Re: B777-300/B777-300ER???

Date:         17 Jan 99 02:37:22 
From:         James Matthew Weber <jmweber@goodnet.com>
References:   1 2
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>Note that IGW does not necessarily mean that there is more fuel capacity
>nor that the maximal range is augmented over the base model. Higher
>weights can just mean that you get a more favourable trade off between
>payload restrictions applying and fuel quantity required when you're
>flying on route segments approaching the range/payload limits of the
>aircraft. No aircraft goes the maximum range with maximal load, as you
>would for sure exceed the MTOW (Maximum Take Off Weight) and thus
>compromise operating safety when you try to do so (ok, some guys tried
>before, and not all got away with it, but that's a different story).

I am going to take issue with that statement. If you look at the 777-200
base versus the 200IGW/ER model, there is a very large difference in
available MGTOW. 777-200 has an MGTOW is 545,5000 pounds. The IGW/ER is
now available up to 648,000 pounds.

However a much interesting figure is Maximum Landing Weight, or MLW. The
777-200 MLW is 445,000 pounds. Early -200IGW/ER's were also 445,000
pounds, although that has subsequently been increased to 460,000 pounds.
Even then there was an increase in empty weight of about 3000 pounds
between the -200 and the IGW/ER variant.  If the MGTOW goes up and
landing weight doesn't, the only thing the extra MGTOW can be used for
is fuel carriage. If the only thing you can use the extra MGTOW for is
fuel carriage, how can it not be for extra fuel carriage?

Until the sector length is such that the fuel burn exceeds the spread
between MLW and MGTOW, some versions of the IGW/ER aircraft will
actually have less lift capacity than the standard 200. (Higher empty
weight, and same landing weight as standard -200).

James Matthew Weber  1 602 315 6520   Fax 1 602 638 1316
Gulf Computers Inc.