Runway Slope Landing Distance Calculator

The factor covers the ground roll physics — a weight component opposing the brakes. What it can't price is the flare: rounding out over terrain that falls away, the airplane floats at a nearly constant height above a descending surface, converting what looks like a normal flare into hundreds of feet of glassy drift. Pilots consistently report downhill touchdowns 'way long' — that's the geometry, not the technique.

Convert and compare: 1% of grade is worth roughly 2 kt of wind for landing trades. A 3% strip landed uphill with a 6-kt tailwind beats the same strip landed downhill into 6 kt of headwind in most light aircraft — gravity braking on rollout plus a flare against rising ground outvalue the airspeed difference. Strips steeper than ~2% are effectively one-way regardless of the windsock, which is exactly how their published procedures read.

The ground rises to meet you, compressing the float and steepening the apparent approach. Carry a touch of power into the flare, expect the touchdown sooner than the sight picture suggests, and don't trim for the visual glideslope illusion (an upslope makes a normal approach look steep, tempting a dangerously flat dragged-in arrival — the same illusion working for you on rollout works against you on final).

AIP/Chart Supplement entries publish significant gradients; for bush strips, threshold elevations differenced from satellite terrain data, the strip's own published guide (many one-way strips have community-maintained pages), or a phone call to the operator. Walking it remains the gold standard — average slope hides the steeper section, and it's invariably at the end where you'll arrive fastest.