FAA Instrument Flight Instructor (FII)IFR Procedures and ApproachesMedium
A pilot is flying an RNAV (GPS) approach with LNAV minimums. The final approach segment begins at 2,500 feet MSL at the FAF and the MDA is 800 feet MSL. The distance from the FAF to the MAP is 4.0 NM. Assuming a ground speed of 120 knots, what is the approximate time from the FAF to the MAP?
- A2 minutes 0 seconds
- B1 minute 30 seconds
- C2 minutes 30 seconds
- D3 minutes 0 seconds
Show answer & explanationAnswer & explanation
Correct answer: A. 2 minutes 0 seconds
To calculate the time from FAF to MAP: Time = Distance / Speed. Given distance = 4.0 NM, and speed = 120 knots. Time = 4.0 NM / 120 knots = 0.0333 hours. To convert hours to minutes, multiply by 60: 0.0333 hours * 60 minutes/hour = 2.0 minutes. The altitude information (FAF and MDA) is extra information not needed for this specific calculation.
Why the other options are wrong
- B. This time is too short for the given distance and speed.
- C. This time is too long for the given distance and speed.
- D. This time is significantly too long for the given distance and speed.
Time from FAF to MAP Calculation
The time from the Final Approach Fix (FAF) to the Missed Approach Point (MAP) on an instrument approach is calculated by dividing the distance between these two points by the aircraft's ground speed.
- Formula: Time (hours) = Distance (NM) / Speed (knots).
- Convert hours to minutes by multiplying by 60.
- Crucial for timing non-precision approaches without DME or GPS.
Memory trick: Time is Distance over Speed, for the MAP.