Learn to estimate flight time and fuel burn from route distance, winds and aircraft performance, then add taxi, alternate and reserve fuel.
Estimate flight time by dividing each route segment’s distance by its forecast groundspeed, then add climb, descent, approach and taxi time. Estimate fuel from the aircraft’s phase-specific fuel flow, then add taxi, contingency, alternate and final-reserve fuel. For general flight simulation, an aircraft-profile planner is the most reliable method.
What does flight time mean in a flight plan?
Flight time may mean airborne time, en-route time or the complete gate-to-gate block time, so establish which figure your planner is displaying.
- Airborne time: take-off to landing, including climb, cruise, descent and approach.
- En-route time or ETE: normally the calculated time along the planned route, although the exact definition varies between planners.
- Block time: taxi-out, airborne time and taxi-in.
- ETA: the expected arrival clock time, calculated from departure time plus the relevant elapsed time.
A common error is treating ETE as gate-to-gate time. Add realistic taxi and ground delays if you are planning an airline-style schedule.
How do I calculate flight time and fuel burn?
- Measure the actual route distance. Include departure and arrival procedures, airways, the approach and any expected vectors. Airport-to-airport straight-line distance usually underestimates the flight.
- Select the exact aircraft profile. Match the aircraft variant, engines and, where possible, the specific add-on. Enter payload and planned fuel because weight affects climb performance, cruise fuel flow and speed.
- Apply the forecast wind. Calculate each leg using groundspeed rather than indicated airspeed or true airspeed. The basic formula is
time in hours = distance in NM ÷ groundspeed in knots. - Calculate each flight phase. Use performance data for climb time, climb distance and climb fuel. Do the same for cruise, descent and approach rather than applying one cruise figure to the entire route.
- Calculate trip fuel. For each phase, use
fuel used = time × fuel flow, then total the results. Include engine start, taxi and auxiliary-power-unit consumption where the simulated aircraft models them. - Add reserves and verify limits. Add contingency, alternate, final-reserve and any extra fuel required by your planning policy. Check usable tank capacity and maximum zero-fuel, take-off and landing weights where those limits apply.
Dedicated tools automate most of this work. Our comparison of planners that model winds, time and reserves explains which options suit quick VFR estimates and which support detailed aircraft profiles.
Worked manual estimate
Suppose the planned route is 240 NM and the estimated average groundspeed, including slower climb and descent phases, is 120 knots. The airborne estimate is 240 ÷ 120 = 2.0 hours.
At an illustrative average trip consumption of 10 US gallons per hour, trip fuel is 20 gallons. Adding 1 gallon for taxi and a 45-minute reserve calculated at 8 gallons per hour adds another 7 gallons, giving 27 gallons before any contingency, alternate or extra fuel. This is a rough cross-check, not a substitute for phase-specific performance data.
Which fuel-planning method should I use?
Use an aircraft-profile planner for complex IFR flights and a manual calculation for simple aircraft or as a sanity check.
| Method | Best used for | Main limitation |
|---|---|---|
| Manual calculation | Light aircraft, short VFR flights and checking another estimate | Climb, descent and changing winds are easily oversimplified |
| Simulator flight planner | Fast route and time estimates with default aircraft | Fuel predictions may not match a detailed add-on or exact operating technique |
| Aircraft-profile planner | Airliners, turboprops and longer IFR routes | Results depend on the correct profile, payload, altitude and weather |
| FMS or EFB prediction | Updating estimates after the route and aircraft have been loaded | May not include every dispatch reserve or ground allowance |
If you use SimBrief, our aircraft-and-route setup walkthrough covers the inputs behind its time and fuel calculation. In Microsoft Flight Simulator, also verify the routing and altitude using our guide to checking the MSFS built-in flight planner before trusting its estimate.
How much reserve fuel should I add?
Reserve fuel should be calculated separately from the fuel expected to be consumed between take-off and landing.
- Taxi fuel covers engine start and movement before take-off.
- Trip fuel covers take-off through landing on the planned route.
- Contingency fuel covers ordinary deviations from the forecast or plan.
- Alternate fuel covers a missed approach followed by flight to the selected alternate, when required.
- Final-reserve fuel is intended to remain available at landing.
- Extra fuel may cover anticipated holding, delays or limited diversion choices.
There is no universal reserve figure for every aircraft and operation. Real-world requirements differ by flight rules, jurisdiction and operating policy. For simulation training, choose the applicable policy before calculating fuel rather than adding an arbitrary percentage afterwards.
Why is the simulator burning more fuel than planned?
Actual burn usually exceeds the estimate because the aircraft profile, winds, route, weight or power settings differ from the plan.
- The planner uses a different engine or aircraft variant.
- The planned route omits procedures, vectors or a lengthy approach.
- True airspeed is mistaken for groundspeed, particularly in a strong headwind.
- Cruise fuel flow is applied to climb and approach, or descent burn is treated as zero.
- The aircraft is flown faster, lower or heavier than planned.
- Anti-ice, auxiliary power or other systems add consumption where the aircraft models them.
- Pounds, kilograms, litres and US gallons are mixed. Avoid converting jet fuel volume with a guessed fixed density when the aircraft or planner supplies a mass value.
- The add-on’s flight model does not match the published performance profile.
Check progress at the top of climb and at major waypoints: compare actual fuel remaining with planned fuel remaining, not just the tank percentage. If an add-on consistently differs under comparable conditions, record its actual climb, cruise and descent consumption and apply a fuel-bias adjustment where the planner supports one.