Aircraft range (was Re: Why "IGW" instead of "ER", and other question about 777's...)

Date:         30 Apr 97 03:19:08 
From:         "Alvin W. Law" <alaw@us.oracle.com>
Organization: Oracle Corporation, Redwood Shores, California
References:   1 2 3 4
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M Carling wrote:
>
> tassio@watson.ibm.com wrote:
> >    According to Boeing's web page, the range for the heaviest 777-300
> > is 6500mi, and the 747-400 range is 8290mi. I imagine the range for a
> > 777-300X will be about the same as the 747-400. Given the 777's much
> > lower operating costs, what would then be the advantage of
> > operating the 747-400 (as opposed to the 777-300X)?
>
> While Boeing's web page claims 8290 miles for the 747-400, this is
> wildly optimistic. The longest non-stop route that anyone has been able
> to fly in both directions is United's ORD-HKG service at 7786 miles,
> which can only be flown during the summer, and is severely
> weight-restricted (301 seat configuration versus the usual 420 seats,
> and no cargo).
>
> On the other hand, Boeing's claim of 8225 miles for the 777-200IGW
> appears to be very conservative. I believe it is Boeing's official
> policy that the 747-400 has greater range than the 777-200IGW, though
> the evidence seems to suggest that the 777-200IGW has a range of at
> least 500 miles more than the 747-400.

Pardon my ignorance here but I have a question regarding aircraft ranges
as published by airframe manufacturers for promotional purposes.  As many
of the so-called ultra-long haul routes are trans-Pacific which are heavily
affected by the strong westerly wind, what kind of guidelines are the
airframe manufacturers using to calculate the maximum range?  Here are
some of the permutations I can think of:

- full loaded pax vs. fully loaded pax and cargo
- uni-directional vs. bi-directional
- w/ head / tail wind vs. w/o head / tail wind

I've flown on fully loaded 747-400s for 15+ hours non-stop.  Assuming no
head winds, a range of 8,000+ miles is certainly achievable, at least
theoretically.  And while the longest bi-directional non-stop 747-400
route is ORG-HKG at 7786 miles as stated, it is limited by the westbound
segment.  The eastbound flight (HKG-ORD) certainly is capable of handling
a larger payload or a longer range during summer, and even more so during
winter.  I think a 747-400 can quite possible handle HKG-JFK with a full
load during winter months.