Minimum Takeoff Weight?
 

Morning guys,

had a discussion with a friend just right now about some weight limitations of an Airbus and a Boeing.
Does anyone of you know, if a Boeing has an Minimum takeoff weight? If yes, is that not similar to the DOW?

Hmmm; never heard of one.

Minimum weight for take-off
 

The only minimum weight would be aircraft empty weight, plus minimum crew weight, plus minimum fuel for anticipated flight. There is no "Minimum Weight for Take-off" limit of which I am aware. I think your friend is "having a lend of you".

Okay great, thanks guys.
Found something similar for the Airbus in our OM.

On the 777 2 section Perf Dispatch there is a table with minimum weights (alt vs temp). Note that the FMS will not issue Vspeeds at these weights. About 50klbs from DOW.

Certain certification cases require consideration of a minimum flight weight (VMC is one). Depending on how the OEM does it, they may use a minimum flight weight for these purposes which is so low as to be no practical limit on the aircraft; however, this will impose some penalty on normal operations in certain cases, as the weight used may be unrealistically low. There may be cases where the weight assumed is actually greater than, say, the weight which an aircraft with no interior completion and minimum fuel.crew could be at. In that case one would have to arrange the loading and planning to respect the minimum flight weight. However, this would be a landing consideration, and the takeoff would be derived from that, not a direct l;imitation.

There most certinly is: "Minimum Weight for Take-off" would be the operational empty weight plus just enough fuel for get the wheels off the ground.

Yeah, it s certification issues. In low weights you need also to derate and not use full thrust otherwise it's going to be a 360 if one engine quit.

And what about weight and balance?

Try MIN Zero Fuel Weight! And the reason for such a defined limitation ......so the graphs don't have to extend down to zero.

Houba - pray what on earth are you talking about now? I presume that you are making an obscure reference to how Vmcg may be a limiting factor. As V1 should not be less than Vmcg, this is not relevant to the question being asked.

For the Bus
 

A318/319/320/321 - FCOM 3.01.28 pag. 2 - on top
MINIMUM FUEL QUANTITY FOR TAKE OFF : 1500 kg (3307 lb)

A330 - FCOM 3.01.28 pag. 1 - bottom
MINIMUM FUEL QUANTITY FOR TAKE OFF : 5200 kg (11460 lb)

According those minimum requirements the minimum weight would be aircraft empty weight, plus minimum crew weight, plus the above figure.

Confusing multiple issues here ..

The question relates to certification as it is referring to limitations ... MFS has the usual story in his post .. which is not surprising considering that he is a certification man. If there is a declared minimum TOW limitation it ought to be in the limitations section but will certainly be explicit in the CG envelope as shown, typically, by a line across the bottom of the envelope at the relevant weight.

In general, pilots would not have any particular knowledge of this sort of limitation as, in the great majority of cases, it is irrelevant to routine operations.

For a practical consideration, the lightest TOW for a given aircraft will be for a stripped configuration, nil payload, min fuel and crew ... but this is not a limitation .. only a consequence of the configuration.

The BBJ 1 (B737-700 fuselage essentially) has a minimum take-off weight if you try to use 27K engines and no thrust reduction.

The B767-300 I fly has a MIW (minimum in-flight weight) of 81,195 kgs in the limitations section of the ops manual. It doesn't say why though, it would be pretty much an empty aeroplane plus minimum fuel, if any.

I flew B707s years ago and there was also a stated minimum in-flight flaps up weight in the ops manual.

Regards,
BH.

You remember well.
The B707 had a minimum in flight (departure) weight due to the possibility of fuel tank outlet un-porting, during rotation.
Minimum fuel for dispatch...40,000 pounds.

Bangladesh Bimin found out the hard way about this during a takeoff ex- Paya Lebar in the late seventies, just after rotation with minimal fuel in tanks (destination KUL)...three of four engines flamed out, and they ended up in the grass, just off the side of the runway.:uhoh:

post #14, Capt Chambo is quite correct!

