9 / 20
If you want to follow a 3.25° glideslope (ILS), when TAS is 130 kt and wind component is 15 kt tailwind, your rate of descend must be:
  • A
    510 feet/min
  • B
    675 feet/min
  • C
    748 feet/min
  • D
    832 feet/min

Calculate rate of descent (ROD) on a given glide-path angle or gradient using the following rule of thumb formulae:

  • ROD (ft/min) = GP° × GS (NM/min) × 100
  • ROD (ft/min) = GP % × GS (kt)

Using the first formula, we will get:
ROD (ft/min) = 3.25 x (145/60) x 100
ROD (ft/min) = 785 ft/min

The precise calculation is:
ROD (ft/min) = Tan (3.25º) x GS (kt) x 6080/60
ROD (ft/min) = 834 ft/min

The results obtained from the rule of thumb (first formula used) are usually slightly lower than reality. Unfortunately, in this case, there is a big gap between the results obtained. On multi-choice answers, choose the higher option if calculating using the first formula only.

Note: This question was seen in a Performance exam. However, there is no matching to this question under 032. Please contact us if you come across this question.

Your Notes (not visible to others)

This question has appeared on the real examination, you can find the related countries below.