Question For You Mainline Pilots

[ItsJustAJob]

What is a S1-S3 do you mean A1-A6 or P1-P4 .S1 thur S7 is non-rev priorities

Yes...sorry...A1-A3....haven't actually used the j/s on mainline for a few years. No mainline flights into MSP (going East).

 

[BoeingBoy]

So captains authority exist in your contract to allow jumpseats to exceed ZFW/MTW due to taxi burn? I ask this question because I have never seen it exercise before. Mainline all the time

john john,

When you're talking about certificated maximum ZFW or MTW, that's a different issue since you're dealing with aircraft structural limits - can't waive those (but in 26 years of flying the 737-200/300/400 around the eastern half the country and 727 on transcons, structural ZFW or T/O weight has never been an issue). The issue is MTW for a particular day and runway - then we can offset the J/S weight with taxi burn. While it's not spelled out, if the limiting factor for T/O weight is landing weight, that really gives one until landing to burn the extra fuel.

Wait a second. Say you are at max take-off weight which is limited by landing weight. Say all fuel is required due to wx, etc. And let's say you exceed your planned ZFW. Heavy weight, short flight, lousy weather.

luvn737s,

I suppose that could be a problem with longer flights. If so, your hands are tied - can't break the FAR requirements.

That said, and at least on the 737, the dispatcher puts some "pad" fuel on 99% of the time - usually for unknown contingencies - and it's on top of minimum fuel at the runway (minimum T/O fuel). We can burn into that without going below minimum T/O fuel.

And of course, tanker fuel is also on top of minimum T/O fuel and we do a ton of tankering on the 737. Just in April I had 4 occasions where we found that we were going to be over max landing wt on arrival due to tankering fuel - ATC shortcuts, etc (plus exceptional airmanship ) On those occasions, we just burned some extra fuel during the last 30 minutes of the flight.

Jim

 

[john john]

dealing with aircraft structural limits - can't waive those offset J/S weight with taxi burn.

Sorry I should have said
So captains authority exist in your contract to allow the aircraft to leave the gate with an jumpseater and exceed ZFW/MTW and allow taxi burn to offset the weight.

 

[BoeingBoy]

So captains authority exist in your contract to allow the aircraft to leave the gate with an jumpseater and exceed ZFW/MTW and allow taxi burn to offset the weight.

Maximum ZFW is a structural limit - a "hard" limit if you like - and can't be wiggled out of. So if the airplane should be at that weight withoug the J/S rider, there's nothing that can be done (other than a couple of possibilities). Like I said, in 26 years I've never seen the maximum ZFW come into play - doesn't mean it couldn't, though.

MTW, on the other hand, could be one of several things.

- There's the structural MTW which is an aircraft limit (and on the 737-300/400 it's 500# less than the maximum ramp weight to allow for taxi fuel). Assuming that the J/S rider's weight didn't result in going over MRW (a no-no), all one has to do is burn enough taxi fuel to be at structural MTW before T/O and have the required T/O fuel.

- There's MTW for the planned runway - in other words, the limit is the T/O runway considering temp, winds, etc and not the structural limit on landing weight. All one has to do is burn enough taxi fuel to reach that weight before T/O. Adding a J/S rider just means burning an extra 185# of fuel on taxi.

- Finally, there's MTW based on maximum structural landing weight - this is the one I'm seeing fairly often with all the fuel tankering we do on the 737. While the LOA discusses burning the extra fuel on taxi, in reality one has till touchdown to reach the structural landing limit (assuming one of the other reasons for the T/O weight limit doesn't also apply).

Of course, there's the situation that luvn737s pointed out - you have just enough taxi fuel to reach the runway and still have the required T/O fuel and you're going to be at maximum T/O weight. Then you get into crzipilot's post - work with the dispatcher to lower minimum T/O fuel. If the dispatcher is agreeable, everything's fine & dandy - the extra weight can be compensated for with extra taxi burn. If not, there's a couple of other things that can be possible. Any children on the flight so that child weights can be used for W&B? Is there another runway that would give a higher T/O weight. Different T/O flap setting? No-bleed T/O if it hasn't already been factored in?

Jim

 

[luvn737s]

luvn737s,

I suppose that could be a problem with longer flights. If so, your hands are tied - can't break the FAR requirements.

That said, and at least on the 737, the dispatcher puts some "pad" fuel on 99% of the time - usually for unknown contingencies - and it's on top of minimum fuel at the runway (minimum T/O fuel). We can burn into that without going below minimum T/O fuel.

And of course, tanker fuel is also on top of minimum T/O fuel and we do a ton of tankering on the 737. Just in April I had 4 occasions where we found that we were going to be over max landing wt on arrival due to tankering fuel - ATC shortcuts, etc (plus exceptional airmanship ) On those occasions, we just burned some extra fuel during the last 30 minutes of the flight.

Jim

Actually the scenario I painted is for very short flights which have an alternate required so that you are carrying more than usual fuel, but all of it is required. The pad you speak of (1000 lbs in our case) is added so that the planned ZFW can be exceeded without needing an amended release (i.e. airplane is heavier than planned {even by 1 #} so it burns more fuel). So if you go over planned ZFW now you need that pad.

Obviously you have to land below MLW, but you can't takeoff at a weight that projects you to land above MLW according to the flight plan either. There may also be weight issues related to balked landing performance (SNA is big for this) and max weights related to driftdown (very rare). But if you have a cooperative dispatcher you may get more weight, but don't be surprised to see them want to add pax if possible.

 

[BoeingBoy]

Actually the scenario I painted is for very short flights which have an alternate required so that you are carrying more than usual fuel, but all of it is required.

Well, we fly some pretty short flights (or used to before the RJ's took them over) - CLT-CAE, CLT-GSO, CLT-GSP, CLT-AVL, with the shortest being 66nm. I suppose it's possible that a large area of bad weather would require a distant alternate with a corresponding large fuel requirement, which could make it problematic compensating for the J/S rider's weight. Just never seen it happen, but that doesn't mean it couldn't.

Our "pad" isn't as cut and dried - the amount varies as does the reason for it (possible deviations for WX & altitude changes for turbulance are common reasons.

Plus our dispatchers seem to be on the conservative side when it comes to fuel. Even with a program in place to cut down on extra arrival fuel (other than when tankering, obviously), it's extremely rare to land with anything even approaching minimum required fuel. In addition, it's rare (absent ground holds off the gate with the apu inop) to be within 500# of min T/O fuel when reaching the runway (not even counting all the times we tanker fuel).

Some of it may be aircraft configuration and routes operated on. With only 126/144 seats on the 300/400, there's less passenger/baggage weight than some carriers with a higher seating configuration. Plus we (US East) only fly the 737 in the eastern half of the country and Caribbean/Latin America - a long flight is 3 hours or so.

Obviously you have to land below MLW, but you can't takeoff at a weight that projects you to land above MLW according to the flight plan either.

Well, as you said above, the flight plan burn corrected for weight variance which is minor unless there's a big change in weight - about 150# per 1000# of weight change for a 3 hour flight. Probably less effect than a 2000' change of altitude. And while you're technically correct - you can't T/O knowing that you'll land above MLW - the flight plan is just a plan. It's not cast in stone. Our's are probably behind the times. They don't take into account T/O direction, landing direction, anything but uninterrupted climb (other than step climbs on long legs), etc. It's basically the old "measure with a micrometer, mark with chalk, cut with chainsaw" approach.

But if you have a cooperative dispatcher you may get more weight, but don't be surprised to see them want to add pax if possible.

We have something called a "weight capped" flight, which shows up on the release. It means the flight is expected to be within 500# of MTOW (usually due to MLW, but not always). If that's the case the maximum number of passengers is listed and I've only seen something other than maximum seating capacity once. That was when a MEL restriction plus tankering fuel reduced the allowable passenger count by 4 (which is what we were booked for when the release was prepared). So it's almost unheard of for a restriction to keep passengers off but still be able to get a jumpseater on. In addition, the jumpseaters usually ride in the back, so are included in the W&B as a passenger (or should be). If they're riding up front, there's probably not a seat in the back to allow putting more passengers on.

Of course, you've got to remember that all this is based on the 737 flying we do. Other airplanes may have more problems with weight restrictions, what limits weight, etc.

Jim

 

[john john]

Maximum ZFW is a structural limit - a "hard" limit if you like - and can't be wiggled out of. So if the airplane should be at that weight withoug the J/S rider, there's nothing that can be done (other than a couple of possibilities). Like I said, in 26 years I've never seen the maximum ZFW come into play - doesn't mean it couldn't, though.

Sorry again zero fuel weight is obviously the weight of the plane with out the fuel and my years of weight and balance ZFW has never been the controlling figure except with the new weights on the express A/C the dash-8 100 is routinely over ZFW