Re: 747-400 Initial Cruise

Date:         22 Nov 97 20:41:23 
From:         mweber@t140.aone.net.au (James Matthew Weber)
Organization: Customer of Access One Pty Ltd, Melbourne, Australia
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On 21 Nov 97 01:59:53 , "Bart & Sylvia Peters"
<bapeters@worldonline.nl> wrote:

>>BTW, can someone post "normal" cruising altitudes and speeds for the
>>main types used today?
>
>For a Boeing 747-400 initial cruise altitude at max t/o weight ( most of the
>time ex- far-east ) is FL 310 mach 0.85 depending on actual wind at the
>time.
>After Delhi a climb to FL 350 and mach 0.86 are possible.

I don't believe this.

Cruise on a 747-400 at these mach numbers carries a huge fuel burn
penalty. There is now ay the aircraft would make a Europe-Asia trip at
those speeds. Long Haul Cruise on a 747-400 is M.82, while M.86 may be
possible, I have never seen anyone do it.

  Have anyone out there seen it?

My own experience with a RR powered 747-200 is a throttle push from
M.82 to M.84 cost 20,000 pounds of fuel on a 9.5 hour flight. That is
about a 10% penalty.

I've been in a D10 at m.85 (ATC kept asking us to go faster), when he
asked again, the boss said, hey, we already doing M.85, I can't go
much faster. The response from ATC was, OK, at least don't slow down
for a while.

777's are often found at M.85, that is where they were designed to
Cruise (it was an interesting way to attack the A340. On very long
flight the difference in cruise speed has a very real impact on travel
time).