Overweight Landing - When is it necessary ?
 

Hi

When does an overweight landing becomes necessary ?

When In non-normal situation is it a must to land as soon as possible even if the weight is above maximum for landing ?

Any references from Boeing / Airbus will be highly appreciated.

Thanks

Zenj

The simple answer is when the risk of staying in the air is greater then the risk of an overweight landing .

An on-board fire.

I suppose there is a perception that if a plane lands overweight that the gear will collapse and the tyres will burst and the brakes will catch on fire. Overweight landings are not inherently a dangerous exercise, they just put a greater than normal stress on the aircraft (but will be within their design limits)

But I'm sure there are much more suitably qualified people than me who can give you some technical details/numbers

I've never seen definitive written guidance on when to land overweight.

For me,

1. uncontrollable fire,
2. some other event where in my judgement landing asap is required,
3. medical emergency, where life is believed to be in danger.

I did an overweight landing back a few years ago on an A320 due to medical emergency. (Passenger heart attack-Doctor said hurry and get on ground.) After the landing and talking to maintenance, they said the big thing is how hard was the landing? If it is over a certain G limit or greater than so many feet per second down then there is a long inspection to do on the aircraft. If you are within the limits it is a visual inspection only.
We did a good landing and had only the visual....I never knew what happened to the pax. I can't remember how much over weight we were but it was at least a few tons.

I only have limited experience with 737-4/500 and A32S. On the 737, OWL was forbidden, unless commander decides otherwise as Capt. Claret describes. On the A320 the situation is the same, but like an icing on a cake, QRH contains an OWL checklist, OW circle-to-land with one engine inoperative data and pilots are trained to do so. That may be course specific The important thing is to make an entry into the tech log because inspection is required. I have been told that unless the touchdown vertical speed was above 460 ft/min (which is rather heavy landing, but maybe my memory fails me) visual inspection will suffice.

At first, I was stunned how "good" the A320 is compared to 737. But if you give it a deeper thought both are certified along the same rules so structural margins could be the same. Maybe all the difference is the manufacturer's decision to equip pilots with a tool to deal with such non-standard situation.

Also, at MTOW and quick landing with 500 kg less A320 comes 16-19% owerweight. I would guess that other small jets are about the same and hence fuel jettisonning is not installed. I wonder what would be the ratio for the widebodies. Is it at all possible to land a 747/340 at MTOW -2t ?

Yes - manual landing, as autoland not recommended above max. landing weight.

I am with Capt. Claret but would upgrade the uncontrollable fire to ANY FIRE. What is "uncontrollable". Do controllable fires put out less toxic fumes/smoke or do less destruction than an uncontroled fire. I ain't hanging round to find out.

Maui

re from captain87
 

I think that an overweight landing is severely dangerous in every sitation on every aircraft ... A pilot can perfectly read on the FCOM (Flight Crew Operations Manual) that the fuel dumping is always recommended until a normal landing weight has been established.
I have studied for A320 type-rating (oral only): for the A319/A320/A321 you can find written on FCOM that the overweight landing is inhibited ... but I personally believe that it cannot be performed on other aircrafts otherwise.
If the a/c manufacturers has fixed the limits, this means that their cannot be ovveriden ...
Regards !!!

As the chaps say above, if you need to do it then do! When you have a cabin fire etc you might as well chuck the manuals out of the window and get it on the deck, that is the priority...I have done 2, one after engine vibratrion and the other medical emergency. On both occasions there was merely an overweight landing inspection to do which takes a couple of hours tops. (NON EVENT). Its all about priorities guys not manuals and beancounters!!

re from captain87
 

Absolutely true !!!

I think the same. But unlikely the flight manuals state the contary: The overweight landing is severely forbidden. Do not attempt to accomplish a landing at weight greater than the MLW (Maximum Landing Weight) ...
I think that in-flight there is no time to think, the only true procedure is to make what you retain true !!! ... obviously into the safety limits !!!

