Originally Posted by
extricate
Thanks. Any reference material for the 5kts per 0.01M ?
Just bung the basics into a CRP computer .... or some of the great apps that are available and you'll be able to prove it to yourself. Some people might argue a knot or so either way but that's close enough for government work - especially at 2am 20 hours into a 30 hour day.
Alternatively, in the cruise disconnect the autothrust and see for yourself i.e click back the mach knob and look at the IAS change ........ if your airline allows you to touch the thrust levers :-)
The example you mention is also great when ATC says cross x at time Y. If the FIR etc is, say, 2 hours away and you need to lose, say, four minutes - can you reduce that much ? Well 5kts per 0.01 - does it keep you above minimum? then how much do you need to reduce without spending 10 minutes in the FMC? - Well 1 min per 0.01 per hour .... so just knock the speed back 0.02. Answer to ATC as he finishes the question !
There are also some great aviation "rule of thumb" sites out there with some real gems - all from the steam driven days of aviation but they still work.
My favourite was, the TAT at 18,000 feet equals the ISA deviation at top of climb ...... a real help in the old days for heavy widebodies (I also proved that one too from the equations but don't ask me to find it)
Cheers