Takeoff Runway Distance Calculator
Estimates single engine aircraft takeoff distance from weight, pressure altitude and temperature using typical aircraft manual corrections.
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Take-off distance vs. runway: TODR = ground roll + flare
Take-Off Distance Required (TODR) adds up two things: the ground roll until the aircraft rotates at V_R, and the airborne flare needed to clear a 35 ft obstacle. Several factors push it up. Weight W matters, so does pressure altitude and temperature (both of which raise density altitude), along with runway slope and any tailwind component. To put numbers on it, a Cessna 172 needs roughly 360 m at sea level in calm wind, while a Boeing 737-800 at MTOW wants about 1800 m. Runway 27R at Guarulhos (SBGR) runs 3700 m, so there is comfortable margin even for a B747. Under RBAC 121 the available runway has to exceed the TODR computed with an engine failure at V₁, and carriers end up trimming payload whenever the math doesn't close. As an example, take W = 2400 lb, PA = 2000 ft, OAT = 30 °C, which gives a TODR of about 540 m in a C172.
Applications
Pre-flight planning and W&B sheets. NOTAM-based go/no-go calls when works have shortened a runway. RBAC 121 mandatory take-off performance with the V₁/V_R/V₂ schedule. Hot-and-high analyses, corrections for a contaminated runway (water, snow, slush), and balanced-field length computations.
FAQ
What is balanced field length? It's the runway length where the accelerate-stop distance and the accelerate-go distance come out equal, which pins down the optimal V₁ for a given weight and the ambient conditions of the day.
Why is tailwind so penalizing? Every knot of tailwind raises the ground speed you need at rotation. That's why a lot of AFMs cap operational tailwind at 10 kt and call for hefty distance corrections.
Does runway slope matter? It does. An uphill slope brings in a gravity component that works against acceleration, and a 2% uphill on a 2000 m runway can tack 10-15% onto the TODR.
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Take-Off Distance Available (TODA)
Calculate the Take-Off Distance Available, TODA = TORA + clearway, from the Take-Off Run Available (TORA) and the clearway length. TODA is one of the four declared distances of a runway, central ICAO operational concepts. The clearway is an obstacle-free rectangular area beyond the runway over which the aircraft can complete the initial climb to a minimum height — it extends takeoff distance without extra pavement, since the aircraft is already airborne. The declared distances (TORA, TODA, ASDA, LDA) are published for each runway threshold and used by pilots and dispatchers to verify, for each takeoff, that the aircraft — with its weight, configuration and the day's conditions — fits the available runway with required margins. Enter the TORA and the clearway length.
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Aircraft Takeoff Speed
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Accelerate-Stop Distance Available (ASDA)
Calculate the Accelerate-Stop Distance Available, ASDA = TORA + stopway, from the Take-Off Run Available (TORA) and the stopway length. ASDA is one of the four declared distances and has a critical safety role: it is the distance available to accelerate to the decision speed (V₁) and, if the pilot aborts the takeoff (engine failure or other), still stop safely. The stopway is a paved (or adequately strong) area beyond the runway, able to bear the aircraft in an emergency stop, not used in normal operation. Unlike the clearway (for the airborne aircraft), the stopway is for the aircraft on the ground, braking. ASDA is decisive in the balanced field length concept: the point where the distance to continue takeoff (one engine out) equals the distance to abort and stop defines V₁ and the required runway length. Enter the TORA and the stopway length.
The results provided by this tool are for general informational and educational purposes only and do not constitute professional, financial, medical, legal, tax or accounting advice. Always confirm important decisions with a qualified professional and official sources.