Descent formulas

[Baronman]

The official XJT method, start down once you get the restriction, no matter what and annunciate, "ahh well...I'm just gonna start down now" ....Then, once you realize you're 40 miles out with 2 thousand to go, bleed it back to a 100fpm descent to make it look like you meant to do that ;-)

 

[flythere]

Somewhere, a 727 captain is rolling in his grave at the loss of the mental 3:1 descent planning calculation...

hopefully there will soon be some 60+ 737 capt's rolling over as well!!!

Dec 16th, 2012.......

 

[Salukipilot4590]

Fine, I'll give a serious reply this time:

From 280 to 180 = 10,000'

2,000FPM (F'k the damn fuel savings....this ain't the damn space shuttle)

10K @ 2000FPM = 5 minutes

What's our f'k'n groundspeed? 405KT?

405KT is how many miles per minute....6 something right?

WRONG!

ROUND DAT ISH UP! Its now 7 miles per minute (420KT....heh 420....is 7NM per minute brah)

...so now you have SIMPLE MATH....

5 minutes times 7 miles per minute =


COME ON SUSAN



35 miles.


Since you're not going to want to throw -2000FPM into the AP controller and throw Dave's coffee into Becky's chest region you're going to add 5NM to that for a lead in and lead out....



So.....



Now you've got 40 miles...plus or minus whatever the cap'n wants to add since he's doubting your abilities as a competent pilot....you damn kids.

 

[Uncle Bunkle]

Pull thrust to idle and pop the speed brakes, works every time.

 

[Pogue Mahone]

Four pages....only on Flight Info.

 

[xjhawk]

VNAV Baby But yah, take the number of feet to lose times it by 3

At FL Level 350 / Cross X Fit At 15,000 feet = 20,000 feet to descent (20 x 3 = 60), Also, you might want to add 10 miles for the initial pitch down and level off delay. Than, take the GS and divide it by 2. So 500 KIAS / 2 = 250 (add a 0) = 2500 FPM.

A long time ago I was told to add 10 miles to the 3:1 rule when you are going below 10,000 for the slow down. If I am not mistaken V nav does not take that into account. Nor does it take into account the short legs where it never seems to cool down in the CRJ so when full I never do idle decent and like to keep some air going back there. Below 10 I then start the APU for the slam dunk I can expect at half the places we fly. If I hear that future interviews will be a bunch of unrealistic math problems involving two trains and a collision I will be sorely disappointed. Is there truth to the rumor that Delta asks a question that goes something like this....."if on approach at speed 250 and are told there is an A/C in front of you going 210, how long before you over take it?" My answer will always be "never, I will slow down before that happens."