Hi, Thanks for your feedback and time.
When I see the trim sheets and even on flight plans the term "ZFW LMT TOGW" I wonder why it is called a limit?
I dont know if this term "ZFW LMT TOGW" is used universally or only in certain parts of the world, but getting a hint from what BOAC said:
Its just the way it has been done for years!
I assume that this term is probably used in many parts of the world.
If its not a limit in any sense then why call it a limit? I guess an expert on this subject knows it better.
I am clear on what its used for and have no issues with the trim calculations.
However I am just trying to find some explanation that might explain why it is called a limit.
The closest I could get was the following scenario:
Data
-----
Max TOW = 340
Max LDG = 250
Max ZFW = 237
Trip Fuel = 20 tons
Takeoff Fuel = 30 tons
Dry Opearating Weight = 200
Opearating Weight = 230
Calculations
-------------
Box A = 340
Box B = 270 (250+20)
Box C = 267 (237+30)
According to the terminology used in the trim sheets and flight plan (as discussed above):
Max TOW Limit = 267 (Box C)
Allowed Traffic Load = Box C (267) - Operating Weight (230) =
37 tons
Assuming an
actual tracffic load of 30 tons (i.e. an underload of 7 tons)
The
TOW = Operating Weight (230) + Traffic Load (30) =
260 tons
So:
TOW Box C Limit = 267
TOW = 260
If we want to increase the traffic load we can increase by up to 7 tons, considering Box C as a limit.
If we increase the traffic load by 8 tons then our TOW will be 268.
This means we have crossed our Box C Limit of 267.
This in turn means that we have crossed our Max ZFW Limit of 237 by 1 ton. (i.e. DOW (200) + Traffic Load (38) = 238)
However this is just my
assumption that may be because of this it is called "ZFW LMT TOGW".
Regards
