Planning a descent

[Jimjetter]

Hi

Another quick question....

When say planning a descent "to be level by a certain point" whats the quick way of working out how many miles before to start the descent...?

Sure there was a way involving speed and how many thousands of feet you needed to descend...

Thanks

[JB007]

Based on a constant ROD of 1500 fpm, the required altitude loss (divided by 1000) multiplied by 3 to obtain the distance from the bottom of descent point at which descent should be commenced!

Hope that makes sense - sounds more complicated than it is!

I prefer minutes to go = present altitude @ 1000 fpm!

Cheers
JB

[moggiee]

It does rather depend upon groundspeed and rate of descent.

However, most airliners manage an average of 1000' of descent for every 3 nm travelled.

[Bluebaron]

or just tap in the FMC and see what it said!!

BB

[Piltdown Man]

Three times table, ish...

You have to loose nine thousand feet - therefore three times nine equals 27 miles. Groundspeed 400 kts, ROD required equals 2000 fpm or so. Apparently this is OK unless you are flying an A330, which requires the four times table.

Unless of couse you have an FMS when your tap in your request and it does the rest (or heaven forbid, you use V/S and use the BOD arc on the ND.

Flying jets etc.. is not rocket science (you might say it's jet science). They are designed to be flown by plonkers (and there are many of them out there, myself included) on bad night.



PS: If you then have to loose speed, more distance has to be added

[Bernd Podhradsky]

Hi!

or just tap in the FMC and see what it said!!

Before I do that, I let my co-pilot do it manually without any technical equipment .

Bye,
Bernd