|
It is currently Sat Apr 20, 2024 3:00 am
|
View unanswered posts | View active topics
|
|
|
|
71-1091752782
|
Post subject: Posted: Sun Sep 11, 2005 4:19 pm |
|
Yup, the easiest rule of thumb (and the one I use) is to simply triple the altitude you have to lose.
But then you have to know how fast to decend....
Try taking your groundspeed, divide by 2, then add a zero.
e.g. 250kts/2 = 125, add a zero = 1250fpm descent rate.
This way, you won't be leveled off while still 30 miles from the airport and trying to figure out what went wrong
Darryl: That's exactly what's done in the "real world" ... Take your groundspeed and convert that to nm/min. Then figure out a time to descend based on a known rate of descent. Multiply your G/S (in nm/min) by the time to descend and the product is your TOD.
e.g. Flying 240kts G/S = 4 miles/min. We want to descend at 1500fpm and we have to lose, say, 10,000 feet. So.... 10,000 feet at 1500fpm = 6.6666666666666666666 minutes. At 4 miles/min, that's approx 26.7 nm (6.67*4). Pull the power back at 27nm, keep the VSI pinned at 1500fpm and you'll look like a star!
To add a level of preciseness, calculate your TOD from the point at which you will be commencing the approach: Remember that it could be 20 miles on "this" side of the airport, or 20 on the "other" side.
Oops: I'm getting a little off-topic from "rules of thumb" ... Doh!
Cheers!
Gary
Edited By Gary Madore on 1126456932
|
|
|
|
|
|
|
|
|
|
|
You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum
|
|