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-   -   B777 single engine overweight landing question. (https://www.pprune.org/tech-log/618698-b777-single-engine-overweight-landing-question.html)

Cropduster 22nd Feb 2019 22:45

B777 single engine overweight landing question.
 
Saw something in a sim the other day that got me thinking and would like others thoughts on it.
Scenario was a simple engine failure in cruise at a weight of about 300 tons. One crew member wanted to dump fuel to landing weight, one wanted to land at current weight to save fuel and environmental damage. Runway was long enough to theoretically allow landing without blowing the tires (but barely) and aircraft was WAT capable of single engine go around.
So while I was siding with the more conservative course of action, are there any certification or technical issues with an overweight single engine landing?

Thanks, Cropduster.

B2N2 23rd Feb 2019 01:21

Dump the fuel and land below max weight.

extreme P 23rd Feb 2019 02:45

Plan to land at the nearest suitable airport?

Chesty Morgan 23rd Feb 2019 03:03

...doesn't mean land immediately.

extreme P 23rd Feb 2019 03:10


Originally Posted by Chesty Morgan (Post 10398069)
...doesn't mean land immediately.

What does it mean then?

Chesty Morgan 23rd Feb 2019 03:36

It means land at the nearest suitable airport.

When it says land immediately that means land immediately.

harrryw 23rd Feb 2019 04:11


stilton 23rd Feb 2019 06:53

Our operations manual specifically prohibits
this, with an engine failure (time allowing) dump to max landing weight


Saving fuel in this situation is a non starter

dixi188 23rd Feb 2019 08:42

Overweight landing only when you have no time to dump!
Why cook the brakes and tyres?

wiggy 23rd Feb 2019 09:10


Originally Posted by dixi188 (Post 10398214)
Overweight landing only when you have no time to dump!
Why cook the brakes and tyres?

FWIW I’ll throw this into the debate - one of “our” triples suffered an interesting engine (as in not just a run down) failure in the cruise recently, whilst well over FCOM max landing weight.

Diversion to nearest suitable commenced...fuel dumping commenced..at which point the Fuel jettison system failed.

After suitable review (nature of the engine failure, performance, etc) the crew made the decision to land above max landing weight.

All ended well, aircraft checked out for overweight landing, nothing adverse found
as a result of the landing but the engine was a mess.

Company completely supportive of crew actions/decisions.


safetypee 23rd Feb 2019 12:40

No obvious certification reasons.
O-Wt landing would not be higher than max takeoff wt; brakes etc are certificated and tested for max wt RTO. Thus brakes and tyre care is not an issue; your are not going to have a quick turnaround !

Time wise; land as you judge the urgency of the situation; according to the situation as assessed, at that time by the people there.

Weight; reduce wt to maximise safety as judged by the landing distance margin vs possible need to make several approaches / divert. Don’t box yourself in to making a ‘first time’ approach and landing which probably has ‘not be done before’ - simulator may not count for much in a real emergency; the aircraft may be the same, you are not.

Dump for the ‘environment’ ! Only if woods / wild life, fish stocks, or fuel tanks are in the overrun area.
Relatives will not thank you for planning a ‘Green funeral’.

ManaAdaSystem 23rd Feb 2019 16:36


Originally Posted by stilton (Post 10398150)
Our operations manual specifically prohibits
this, with an engine failure (time allowing) dump to max landing weight


Saving fuel in this situation is a non starter

Interesting. So if you take off at max TOW, get an engine failure at rotation, your company tells you to hold on one engine while dumping fuel down to max landing weight?
I don’t fly the 777 so how much holding time will this take?
I’m not sure your local CAA/FAA will agree wih your company.

Or did I read you wrong? You would dump as much fuel as possible and land at whatever weight you end up with on your way to your diversion field? Which is what I imagine most pilots would do.

wiggy 23rd Feb 2019 16:57

Given that on e.g. -300 you can be departing 90’ish tonnes above max landing weight I’m also pretty sure the CAA/FAA wouldn’t be too impressed with a once around the pattern and land for a simple engine failure either.

