descent plan
Join Date: Sep 2002
Location: Calgary, Canada
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On the B737-200 the following works like a charm can't speak for other types:
M.70/280 Kts use the 3 times your altitude rule to calculate a distance to descend.
M.72/300 Kts use 2.5 times altitude
M.74/320 Kts use 2 times altitude
For deceleration from descent speed to 250 Kts @ 10,000 ft reduce decsent rate to 1000 FPM passing 12,000 ft and you will be slowed a little early if doing a 280 descent and just right if doing a 320 descent.
Add 10 miles to descent distance for deceleration.
Using 430 Kts as a zero wind groundspeed for every 10 Kts of head/tailwind adjust distance by 2 NM. For tailwinds add the correction for headwinds subtract.
Example:
Descent from FL330 to 4000 ft, G/S = 490 Kts, planning a 3:1 profile and deceleration to 250 Kts @ 10,000ft.
Alt change = 29,000ft
Tailwind comp = 60 Kts
Alt change (29) X Profile ratio (3) = 87NM
87 NM + tailwind correction (12) = 99 NM
99 NM + deceleration distance (10) = 109 NM
Try it, it has worked for me for the last number of years. Be sure to crosscheck every 2-3000 ft (every 1000 ft is better) and adjust the profile as necessary for changing winds on the descent. Correct your profile early (higher up) for better efficency.
Also remember that a lighter A/C (below 95,000 lbs) will descend faster than a heavier one. Yeah I know initially it defies logic initially but think inertia.
Good Luck
Cheers
M.70/280 Kts use the 3 times your altitude rule to calculate a distance to descend.
M.72/300 Kts use 2.5 times altitude
M.74/320 Kts use 2 times altitude
For deceleration from descent speed to 250 Kts @ 10,000 ft reduce decsent rate to 1000 FPM passing 12,000 ft and you will be slowed a little early if doing a 280 descent and just right if doing a 320 descent.
Add 10 miles to descent distance for deceleration.
Using 430 Kts as a zero wind groundspeed for every 10 Kts of head/tailwind adjust distance by 2 NM. For tailwinds add the correction for headwinds subtract.
Example:
Descent from FL330 to 4000 ft, G/S = 490 Kts, planning a 3:1 profile and deceleration to 250 Kts @ 10,000ft.
Alt change = 29,000ft
Tailwind comp = 60 Kts
Alt change (29) X Profile ratio (3) = 87NM
87 NM + tailwind correction (12) = 99 NM
99 NM + deceleration distance (10) = 109 NM
Try it, it has worked for me for the last number of years. Be sure to crosscheck every 2-3000 ft (every 1000 ft is better) and adjust the profile as necessary for changing winds on the descent. Correct your profile early (higher up) for better efficency.
Also remember that a lighter A/C (below 95,000 lbs) will descend faster than a heavier one. Yeah I know initially it defies logic initially but think inertia.
Good Luck
Cheers
Keep it simple.
3 x ht (ie 30,000ft = 90 miles)
Make an allowance for headwind/tailwind and engine anti-ice if
being used ( higher idle setting)
Use 'gates' on the way down. Approx 16000 at 50 miles - 10000 at 30 miles works for me.
Small corrections to profile made early prevent large deviations
in either direction.
Practice makes perfect
Good Luck
3 x ht (ie 30,000ft = 90 miles)
Make an allowance for headwind/tailwind and engine anti-ice if
being used ( higher idle setting)
Use 'gates' on the way down. Approx 16000 at 50 miles - 10000 at 30 miles works for me.
Small corrections to profile made early prevent large deviations
in either direction.
Practice makes perfect
Good Luck
Join Date: Oct 2001
Location: Neverhome
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For standard ECON descent in B744: (current Mach into 290):
(3 * Height + x ) +/- 1/3 of H/W or T/W component.
(where x decreases from 20 at FL400 to 10 at 10,000')
Eg: From FL400 with 60kt H/W: (3 * 40) + 20 - 20 = 120NM
From FL300 with 30kt T/W: (3 * 30) + 20 + 10 = 120NM
You can obviously interpolate for other altitudes (eg FL350) and these are only ballpark figures but once you get a bit lower use:
20,000': 80nm (Hard Gate)
10,000': 40nm (Hard Gate)
5,000': 20nm 250KTS (Hard Gate)
LH
(3 * Height + x ) +/- 1/3 of H/W or T/W component.
(where x decreases from 20 at FL400 to 10 at 10,000')
Eg: From FL400 with 60kt H/W: (3 * 40) + 20 - 20 = 120NM
From FL300 with 30kt T/W: (3 * 30) + 20 + 10 = 120NM
You can obviously interpolate for other altitudes (eg FL350) and these are only ballpark figures but once you get a bit lower use:
20,000': 80nm (Hard Gate)
10,000': 40nm (Hard Gate)
5,000': 20nm 250KTS (Hard Gate)
LH
Join Date: Mar 2000
Location: Arizona USA
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One airline that I worked for suggested...
On descent plan on the following,
FL300.....at 90nm
FL200 at 60nm
FL 150 at 45nm
FL100 at 30 nm, slowing to 250 KIAS
If the airfield is well above sea level, adjust accordingly. Worked for them, especially for the newer guys under training.
On descent plan on the following,
FL300.....at 90nm
FL200 at 60nm
FL 150 at 45nm
FL100 at 30 nm, slowing to 250 KIAS
If the airfield is well above sea level, adjust accordingly. Worked for them, especially for the newer guys under training.
