Landing Runway Distance Calculator

Landing distance vs. runway: LDR = air segment + ground roll

Landing Distance Required (LDR) covers two pieces: the airborne segment from a 50 ft threshold-crossing height through the flare, plus the ground roll from touchdown to a full stop under normal braking. A lot feeds into it — landing weight, approach speed V_REF (usually 1.3·V_S0), pressure altitude, temperature, runway slope, the headwind or tailwind, and how much grip the surface offers when it's dry, wet or contaminated. For scale, a Cessna 172 needs roughly 180 m on a dry runway, while a Boeing 737-800 at typical landing weight wants around 1500 m. RBAC 121 requires that the runway available for jets be at least 1/0.6 = 1.67× the demonstrated LDR, which is another way of saying the LDR can't eat up more than 60% of the runway. Modern airliners stop with reverse thrust, spoilers (lift dumpers) and antiskid wheel brakes working in concert.

Applications

Pilots and dispatchers reach for this kind of number when planning landings under RBAC 121/135, deciding when to go around after overshooting the touchdown zone, applying wet or contaminated runway corrections, picking an autobrake setting, checking whether an alternate airport will actually work, and running short-field drills in general aviation training.

FAQ

Why is the 60% rule important? It builds in slack for the things that go wrong on a real approach: shifting conditions, a late touchdown, fading brakes, a contaminated surface. Strip that margin away and one bad parameter on its own could run you off the end.

How much does a wet runway cost? A wet surface typically tacks on about 15% to the LDR. Standing water or slush is far worse and can stretch the dry distance to two or three times its length.

When should you go around? Call the missed approach if you aren't stabilized by 1000 ft AGL on IFR or 500 ft on VFR, if you touch down past the touchdown zone, or if you feel the aircraft floating too long before settling.