FlightDetent 23rd Feb 2019 17:42

Yikes, what else would they like to see? Fly out 60 miles to a fuel dump racetrack, spend 25 mins there and come back, does not sound too smart.

The AC is certified for an RTO with about 1000 m remaining to the stop. After an engine fails we do our thing, put all of the runway in front of the nose again, and land the ailing bird. Is that scenario any different for a heavy?

If it will take off, you can land it - my predecessors claim to bring that rule of thumb directly from Seattle - a certification requirement they said.

With a cargo smoke warning, we would be landing PDQ as the safest course of action. I do not see how a -1 engine makes that a less professional choice.

Ready to be educated, FD.

Check Airman 23rd Feb 2019 18:17


Originally Posted by wiggy (Post 10398228)


FWIW I’ll throw this into the debate - one of “our” triples suffered an interesting engine (as in not just a run down) failure in the cruise recently, whilst well over FCOM max landing weight.

Diversion to nearest suitable commenced...fuel dumping commenced..at which point the Fuel jettison system failed.

After suitable review (nature of the engine failure, performance, etc) the crew made the decision to land above max landing weight.

All ended well, aircraft checked out for overweight landing, nothing adverse found
as a result of the landing but the engine was a mess.

Company completely supportive of crew actions/decisions.


In fairness, with the jettison system inop, they didn't really have much of a choice, now did they? ;)

To add to the debate, what does the MEL say about having the jettison system inop? That may give some insight into what Boeing thinks.

Disclaimer- I've never flown an airplane capable of dumping fuel.

Good Business Sense 23rd Feb 2019 18:58


Originally Posted by wiggy (Post 10398228)


FWIW I’ll throw this into the debate - one of “our” triples suffered an interesting engine (as in not just a run down) failure in the cruise recently, whilst well over FCOM max landing weight.

Diversion to nearest suitable commenced...fuel dumping commenced..at which point the Fuel jettison system failed.

After suitable review (nature of the engine failure, performance, etc) the crew made the decision to land above max landing weight.

All ended well, aircraft checked out for overweight landing, nothing adverse found
as a result of the landing but the engine was a mess.

Company completely supportive of crew actions/decisions.


Yep - keep doing sensible, safe things as you receive each challenge. If you can, it's good to avoid a high speed landing but you need to balance it all up with what else is going on.

A Cathay Pacific 747-400 taking-off out of the old Kai Tak airport in 1995, on runway 13 out to sea, had an engine blow up, remained on fire in a big way - Captain did a 180 and landed back on runway 31 at 400 tones with 421 on board (max take-off weight) - as they did the 180 the two guys in the back did the performance sums etc etc etc (know your charts well I guess) - all this in around 11 minutes. Amazing ! NEEDS MUST !

I always found the ROD on final approach at those high speeds scary :-)

clark y 23rd Feb 2019 19:52

Personally, I don't like the idea of sitting in the sky in a 300t single engine aircraft any longer than I have to.

tdracer 23rd Feb 2019 20:25

During certification, we look at something called "Return to Land" - basically there is a serious emergency shortly after a Max Weight TO (e.g. uncontrollable fire), and you need to land ASAP - significant fuel dumping is not an option. It may not be pretty, and you want the pilots to be on their 'A' game, but it's required to be possible (and safe) to do a MTOW landing at the departure airport (since you just left there at MTOW, it presumably has a reasonably long runway). This of course assumes that whatever went wrong didn't significantly affect landing/stopping distances.

Personally I've been on a enough overweight landings during flight testing that I don't really see it as being that big of deal so long as the pilots know what they're doing and you're not talking something like a short and/or contaminated/slick runway.

Good Business Sense 23rd Feb 2019 20:59


Originally Posted by clark y (Post 10398642)
Personally, I don't like the idea of sitting in the sky in a 300t single engine aircraft any longer than I have to.

I got used to it after the first couple of times !

wiggy 24th Feb 2019 06:16

Boeing’s thoughts here, (probably based on some of the testing tdracer was involved in):

https://www.boeing.com/commercial/ae...icle_03_1.html


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