How do I calculate flight time and fuel burn?

Calculate flight time by dividing each route segment’s nautical miles by its forecast groundspeed, then add the segment times and any taxi allowance. Calculate fuel burn by multiplying each flight phase’s duration by its fuel flow, then add taxi fuel and the reserves your operation requires. For general flight simulation, use an aircraft-specific performance profile.

What does ETE mean in aviation?

ETE means estimated time en route: the predicted elapsed time between defined points on a flight, usually expressed as hours and minutes rather than a clock time. Check what the planner uses as its start and end points because ETE does not always include taxi or ground delays.

A mistake we see constantly is treating an airborne ETE as gate-to-gate time. If a planner predicts 1 hour 50 minutes from take-off to landing, taxi-out and taxi-in still need to be added to produce block time.

What does ETE mean in an FMC?

In an FMC or FMS, ETE is normally a continuously updated estimate of the time remaining to a waypoint or destination. It is calculated from the active route, present position, speed schedule, altitude, wind data and any programmed constraints.

An FMC prediction is not automatically a complete dispatch estimate. It may exclude taxi, holding, an alternate and protected fuel reserves. Some units display ETA as a clock time instead of ETE as a duration; a value such as 01:35 may mean 1 hour 35 minutes, while 16:20 may be an arrival time. The exact display convention depends on the aircraft.

Do not trust the destination prediction until the route is active and continuous, the performance data have been entered, and the aircraft has valid wind information. A route discontinuity or unexecuted change can make the displayed ETE misleading.

What is the estimated time of arrival formula?

The estimated time of arrival formula is ETA = departure time + elapsed flight time. Both values must use the same time standard, preferably UTC for aviation planning.

• For touchdown ETA, use the estimated take-off time plus airborne ETE.
• For on-block arrival, use the off-block time plus total block time.
• If departure is delayed, recalculate from the revised departure time rather than the published schedule.
• Carry the calculation into the next day when it passes midnight.

How do I calculate flight time?

Calculate flight time segment by segment using route distance and forecast groundspeed, then include climb, descent, approach and any required ground allowance.

1. Define the time you need. Decide whether the result should be airborne time, ETE between specific points, or complete block time. This prevents taxi from being omitted or counted twice.
2. Measure the planned route. Include departure and arrival procedures, airways, the approach and likely vectors. Straight-line airport distance usually produces an estimate that is too short.
3. Use the correct aircraft performance. Match the variant, engines and simulator add-on where possible. Weight, cruise altitude and speed schedule affect both elapsed time and fuel consumption.
4. Estimate groundspeed for each segment. Use groundspeed rather than indicated airspeed or true airspeed. For a direct headwind or tailwind, a rough estimate is true airspeed minus or plus the wind component; crosswinds require a proper vector calculation or planning tool.
5. Calculate and add the segment times. Treat climb, cruise, descent and approach separately. Using cruise speed over the whole route tends to underestimate short flights.
6. Add ground time where required. Include realistic taxi-out and taxi-in allowances for block time. Expected holding or extensive vectors should be identified separately rather than hidden inside the cruise estimate.

What are the time, fuel and distance formulas?

The basic time, fuel and distance formulas work when the units are consistent:

• time in hours = distance in NM ÷ groundspeed in knots
• time in minutes = distance in NM ÷ groundspeed in knots × 60
• distance in NM = groundspeed in knots × time in hours
• fuel used = fuel flow per hour × time in hours
• endurance = usable fuel available for consumption ÷ fuel flow per hour

Knots are nautical miles per hour, so do not combine nautical miles with miles per hour. Convert minutes to decimal hours before calculating fuel: 30 minutes is 0.5 hours. Likewise, 1.30 decimal hours means 1 hour 18 minutes, not 1 hour 30 minutes.

Worked flight time and fuel example

Consider an illustrative 240 NM simulator flight. The values below are deliberately simple and are not performance recommendations for a real aircraft.

The airborne time is 0.20 + 1.50 + 0.25 = 1.95 hours, or 1 hour 57 minutes. Trip fuel from take-off to landing is 3.6 + 15.0 + 2.0 = 20.6 US gallons.

