Flight Planning
ETA Calculator
Estimated time of arrival from departure time, distance, and ground speed.
Inputs
nm
kt
Result
Estimated time of arrival
16:00
Same day
Time en route
1.5 hours
1:30
Total minutes
90min
Formula
Ref- Time en route = distance ÷ ground speed
- ETA = departure time + time en route (wraps past midnight)
Worked example
RefDepart 14:30Z, 210 nm to run at 140 kt ground speed.
- 1.Time en route = 210 ÷ 140 = 1.5 h = 1:30.
- 2.Arrival = 14:30 + 1:30 = 16:00Z.
ETA 16:00Z (1:30 en route).
How it works
RefEstimated time of arrival is the departure (or overhead) time plus the time en route, which comes from the distance still to run and the ground speed. Recomputing ETA at each fix as ground speed changes is how you keep an accurate arrival estimate and meet slot or curfew times.
DGCA student tip
ExamWork in a single time zone — aviation uses UTC (Z). 1 nm per minute needs 60 kt ground speed, a handy anchor: at 120 kt you cover 2 nm a minute, so 210 nm ≈ 105 minutes.
Common mistakes
Watch- Using TAS instead of ground speed, so the ETA ignores wind.
- Mixing local time and UTC in the same calculation.
- Forgetting to roll the clock past midnight for long legs.