|Quoting b747400erf (Reply 22):|
I have been following the 3 (now 4) 77W's from Swiss and using their cruise altitudes, calculated around what their zero fuel weights have been. And they are very light. If filling up a 77W with 30.000 kgs less than max weight is successful, even on what should be a big route for pax and cargo to HKG, then the 77W is too much plane for you. Little cargo loads on all of their flights.
I just gave LX138 ZRH
a look, and the final step climb on most days is FL350. On the days where they do reach FL370, it is typically for 1h-1h30m. Doing some backwards calculations you are looking at ZFW ranges of 215-230t.
Nowhere near 30t below MZFW. MZFW of course being 237t on the -300ER
In addition, you do not consider the vast DOW range between different operators aircraft. A certain Taiwan based B77W operator has DOW's (Crew + bags + water + pantry TPE
-USA) averaging ~173t. The worlds largest B77W operator, with a configuration seating only 4 seats less (in its ULR configuration), has a DOW range between ~177t and ~179t.
At a constant ZFW of 230t, the Taiwan based B77W operator would be carrying 4-7t additional payload.
Going back to the LX138 ZRH
example, using 11h30m as the average flight time (wheels up, wheels down) you are looking at 110t-112t of Release fuel (including: trip, alternate, contingency, final reserve, taxi). As far back at FR24 allows, they are all going to FL310 initial. Based on the latest Boeing B777-300ER FPPM, at 340t, MAX is FL316 (1.30 margin). Hence their initial FL310.
Assuming: 340t ATOW, 112t release fuel, you get 228t ZFW. Which explains FL350 as the final step climb on most days. On days where they load 7-8t less payload, they manage FL370.
If indeed they were departing 30t below MZFW (using this route as a example), they would be going to FL330 initial, every single day.
In summary, numbers dont lie, and your assessment of the payloads carried on LX138 ZRH
, is way off!
I would also like to point out something else. The LH
group has never been known to waste money on purchasing MTOW options that they do not make use of. This is precisely why their B744s were never purchased with the highest MTOW option offered by Boeing. There is no point in having overflight and landing fees assed on a higher weight if you'll never be making use of it. After Boeing increased the B748 MTOW and the first few LH
frames were delivered with the slightly lower initial MTOW, LH
still decided to take the remaining ones at the same and lower MTOW.
's B77Ws are 351,543kgs MTOW for a reason. The highest MTOW offered by Boeing, and of course the most expensive of the various MTOW's you can purchase on the B77W.
In comparison: SU
operate their fleet at 317t MTOW. The lowest MTOW anyone has purchased on the B77W. Little demand for belly freight and hence also the small aft cargo door option.
ZFW: (Zero Fuel Weight)
MZFW: (Maximum Zero Fuel Weight)
ATOW: (Actual Takeoff Weight)
FPPM: (Flight Planning and Performance Manual)
DOW: (Dry Operating Weight)
[Edited 2016-06-07 11:36:54]