Assuming a still air situation (no headwind or gust factor required):
The Boeing FCTM guidance on touchdown speed is often sadly overlooked in favour of one to one instructor's technique. When Pilot Monitoring I see the majority of touchdowns occurring at the nominated approach speed (Vref+5 in still air) which is 5 to 10 knots too fast. This is usually due to nervousness that stems from that old fable of "it falls out of the sky if you go below Vref." A very small reduction of thrust (3% N1 depending on landing mass usually works for me) just prior to the 50 feet point will allow crossing of the screen height at Vref; that thrust setting can then remain unadjusted until the end of the flare (ie nose raised to a suitable touchdown pitch angle) at which point thrust is immediately reduced to flight idle allowing wheels to contact at Vref-0 to Vref-5, as BOAC correctly defines.
To nail these speeds proficiently requires some discipline in the PF to constantly check the speed tape against the outside visual picture in the last 100 feet and make tiny adjustments to thrust.
Has anyone been taught the novice's technique of.....
For Flaps 30: CHECK and CHOP (check the nose attitude is raised, then chop the thrust levers to idle)
For Flaps 40: CHOP and CHECK (chop the thrust levers, then raise the nose attitude)
....this worked as a good starting method for me when new to type. I think the different method for Flaps 40 stems from a greater air cushioning effect produced by the flaps allowing more time to place the aeroplane on the runway, but I'm no aerodynamicist.
In fact, I don't even know if aerodynamicist is a word.
For a different can of worms, I never cease to be horrified by that cancer of a technique that thrust is used to correct for glideslope. Why do so many medium jet trainers get away with teaching that???
Last edited by Kiltie; 8th Jun 2010 at 12:56.