Landing distance at Rodrigues with tailwind and water
You are planning a landing at Sir Gaëtan Duval Airport, Rodrigues (FIMR), runway 32, LDA 1,100 m, elevation 95 ft. The AFM gives a landing distance over 50 ft of 980 m at 2,200 lb, 1,000 ft pressure altitude, 30°C, no wind, dry runway. Actual conditions: QNH 1012, temperature 30°C, wind 140/10 kt, runway 32 wet with standing water in patches. Your aircraft is at 2,250 lb. You have 1 h 15 min of fuel remaining, enough for one approach and diversion to FIMP (35 minutes away) but not for extensive holding. The runway is the only one at Rodrigues; there is no ILS. A go-around would require a visual circuit. You are one of two pilots; the other has 120 hours total time. The tower reports braking action medium.
1. Estimate the effect of the conditions on landing distance and decide whether a straight-in landing is acceptable.
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Start with the AFM figure of 980 m, which already accounts for 1,000 ft pressure altitude and 30°C. The aircraft is 50 lb above the reference mass, roughly 2.3%, so add a small amount, perhaps 10 to 20 m. The significant factors are wind and runway condition.
Use a conservative planning factor of 10% per 5 kt of tailwind. A 10 kt tailwind gives about +20%. A wet runway with standing water and medium braking gives at least +15%. The adjusted distance is approximately 980 x 1.20 x 1.15 = 1,352 m, plus the mass allowance. That exceeds the 1,100 m LDA by a wide margin.
Even using a less conservative 10% total tailwind allowance, the distance is about 1,240 m, still greater than the LDA. A straight-in landing on runway 32 is not acceptable. Request runway 14 into wind if it is available and dry enough; otherwise divert to FIMP while you still have fuel and daylight. Do not plan to use medium braking as a substitute for stopping distance.
2. What operational factors could make the actual distance worse than the calculation?
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Standing water can cause dynamic hydroplaning, especially at higher touchdown speeds, and medium braking may become poor over patches. A tailwind increases ground speed at touchdown and reduces the time available to stop. If the approach is high or fast, the aircraft will touch down deeper than the 50 ft point, consuming margin that the AFM figure assumes.
Runway slope, gust spread, and high density altitude also matter. Rodrigues is only 95 ft elevation, but 30°C still raises density altitude and true airspeed. A go-around from a late touchdown would require a visual circuit with limited fuel. The second pilot's 120 hours total time is not a factor in the calculation, but it does affect crew coordination and the decision to divert early. If braking action is medium and water is visible, treat the runway as contaminated rather than merely wet.
3. How should fuel and diversion planning affect your decision?
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You have 1 h 15 min of fuel and the diversion to FIMP takes 35 minutes. That leaves 40 minutes after diversion, which is adequate for a normal VFR reserve but not for extensive holding or a second approach at Rodrigues. If you attempt an approach and go around, you may not have enough fuel to reach FIMP with reserve.
The correct planning decision is to divert before the approach if the landing distance is unacceptable. Do not fly the approach to see how it feels; that consumes fuel and commits you to a low-energy situation. If you are already committed and the landing cannot be made safely, declare minimum fuel or urgency, proceed directly to FIMP, and land with the reserve you have. A go-around at Rodrigues with 1 h 15 min fuel is a contingency, not a plan.