Re: 747-400 Initial Cruise

Date:         29 Nov 97 03:24:32 
From:         "Michael F. Lechnar" <michael.f.lechnar@boeing.com>
Organization: nams
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James Matthew Weber wrote:
> 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.

Nope,

Long range cruise Mach, LRC, for the Pratt & GE 747-400s is between .85
and .86 Mach.  Rolls is a touch slower.  The only reason you would be at
.82 Mach is to fly max range cruise at lower weights or for ATC.

I have seen Mach .86 a lot.

Mike Lechnar
Aircraft Performance Engineer
"If I was speaking for Boeing, I wouldn't be doing it here."