I'm a tad confused:
Vref speed (landing speed) for a given weight is the same if at sea level or high elevation, in all airplanes... There is no altitude consideration in the Vref tables - only a weight consideration...
whereas Rick767 wrote:
Vr speeds (IAS) are higher at high pressure altitude / high temperature airports. We have a chart with the relevant corrections.
Assuming that Rick meant reference speed (and not Rotation Speed) when he wrote "Vr", only one of the above can be true, unless there are different operating procedures for the B767 and B747 that I'm not aware of.
Fom an analytical standpoint, here's how I see it:
For a given aircraft weight, maintaining the same approach profile at AMS
and LPB with more or less the same thrust setting requires the lift and drag forces during approach to be more or less the same.
The lift and drag forces are functions of True Air-Speed (actually TAS-squared), not IAS.
Lift Force L = 0.5 * CL * Density * TAS ^2 * Wing_Area
Drag Force D = 0.5 * CD * Density * TAS ^2 * Wing_Area
are the lift and drag coefficients (primarily functions of angle of attack and flap angle) CD
is also affected by the wing aspect ratio (induced drag)
The density at LPB (13,700 MSL) is quite a bit lower than at AMS
To maintain more or less the same final approach profile at AMS
and LPB, you would need a higher TAS at LPB than at AMS
Now, if B747Skipper is right, and you had a B744 on finals at LPB doing 152 KIAS, the true-airspeed would be around 190 KTAS (I'm assuming the 2% per 1000 ft density altitude rule of thumb) which is higher than the ~152 KTAS you would get at AMS
The question then is whether this ~25% increase in TAS is regarded as sufficient to offset the decrease in density at LPB. It also depends on the degree of flaps used which affects CL
and as I alluded to earlier, on the thrust setting on finals.
I suspect that this whole discussion is largely academic, because I dont see a carrier planning operations with a B744 @ anything close to MLW to LPB anytime soon!
I'd love to get some feedback on my $0.02 worth.