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Equal Time Point Calculator

Calculate the Equal Time Point (ETP) and Point of No Return (PNR) for long-distance flights. Enter route distance, TAS, and wind to find the halfway-time fix.

Route

Total Route Distance

True Airspeed (TAS)

kts

Headwind (+) / Tailwind (-)

kts

GS Outbound450 kts

GS Return450 kts

Equal Time Point

ETP Distance1,000nm

ETP Position50.0% of route

Time to ETP2h 13m

Continue = Return2h 13meach way

2h 13m to continue = 2h 13m to return

DEP

ETP

DEST

About

The Equal Time Point (ETP) is the position along a route where the time to continue to the destination equals the time to return to the departure point. It is essential for oceanic and long-range operations where diversions mid-route require immediate divert decisions. The Point of No Return (PNR) is the furthest point you can reach and still have enough fuel to return.

How to Use

1Enter the total route distance in nautical miles.
2Enter your planned True Airspeed (TAS) in knots.
3Enter the average headwind component - positive for headwind, negative for tailwind.
4The ETP distance and time display automatically once route and TAS are filled.
5Expand Point of No Return and enter fuel on board, burn rate, and reserve fuel to compute the PNR.

Tips

//A headwind on the outbound leg pushes the ETP closer to the destination because the return trip is faster.
//If the PNR is before the ETP, fuel is your constraining factor - you must divert before you reach the equal-time point.
//For ETOPS operations, each ETP is calculated for a specific alternate airport with its own wind and divert fuel burn.
//The route bar visualisation shows both ETP and PNR positions so you can see at a glance if fuel limits the decision point.
//Reserve fuel in the PNR section should match your actual regulatory reserve - typically 5% of trip fuel plus 30 min holding for ICAO long-range operations.

ETP / PNR Formulas

GS outTAS - headwind

GS returnTAS + headwind

ETP distD x GS_return / (GS_out + GS_return)

Endurance(fuel - reserve) / burn rate

PNR distendurance x GS_out x GS_return / (GS_out + GS_return)

All distances in NM, speeds in kts, fuel in consistent units (lbs or kg).

FAQ

What is the difference between ETP and PNR?: The ETP is purely a time-based calculation - it does not consider fuel. The PNR incorporates fuel: it is the furthest point where you can still return with your required reserves. If fuel is plentiful the PNR is further than the ETP; if fuel is tight the PNR may be before the ETP.
Why is the ETP not at the midpoint of the route?: Wind shifts the ETP. A headwind on the outbound leg means the return trip is faster, so the point of equal time is displaced toward the destination. With zero wind the ETP is exactly at the 50% mark.
When is ETP used in real operations?: ETP calculations are mandatory for oceanic and remote area operations (ETOPS, MNPS, RNP-4 airspace). They identify commitment points for divert decisions before you lose communication range or pass the last suitable alternate.