Not strictly true, boeing produce a checklist for overweight landing (certainly on 757/767). Aircraft are certified to land at max TAKE OFF weight with rate of descent of 300fpm (from the dark depths of memory)...obviously you do your best to reduce weight towards max landing weight (dump fuel) but not at the cost of anyones life, for example in medical emergency situation....an overweight landing check will be required subsequently.

Yes you run the risk of tyre burst, cooking brakes etc but thats what long runways and reversers are for!!

cheers

Maybe one of the TP/FTE's on here can fill us in on UK certification limits??

re from captain87
 

Oh yes,
I was refferring to the A320 Family,
I have only a general knowledge of the 767 ...
I do not absolutely put in discussion the existence of the overweight checklists on 767 ... but I'd like to make one question:
Why the 767 is certified to perform an overweight landing and the A320 do not ?
... I think it's purely a question of manufacturers ... Boeing agrees and Airbus disagree etc ...

It's normal that one (FAA or EASA certified) aircraft have to be able to land in every condition, but there is no necessity to say: Aircraft not certified to accomplish an overweight landing ... as the flight manuals state ...
This depends from the situations, it is obvious that if it is possible, the fuel dumping have to be accomplished by the flight crew ...
Question of good sense ...
Regard !

Yeah capt, i have no idea about A320 family, sorry.
My understanding was that it was a UK CAA certification for any aircraft to come onto the UK reg to be able to do this without any untoward problems? Not 100% sure....maybe the TP's will interject!?

cheers

re from captain87
 

No problems !!!
Unfortunately the aeronautic is a complicated matter.
One aircraft differs from another and so the pilots ...
The pilots with specific type-ratings are machines programmed to operate
with the certified type only. So it's impossible to find a good compromise ...
I'm an ATPL Student who is studying for A320 CBT since 6 mounths ...
so I have to apologyze with you for having discussed about a stupid topic like the "overweight landing" with 2 different aircrafts !

Regards from captain87

No problemo its a big topic - quite an interesting one for you when it comes to your command training in a few years.

re from captain87
 

I thank you for your consideration.
I've 19 years ... too young to become captain ? ... what luck !!! ?!

Good bye !!!

“I think that an overweight landing is severely dangerous in every situation on every aircraft.”

Those who think like this may find that they have mistaken beliefs, particularly when the subject is discussed with the manufacturers. Most aircraft type certifications will clear an overweight landing for a touchdown at or less than 6 ft/sec. Although many design safety margins may compromised e.g. wind, drift, brake energy etc, the manoeuvre is perfectly safe; aircraft continue to follow aerodynamic and mechanical laws. The Captains judgement of safety (safety of life) can override AFM limitations – these situations, operations beyond a limit, should trigger additional thoughts about any change of procedure or other mitigating action.
Just remember that the aircraft is heavy, it will involve higher speed and higher energy (V*2). Opportunities for error arise in judging the higher speed and approach path – you may experience an inbuilt bias to slow down to make the landing scene appear normal. The flare manoeuvre, unless specified, should be the same as normal. Remember that the aircraft has taken off at this or a similar weight – the approach and landing capability does not fall off a cliff edge at MLW.

My Information concerning this topic (A320):

- 120 ft/min considered as normal touchdown rate
- 360 ft/min certified up to MTOW (that is the already mentioned 6 ft/sec)
- 600 ft/min certified up to MLW

Extensive inspections required for overweight landings with 360 ft/min or greater.

Beyond that, everything was said already in the posts above (reasons, risks & benefits etc).

re da captain87
 

For A320 the MLW is 61.000 Kg (134.480 lbs) ... with the following attenuating:

"In exceptional cases (in flight turn back or diversion), an immediate landing at weight above maximum landing weight is permitted, provided the pilots follows the overweight landing procedure"

But I'd like to remind that I have said that the overweight landing is always not recommended, and I haven't said that it's impossible ...

... Airbus write in the procedures to consider the use of the overweight checklists in extreme situations only !

Regards

I have got the same data for the 737, I do not remember if it is a JAR requirement rather than specific data for each airplane.