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Archive => Other Topics => Old Forum => Flight Simulation => Topic started by: EHM-1464 Andrew on August 03, 2004, 12:19:52 am

Title: planning your decent :s
Post by: EHM-1464 Andrew on August 03, 2004, 12:19:52 am: ive been coming in really high into airports recently, like 10,000ft to high and end up circling round loads to loose altitude.. its obvious im starting the decent too late..

what im wondering is what techniques you use for planning your decent and making sure your at the right altitude at the right time!
Title: planning your decent :s
Post by: EHM-0962 Zhen Yi on August 03, 2004, 06:48:21 am: The distance for descend depends on your plane and altitude.....if you're flying a 747 it's best to start descending 200nm away so that you dont have to dive down when nearing the airport.....for class one planes though 20nm should be more than enough

I'll suggest using your throttle and maybe a bit of flaps to help mantain your altitude but watch out for the speed at the same time! ;)
Title: planning your decent :s
Post by: EHM-0005 Maarten on August 03, 2004, 10:26:00 am: Formula:

A = Ground Speed
B = Descent (the altititude you want to 'lose' in feet)
C = Track (NM to the airport)
D = Vertical Speed

D = B / ((C/A) * 60
Title: planning your decent :s
Post by: EHM-1464 Andrew on August 03, 2004, 11:55:27 am: execellent maarten.. am i right in thinking that should have another bracket on the end?.. thats just what i wanted..
Title: planning your decent :s
Post by: EHM-1365 Benjamin on August 03, 2004, 04:25:10 pm: Wow....that is a really good way of working it out...nice one!;)
Title: planning your decent :s
Post by: EHM-1077 Emanuele on August 03, 2004, 08:38:21 pm: There's also a rule of thumb: 3-4 nm for each
1000ft of descent, plus 5nm.
I.e. if you want to go from 31000ft to 5000ft:
(31 - 5) * 4 + 5 = 109 nm.

But Maarten's formula is much nicer. =)

Ciao ciao!

Manu
Title: planning your decent :s
Post by: EHM-0962 Zhen Yi on August 04, 2004, 08:26:00 am: Looks like i over estimated the distance for descend for the big jets :P also please remember to keep the descend shallow when applying the formula
Title: planning your decent :s
Post by: EHM-1464 Andrew on August 04, 2004, 03:35:58 pm: also remember you are wanting to be at 3000ft 10nm before the airport.. not over it..

im still working on my descents.. and they are imroving..

does anybody have any more formulas for calculating flights/parts of flights?..
Title: planning your decent :s
Post by: EHM-0813 Guillermo on August 07, 2004, 09:30:45 pm: Quote
Originally posted by andycb
ive been coming in really high into airports recently, like 10,000ft to high and end up circling round loads to loose altitude.. its obvious im starting the decent too late..

what im wondering is what techniques you use for planning your decent and making sure your at the right altitude at the right time!

Remember not to decend with -1800fpm at high speeds, this is too slow. -2500fpm is nothing uncommon, we even decended -4850fpm in the 744, though this was only for a minute or so.
Title: planning your decent :s
Post by: EHM-1383 Syed on August 22, 2004, 09:31:09 pm: Use Visual Approach Slope Indicators (VASI) / Precision Approach Path Indicator Lights (PAPI). :)

But you can't always rely on them though. Sometimes you can't see them due to poor visibility and also not all runways have those. In the first case you make an ILS landing and In the second case you should do the things said earlier in this topic. ;)

Check this out:-

PAPI/VASI Tutorial:
http://www.fs2004.com/forums/index.php?showtopic=19071

ILS Landing Tutorial:
http://www.fs2004.com/forums/index.php?showtopic=1959
Title: planning your decent :s
Post by: EHM-0962 Zhen Yi on August 23, 2004, 10:28:00 am: Really awesome and detailed guide! Thanks for posting the link! ;D