FAA Commercial Pilot Airplane (CAX)Navigation and Flight PlanningHard
A cross-country flight has two legs: the first leg is 120 NM flown at a groundspeed of 150 knots, and the second leg is 90 NM flown at a groundspeed of 120 knots. If the flight departs at 0915 local time, what is the estimated time of arrival at the destination?
- A1033
- B1042
- C1048
- D1055
Show answer & explanationAnswer & explanation
Correct answer: C. 1048
Leg 1 time = 120/150 = 0.8 hr = 48 minutes. Leg 2 time = 90/120 = 0.75 hr = 45 minutes. Total flight time = 93 minutes (1 hr 33 min). ETA = 0915 + 1:33 = 1048.
Why the other options are wrong
- A. This underestimates total flight time by about 15 minutes.
- B. This is 6 minutes short of the correctly summed leg times.
- D. This overestimates total flight time by about 7 minutes.
Multi-Leg ETA Calculation
Estimated time of arrival for a multi-leg flight is found by calculating the time for each leg (distance/groundspeed), summing them, and adding the total to the departure time.
- Leg time (hr) = leg distance (NM) / leg groundspeed (kt)
- Convert each leg's decimal hour to minutes for easy addition
- Add cumulative time to departure time to determine ETA
Memory trick: Leg by leg, add the time, then tack it onto departure's climb.