View Full Version : Differing a/c cruise speeds - what are the knock on effects?
I'm sure this one has been done before on PPrune, but couldn't narrow a search down well enough, and given the new A380 (see various current threads), thought it might make for some (re-newed) interesting discussion.
So:
- Does the A340 continue to get in the way of faster aircraft (eg B744) during cruise ?
- Any other aircraft that are fast or slow ? (Eg B767?)
- What about the A330, which is now being used regularly on many long haul missions ?
- What will be the cruise speed for the A380 ?
- Will the A380 also be a slow mover in the fast lane ?
- Does it matter ? Does it affect you ? If so, how & how much ?
Any comment from pilots or ATCO's ?
Many thanks
Z.
Always. And don't believe the rubbish Airbus publish about it being a .82 cruise aircraft
static
9th Jan 2001, 18:33
A340`s are always in the way, as are 767`s.
Over Siberia, they even have their own airways! (three cheers for the Russians).
What it costs? In practice you settle for an off optimum level. For the 744, this means 4000 ft lower and an increase of approx. 4% in fuel consumption.
Kerosene Kraut
9th Jan 2001, 18:55
Avweek of January 1st reports that the A380-100 will cruise (long range) at M 0.85. That's just like a 747-400. The 747X Stretch is said to be cruising at M 0.86.
160to4DME
9th Jan 2001, 22:55
At the other end of the scale, one colleague lost seperation with a 734 on a SID followed by a Saab 2000, 2 minutes behind. Both had to level off at the SID altitude due other traffic.
Radar recordings showed neither broke the speed limit, yet the Saab accelerated to 250kts far quicker than the 73, and seperation was lost, degrading to 2.2 miles before becoming constant.
Bloody fast those Saab Screws :)
Buckshot
10th Jan 2001, 03:10
Airbus claims a cruise speed for the A380 of M0.85 with flexibility to operate up to M0.88.
They also claim to be able to reach initial cruise altitude FL330 in 30 minutes at MTOW of 1,285,000 lbs. Yeah right.....
B767,A340,A330,A300 and occasionally the B777 are always getting in the way of 747s.
The same problems happen every day. A B767 (M.78) in the lead followed by a A340 (M.82) then a B777 (M.84) then a B744 (M.86). My question is:- Is any thought given to enroute separation requirements when scheduling. Pilots often complain when they can't get their level but if they left 10mins earlier or later it may relieve the problems most of the time?
Spodman
12th Jan 2001, 04:53
Not to mention B747 getting in the way of B747. Different companies fly 'em at different speeds out here.
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I am not an animal, I am an ATC.
DoctorA300
16th Jan 2001, 05:54
Seems to me that it is not the A330,A340,B767
or the B777 that are in the way, but the B747 that are speeding http://www.pprune.org/ubb/NonCGI/tongue.gif