Calculating speeds, rates and times

[Olendirk]

Guys,

how to calculate a descendrate that i have to fly to reach a fix in XX minutes from a flightlevel at an altitude? For example, from 410 be at level in 300 in 7 min?How to get the gnd speed with easy formulas? What else formulars can be useful for flying a 737?

Thanks so much!


OD

[asuweb]

Wish I had an FMS.

[hetfield]

1. R.O.D. = 5 x GS

2. Top of Descent at = ETA minus 30 min

3. Amount of Extra Fuel = 1 line of Forecast equals 1.000 kg, 2 lines of Forecast e. 2.000 kg

[AirRabbit]

Another reasonably good "rule of thumb" is:
Mach Number = Nautical Miles per minute.
e.g., M=0.75 or about 7.5 Nautical miles per minute

[PAPI-74]

Alt to loose x 3
then add 10 for slowing down

11000' (11) x 3 = 33

add 10

at 1500 fpm your TOD is 43 NM from way piont.

[Capn Bloggs]

410 be at level in 300 in 7 min

410-300 = 11,000. Divide that by 7 and there's your required rate of descent answer...