We have the B737-700 IGW airplanes, with 27K engines.

I believe some aircraft do have minimum weights, and it could have to do with structural limitations. My guess would be a weight too light could incur structural issues when dealing with increased loading. For example a weight too light could expose the aircraft to excessive loading prior to a stall say inadvertently entering an area of severe or possibly extreme turbulence. This is just a guess on my part. An aircraft designer/engineer may be able to shed some light.

While not EXACTLY a min TOW, the B744 has a min in flight weight, 170,460Kg for Charlie Q operations. Utterly pointless limitation, no BEW is less than 180,000Kg, but in the manuals though. Our GE B744 does not have this limitation.

Some aircraft that PSEU's have a min ops weight, so as the PSEU target far/target near logic can be met.

would the min TO or Landing wt not effect the braking efficiency due to less normal load, insufficient drag to actually fly the ac into Grd effect or increase float to unacceptable limits or the likes?

Just speculating...

The min takeoff weights on the b737-700igw for different engine de-rates (the heavier you are the more engine power you're allowed) relate to amount of rudder force available during a takeoff with an engine failure. The short body and the big engines mean that you're at risk of losing directional control both on the ground and in flight if you exceed the allowed de-rate. So don't push that thrust levers past the green caret unless you're above your flap maneuver speed.

Some limit regarding min wt for Autoland would dictate a min to wt if one intends to do auto land etc....

Very light sectors on the EMB-145 required ballast in the aft cargo area, especially if the catering trolleys were not loaded

Vmca and Vmcg accepted..

our B737-700 IGW airplanes are restricted with 88,900 lbs (40,325 kgs) limitation on Minimum Flight Weight...

mainly for the pitch attitude required to maintain V2 ++, and the comfort factor with such an unusually high attitude.

Cheers...FD...:ooh:

On many of the Citation models, flying Single pilot under the exemption, something not really anticipated by the designers...was an extreme aft CG, sometimes out of limits...some charts in the nose (20lbs) can get it back in...but it was anticipated that two 175lb + pilots were up front as minimum required crew, vs one 200 lb guy.....anther ballast type of thing....R22 helo needs balast if the pilot weighs to little, mainly to give the helo more required weight for a good autorotation....

was an extreme aft CG, sometimes out of limits

not the OEM's problem .. the AFM specifies the limits .. the pilot is required to make sure that they are observed. If this requires ballasting so be it.

B77W Min TOW?
 

Hey guys, my first ever post on PPRuNe. :)I've heard from a source that the B77W (777-300ER), has a minimum takeoff weight! Is this true? This is for safety reasons, apparently. If one eng were to cut-out during rotation, the yaw-rate induced would be quite severe. Hence the requirement. This is what I've heard. Would be great if any of you could shed some light into this.

Thanks,
Cheers!

The 777 minimum take-off weight is mainly an issue for the 77F (freighter).

This is simply because the freighter has a much lower Dry Operating Weight than it's equivalent passenger model (200LR).

Combine a low DOW with those extremely powerful 110 k engines (which have been shown to be capable of 127 k :eek:) and you have a situation where Vmca can be exceeded in the event of an engine seizure - obviously not an option!

Therefore you must either load fuel or ballast to bring the aircraft up to it's minimum TOW.

Here at EK I think we have a minimum TOW of about 170 tons versus a max TOW of about 350t. Would check the books but I'm supposed to be doing the washing-up while the wife's out. :suspect:

Haha! Thank you for your input, really appreciated.:)

Mr 777

Welcome aboard! And THANKS for using the search to resurrect this old thread on a subject you were inquiring about. :D

GF

Minimum flight weight
 

Been there, done that...:
http://www.pprune.org/tech-log/36113...eight-why.html

The A330 I fly has a minimum weight of 125000 KG not only for take off but also for all flight phases. If the ZFW is less than that, any fuel between those weights is basically unusable. Airbus don't say why...

For my 737 I found a " minimum flight weight",38555kg, u can faund it in mass & balance manual..:ok: