limitations

[niokilt 0]

Hi,

 

I guess this subject has been already discussed before, but I don't find any of it.

 

I don't understand why the values of MTOW that are listed on the payload page of the fmc of each versions of the bird (600,700,800,900) are so far from real values that we can get in the FCOM.

 

for example, the MTOW of the 800 shows 79.2 t but the FCOM indicates 70.5 t. with the 700 it is worst almost 10 t differences.

 

Thus, How can the flight model be accurate from a performance point of view, if the fmc is filled in with wrong values?

 

thanks

 

nic

[justinpilotatc 5]

I show the correct MTOW for the -800 in the FMC in pounds. I haven't checked the -7 or -9.

[scandinavian13 5,192]

I stole this from wikipedia because I didn't feel like explaining it myself:

 

"Among large airliners, the same model of aircraft can have more than one MTOW. An airline can choose to have its airliner certified for an increased weight at an additional cost. Some airlines which do not require a high MTOW choose to have a lower MTOW for that particular aircraft to reduce costs (Landing and air traffic control fees being MTOW based)."

http://en.wikipedia.org/wiki/Maximum_takeoff_weight

[KriVa 307]

Doing some more research would help out here, I think. Operators can choose to change their MTOW (for a fee), with some "tinkering".

So while two seemingly the same 738s might be standing next to another on the ramp, one could be certified for a 72T MTOW, while the other could have a 79T MTOW.

The FCOm of the first operator will say MTOW 72T, the FCOM of the second operator will show MTOW 79T.

 

EDIT: Drat, too late. Thanks, Kyle.

[scandinavian13 5,192]

 

 

So while two seemingly the same 738s might be standing next to another on the ramp, one could be certified for a 72T MTOW, while the other could have a 79T MTOW.

 

Very irritating, I'm sure, for the aircraft schedulers and dispatchers.

 

 

 

EDIT: Drat, too late. Thanks, Kyle.

 

Welcome.  I'm just sitting here with my head in the sand (a.k.a: forum) avoiding the OIS:

 

 

CTL ELEMENT: SFO
ELEMENT TYPE: APT
ADL TIME: 1706Z
DELAY ASSIGNMENT MODE: UDP
ARRIVALS ESTIMATED FOR: 25/1708Z - 26/0659Z
CUMULATIVE PROGRAM PERIOD: 25/1500Z - 26/0659Z
PROGRAM RATE: 27/27/27/27/27/27/27/30/30/30/30/30/30/30
FLT INCL: ALL CONTIGUOUS US DEP
DEP SCOPE: (MANUAL) ZAB ZSE ZFW ZKC ZME ZTL ZOA ZLC ZLA ZAU ZMP ZDV
ZID ZMA ZHU ZJX ZBW ZOB ZDC ZNY
ADDITIONAL DEP FACILITIES INCLUDED:
CANADIAN DEP ARPTS INCLUDED: CYEG CYVR CYYC CYYJ CYLW CYTZ CYYZ CYOW
CYUL CYQB CYHZ
DELAY ASSIGNMENT TABLE APPLIES TO: ZOA
MAXIMUM DELAY: 1447
AVERAGE DELAY: 183
IMPACTING CONDITION: WEATHER / LOW CEILINGS
COMMENTS: 

 

Yes, thats a max delay value of 1447 minutes at SFO.

 

*Pause for your mental math*

 

Yep, you're right: an entire day.

The average delay is only 3 hours at the moment, though.

[KriVa 307]

I'm not sure about other airlines, but the numbers for the 738 and 737 are the same fleet wide with us.

I know RYR doesn't handle the same principle, and often even changes numbers on a per-flight basis.

[scandinavian13 5,192]

 

 

I'm not sure about other airlines, but the numbers for the 738 and 737 are the same fleet wide with us.

 

You'd imagine...

 

Then again, we have airlines like Unitedental with IRU/IRU/DME 757s, mixed in with with the other 757s that Continental brought into the merger.  Nav equipment differences aren't the half of it.  Engine differences, and related weight differences (if only for the engines - not sure about altered maxes), and the current standing that only former COA pilots can fly COA metal...

 

Good luck schedulers!

[FLEX1978 373]

I'm not sure about other airlines, but the numbers for the 738 and 737 are the same fleet wide with us.

I know RYR doesn't handle the same principle, and often even changes numbers on a per-flight basis.

Was about to mention Ryanair & a few other airlines do indeed change the weight per flight to save on fees. Thinks its called Boeing Flex weight or something like that

 

Besides, if you look at the FCOM for an airline with a large fleet you will notice the DOW can vary quite a bit between aircraft of the same type.