TOD Calculations??
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TOD Calculations??
I can vaguely remember from training that there is a some quick way of working this out, but I can't seem to recall it.
Something to do with height in feet x4 +10 to slow down, gives distance in NMs to commence descent. Renewing my IR soon so this would be helful, any info greatly appreciated!
Cheers
CP
Something to do with height in feet x4 +10 to slow down, gives distance in NMs to commence descent. Renewing my IR soon so this would be helful, any info greatly appreciated!
Cheers
CP
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erm, nearly i think its 3 x height + 10 to slow down.
e.g. FL330 = > 33,000ft
=> 33 x 3 = call it 100 + 10 = 110 nm.
I assume that if you have intermediate levels you could times the difference by 3 and still get a sensible figure.
e.g. FL330 = > 33,000ft
=> 33 x 3 = call it 100 + 10 = 110 nm.
I assume that if you have intermediate levels you could times the difference by 3 and still get a sensible figure.
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TOD etc
For your unpressurised ac, which I assume you will renew your IR in, the x4 rule + d is fine, with a say 700 fpm ROD, with a max of 1000 fpm.
The x3 rule is really for pressurised ac.
The x3 rule is really for pressurised ac.
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For an unpressurized aircraft, I have been told:
Loss of altitude divided by 2 (as for 2° descent path)
Exemple: you want to leave FL070 down to 2500' (forget about pressure altitude/altitude difference here).
70 - 25 = 45 and 45 / 2 = 22.5 = 23 NM
That will give you, for a 150 kt Ground Speed, a 500 fpm rate of descent. [(150/60) x 2]
As 700 fpm is the maximum recommended for passenger confort and health, a 210 kt Ground Speed descent should be the maximum usable for an unpressurized aircraft.
FLEXJET
Loss of altitude divided by 2 (as for 2° descent path)
Exemple: you want to leave FL070 down to 2500' (forget about pressure altitude/altitude difference here).
70 - 25 = 45 and 45 / 2 = 22.5 = 23 NM
That will give you, for a 150 kt Ground Speed, a 500 fpm rate of descent. [(150/60) x 2]
As 700 fpm is the maximum recommended for passenger confort and health, a 210 kt Ground Speed descent should be the maximum usable for an unpressurized aircraft.
FLEXJET
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Number rule;
120kt (ground speed) = 4nm @ 500ft/min
150kt = 5nm
180kt = 6nm
and so on...........
The way it works (unpressurised A/C) take you alt ie 9000ft then multiply it by that GS figure above and you will get your TOD.
example: your at 9000ft doing 180kt GS what is your TOD?
9000 = 9
180 = 6
9x6=54 (TOD is at 54nm)
Nice and easy, good luck for your renewal
120kt (ground speed) = 4nm @ 500ft/min
150kt = 5nm
180kt = 6nm
and so on...........
The way it works (unpressurised A/C) take you alt ie 9000ft then multiply it by that GS figure above and you will get your TOD.
example: your at 9000ft doing 180kt GS what is your TOD?
9000 = 9
180 = 6
9x6=54 (TOD is at 54nm)
Nice and easy, good luck for your renewal
I'matightbastard
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I just subtract 1500' from the cruise altitude - which fortunately is always VFR - and multiply by six
The reason is that all the airports I use are at about 500' and I'm doing about 180 kts and I'm looking for a 500fpm descent (not that I can ever hold that mind)
The reason is that all the airports I use are at about 500' and I'm doing about 180 kts and I'm looking for a 500fpm descent (not that I can ever hold that mind)