Adding 0.8 gallon for ground running and an illustrative 45-minute reserve at 8 US gallons per hour gives 20.6 + 0.8 + 6.0 = 27.4 US gallons. Contingency, alternate and extra fuel would still need to be added if the planning policy requires them.

With take-off at 14:20 UTC, the touchdown ETA is 16:17 UTC. If the aircraft leaves the stand at 14:11, taxis out for nine minutes and spends three minutes taxiing after landing, its estimated on-block time is 16:20 UTC.

How do I calculate fuel burn and reserves?

Calculate expected fuel burn for each flight phase, then build the required fuel load by adding the applicable reserves and ground allowances.

A common block-fuel structure is taxi fuel + trip fuel + contingency fuel + alternate fuel + final-reserve fuel + extra fuel. Not every component applies to every simulated flight, but each should be considered separately:

• Taxi fuel covers engine start, auxiliary power where modelled, and movement before take-off. Add a separate taxi-in allowance when estimating complete gate-to-gate consumption.
• Trip fuel covers take-off through landing on the planned route.
• Contingency fuel covers ordinary differences between the forecast and actual flight.
• Alternate fuel covers the missed approach and flight to the selected alternate when applicable.
• Final-reserve fuel is protected fuel intended to remain available at landing, not extra trip endurance to spend routinely.
• Extra fuel may cover expected holding, delays, weather avoidance or limited diversion options.

There is no single reserve percentage suitable for every aircraft or operation. For a simulator flight, choose a clear policy before calculating the load. For real-world planning, use the approved aircraft data and the rules and procedures applicable to that operation.

Keep fuel units consistent. Do not mix pounds, kilograms, litres, US gallons and Imperial gallons. If the planner reports fuel by mass but the simulator loads it by volume, use the density supplied for that fuel and aircraft rather than a guessed conversion. Our guide to calculating, converting and loading simulator fuel covers capacity, weight limits and refuelling methods in more detail.

Which fuel planner should I use in a flight sim or MSFS?

Use a matched aircraft-profile planner for complex IFR flights, while a manual calculation is sufficient for a simple VFR estimate or an independent cross-check.

For an MSFS fuel planner, the built-in planning tools in Microsoft Flight Simulator 2020 and 2024 are useful for quick estimates, but detailed add-on aircraft often use their own EFB or FMS calculations. Importing a route does not guarantee that payload, reserves, winds and fuel have also transferred correctly.

For airline-style planning, our SimBrief aircraft-profile and MSFS workflow explains how route, payload and weather inputs affect the resulting time and fuel plan. For a free map-based planner, Little Navmap’s route and performance-profile workflow provides time and fuel estimates for many types of simulator flying.

Why is actual flight time or fuel burn different from the plan?

Actual results differ when the flown route, groundspeed, weight, weather, power settings or aircraft model do not match the assumptions used by the planner.

• The route is longer: check for added procedures, vectors, holds, route discontinuities or a different runway and approach.
• The flight takes longer: verify that the calculation used groundspeed rather than true or indicated airspeed, especially with a strong headwind.
• Climb burn is excessive: compare take-off weight, climb speed, power setting, temperature and anti-ice use with the profile.
• Cruise burn is excessive: check altitude, aircraft variant, engine type, speed schedule and whether the add-on uses a custom flight or engine model.
• The total is off by a large factor: look for mixed mass and volume units, US versus Imperial gallons, or minutes entered as decimal hours.
• The FMC estimate changes sharply: confirm that route changes have been executed and that destination, cruise altitude, reserves and wind data are valid.
• The planned fuel appears too high: make sure protected reserves are not being mistaken for fuel expected to burn before landing.
• Wall-clock time does not agree: pauses, accelerated simulation rate and simulator clock settings can separate real elapsed time from simulated airborne time.

At the top of climb and at major waypoints, compare actual fuel remaining with planned fuel remaining rather than looking only at tank percentage. A consistent difference under comparable conditions usually points to an unsuitable performance profile; where supported, correct it with a measured fuel-bias adjustment. We explain the other timing variables in our assessment of flight-time accuracy in simulators.