue
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Joined: Fri Feb 27, 2004 9:54 pm

RE: Fuel, Wt, And Emergency Landing Question

Sun Dec 16, 2007 2:59 pm



Quoting SNAFlyboy (Reply 7):
Or...you could just do the more logical thing and circle around for a couple of hours. Realistically speaking of course, if you plane is in flames, stressing it with an unusually high landing weight is probably the least of your worries..

Indeed. The central point, I guess, is that landing weight is not the primary consideration when deciding to land now or later. If you have to land immediately, you do, and deal with any overweight issues. If you can land later, you consider weight issues and decide how much later.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Viscount724
Posts: 19287
Joined: Thu Oct 12, 2006 7:32 pm

RE: Fuel, Wt, And Emergency Landing Question

Sun Dec 16, 2007 5:40 pm



Quoting SNAFlyboy (Reply 7):
In another thread, 2H4 predicted that, as fuel prices continue to climb, it will actually become more economical for airlines to just dump passenger bags out of the cargo hold in order decrease landing weight rather than dumping the fuel! This would be a particularly helpful practice on those aircraft not equipped with fuel dump systems...

But the fuel savings could well be offset by the lawsuits and resulting settlements to those whose heads the bags landed on....or roofs they plummeted through, plus the claims by passengers for the ejected bags and their contents.  Smile
 
SNAFlyboy
Posts: 62
Joined: Thu Oct 18, 2007 5:42 pm

RE: Fuel, Wt, And Emergency Landing Question

Sun Dec 16, 2007 8:04 pm



Quoting Starlionblue (Reply 8):
If you have to land immediately, you do, and deal with any overweight issues. If you can land later, you consider weight issues and decide how much later.

Well said! I guess this is pretty much the general point.

Quoting Viscount724 (Reply 9):
But the fuel savings could well be offset by the lawsuits and resulting settlements to those whose heads the bags landed on...

Hmm, good point. I think we failed to take into account the death of bystanders from falling luggage in that last discussion... Oops.  worried 

~SNAFlyboy
 
askr
Posts: 39
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RE: Fuel, Wt, And Emergency Landing Question

Tue Apr 22, 2008 10:45 pm



Quoting Viscount724 (Reply 9):

But the fuel savings could well be offset by the lawsuits and resulting settlements to those whose heads the bags landed on....or roofs they plummeted through, plus the claims by passengers for the ejected bags and their contents.

There should be designated luggage dumping areas - far from populated areas, or over water.
The area could than be designated into two parts, with licenced operators cleaning the each area every second day / week etc.

Unlawful collectors would be subject to legal luggage bombardment with no rights to sue  Wink
ATC-PL Wanabe :) - 2nd application is in... 11 July...
 
Flighty
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Joined: Thu Apr 05, 2007 3:07 am

RE: Fuel, Wt, And Emergency Landing Question

Wed Apr 23, 2008 4:49 pm



Quoting SNAFlyboy (Reply 7):
n another thread, 2H4 predicted that, as fuel prices continue to climb, it will actually become more economical for airlines to just dump passenger bags out of the cargo hold

Or excess F/As  goodvibes 
 
tdscanuck
Posts: 8572
Joined: Wed Jan 11, 2006 7:25 am

RE: Fuel, Wt, And Emergency Landing Question

Thu Apr 24, 2008 7:15 am



Quoting Davescj (Thread starter):
So my question is if a plane can't dump fuel (as it isn't equipped for example) what does a plane to lower weight to max landing weight if you MUST land immediately after take off

Land, deal with the other consequences later.

Keep in mind that there is no inherent reason there will be negative consequences from an overweight landing. That fact that the aircraft took off proves that the gear and airframe can support the aircraft on the ground at the necessary speed. If we assume that the takeoff was per regulations, we know that the aircraft has enough braking power to get up to V1 and then come to a complete stop at MTOW. In the case of the notional landing, you're basically at MTOW but can use the whole runway, not just the part that's left after you accelerate to V1.

Provided you don't smack down on the landing gear and force the oleo's to absorb way more energy than they want to (or bottom out and drive that energy into the structure) the overweight landing shouldn't do any harm to the aircraft, other than probably new tires and brakes because I'd be hitting max autobrake in a situation like that.

Tom
 
Tristarsteve
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RE: Fuel, Wt, And Emergency Landing Question

Thu Apr 24, 2008 3:44 pm



Quoting PhilSquares (Reply 1):
Analysis has determined that, when landing at high gross weights at
speeds associated with non-normal procedures requiring flaps set at 25,
maximum effort stops may exceed the brake energy limits.



Quoting Tdscanuck (Reply 13):
the overweight landing shouldn't do any harm to the aircraft, other than probably new tires and brakes because I'd be hitting max autobrake in a situation like that.

Only seen it once. A B747-200 took off from BAH to SIN, Engine fire warning on rotation. Both bottles fired and the warning remained. So one circle and landed. Parked on our ramp and we went out to it. It was a false warning. The electricain quickly found the fault, I had arrived with two fire bottles to change and all was going well. It looked like we could fix it before the crew went out of hours. Then the fusible plugs started fusing. When the third wheel deflated the service got nightstopped, as we only had two wheels!
 
MD11Engineer
Posts: 13916
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RE: Fuel, Wt, And Emergency Landing Question

Thu Apr 24, 2008 8:32 pm

From a maintenance point of view, we'll have to do an overweight landing inspection. If the pilot greased the plane on the runway and did not allow exessive sink rates to develop, we'll essentially have a look at the wheels and brakes and the plane might be a while on the ground to let the brakes cool down (had it last week, when one of our 737NGs had a medical emergency just after take-off, fueled for a trip from Germany to Morocco, I advised the pilots to wait for an hour with parking brakes released, while the ambulance crew was treating the ill passenger and while his and his family's luggage was recovered from the cargo hold).

If the pilot on the other hand slammed the plane onto the runway, a hard landing inspection will be added. On the 737NG, it consists of two parts. The first stage is a good walkaround with emphasis on the landing gear and gear attachment points, keel beam, engine pylons, fuselage and wing skin for wrinkles, cracks, distortion or damaged rivets, a visual inspection of the aft pressure bulkhead and the area, where the zone aft of the aft pressure bulkhead attaches to the bulkhead. The interior is also checked for e.g. PSUs, which might have come down or loose ceiling panels. If anything is found, the second stage will be initialized, which is in depth inspection of the plane, requiring the opening of access panels and revoval of fairings to get access to the structure.

Jan
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