Welcome to JamiesAviation.com - a showcase project demonstrating the Wizardry of KryptonScientific!
C O N T E N T S

Home

In the press

World Aerodrome Data
Global Weather

E6BJA (E6B) Flight Computer

Photo Galleries
Articles and Docs

Air Warriors

 Jamie's Online Flight Calculator
Jamie's Aviation Flight Computer

Now available as an Android app on the Google Play Store

Top of Descent calculator

Top Altitude: ft
Bottom Altitude: ft
Glidepath (slope): °
Offset: NM
 
Start Descent: NM


Rate of Descent calculator

True Airspeed: kts
Glidepath (slope): °
Course: °
Wind Direction: °
Wind Speed: kts
 
Rate of Descent: (ft/min)
Ground speed:
Wind Correction Angle: °
Fly Heading: °

How Top of Descent is computed

The difference in height between the top and bottom altitudes given is used along with the Slope angle to compute the run (distance) from which to start the descent, i.e. the Top of Descent distance. Any offset given (>0) is also added, for instance when it is desired to be at the bottom of descent at this offset from the destination.

Quick rule-of-thumb for mentally calculating Top of Descent for a standard 3° glidepath slope

The Top of Descent can be roughly approximated by a general quick rule-of-thumb:

(Difference in Height/1000) x 3
NB: This rule-of-thumb only works for a 3° glidepath (standard slope).

How Descent Rate is computed

The computer firstly uses the Wind Correction Angle (WCA) to calculate the Ground Speed (GS). Secondly, the Ground Speed is adjusted accordingly for the wind i.e. subtracting any headwind or adding any tailwind. Thirdly, the revised Ground Speed and the Slope are used to determine the Rate of Descent. Finally, the Rate of Descent (given in ft/min, fpm) is calculated from the tangent of the slope and the True Airspeed. The Wind Correction Angle (WCA) and resultant heading to fly are also given for convenience.

Quick rule-of-thumb for mentally calculating Rate of Descent for a standard 3° glidepath slope

The Rate of Descent for a 3° glidepath (standard slope) can be roughly approximated by a general quick rule-of-thumb:

(Ground Speed / 2) x 10

For more accuracy, adjust the Ground Speed for any head or tailwind before using the above rule, as follows:

Subtract any headwind component from the Ground Speed
Add any tailwind component to the Ground Speed

Note: This rule-of-thumb only works for a 3° glidepath (standard slope).


   Copyright © 1998-2022 Dr. Jamie Alnasir. All Rights Reserved. Terms of Use