When should I start my Decent

[Tomcat61]

Can someone please give me some simple advice.

I am flying my 747, and I am on AP and cruising at 30,000Ft.

At what Nautical Miles from my destination should I commence my decent, and in what increments to allow for a nice smooth decent.

Thankyou.

[nitrotc3]

i suggest you fly IFR they will let you know when to descend but on vfr i think you should descend at about 30nm away from your destination at about 2000-3500fpm

[microlight]

Divide your flight level by 3 to give you the approximate distance from the target airport that you need to start a descent at 1800 fpm. For example if you are at 36,000 feet i.e. FL360, you'd start the descent at around 360/3 = 120 miles out. If you use the ATIS at the destination airport, this will tell you which landing runway is in action, and you can modify the descent accordingly.

Happy landings!  :)

[ysteinbuch]

You can also download add-on descent calculators. I don't have a link, but you can probably do a search at simviation's home page.

[BAW19]

I've posted this a couple of times before but it may be worth a re-post.
As soon as you start your descent you can easily calculate your vertical descent speed by multiplying your ground speed by 5. So if you're flying at 350kts (grounds speed) start your descent at 350*5=1750feet per min. As you get lower and you reduce your speed you should also reduce your vertical speed to maintain the descent slope. eg at 180kts you should be roughly descending at 800fpm. This rule gives you an ideal final approach speed of abouy 6 or 700 fpm. It will also make sure that if you use the 3x rule to decide when to start your descent you'll end up on the ground at the airport.
Once you get onto the ILS you may need to tweak your vspd to maintain the glideslope but it's only a rough rule.  
Good luck.

[ATI_7500]

good advices...gotta try it out.

[codered]

I usually begin my decent when ATC tells me, otherwise about 60 - 70 mile out if I am at high altitudes.  Desending at about 1500 to 2500 FPM.  However, I think all flights above 18,000 feet must be IFR.  Please correct me if I am wrong.  FS2002 doesn't model this, but if I remember right all flights in real life must be IFR above a certain altitude.

[microlight]

Thanks, Speedbird. I knew about the 'rule of three' but not about the 'rule of five'. Perhaps now I'll get down to 5,000 feet closer to the airport, rather than being there about 50 miles away!  :)

[PAUL PAN]

can anyone tell me how to use IFR ? when my aircraft is landing , no ifr tell me altitude , etc . how to use it ? paul

[S76pilot]

Here's a few methods....

1000 feet per minute......so if you are at 30,000 and the destination airport is at 1000 than you need to lose 29,000 feet and that takes 29 minutes to do

or

you need 3 miles for every thousand feet of altitude lost.  29,000 feet.....so at 87 miles back from the destination start down.

Here's a bonus   1/2 your ground speed x 10 will give you a nice gentle decent. 3 degree slope  

[BAW19]

Just a thought S76 - isn't half * speed * 10 = 5 * speed !!

Looks like we came up with the same rule  ;)

[Fly2e]

When should I start my Decent

When you run out of fuel!!!

[Deltawing]

[quote]I've posted this a couple of times before but it may be worth a re-post.
As soon as you start your descent you can easily calculate your vertical descent speed by multiplying your ground speed by 5. So if you're flying at 350kts (grounds speed) start your descent at 350*5=1750feet per min. As you get lower and you reduce your speed you should also reduce your vertical speed to maintain the descent slope. eg at 180kts you should be roughly descending at 800fpm. This rule gives you an ideal final approach speed of abouy 6 or 700 fpm. It will also make sure that if you use the 3x rule to decide when to start your descent you'll end up on the ground at the airport.
Once you get onto the ILS you may need to tweak your vspd to maintain the glideslope but it's only a rough rule.

[Fozzer]

When you run out of fuel!!!

Hi Fly...!

Less technical, but much more amusing... ...!

Decent = Descent... ...!

Cheers...
Paul.
(England).

[BE58D]

My suggestion is... To start your descent before you actually try and put it on the ground!