Crosswind Landing at Cochabamba
You are landing a Cessna 172 at Jorge Wilstermann International Airport (Cochabamba), elevation 8,300 ft, on runway 14. The reported wind is 200° at 18 kt gusting to 26 kt. The runway is 3,800 m long and 45 m wide. The aircraft's maximum demonstrated crosswind component is 15 kt. You are on final at 75 kt IAS with full flaps, and the density altitude is about 11,500 ft. The threshold is displaced by 300 m due to construction.
1. Calculate the crosswind and headwind components and decide whether the landing is within limits.
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The wind is 200° and the runway is 14, so the angle between wind and runway is 200 − 140 = 60°. The crosswind component is 18 × sin 60° = 18 × 0.866 ≈ 15.6 kt, and the gust component is 26 × 0.866 ≈ 22.5 kt. The headwind component is 18 × cos 60° = 9 kt, gusting to 13 kt. The steady crosswind of about 15.6 kt already exceeds the maximum demonstrated crosswind of 15 kt, and the gust value of 22.5 kt is well beyond it. The landing is therefore outside the demonstrated crosswind limit and should not be attempted on runway 14 under these conditions. The pilot should consider runway 20 if available, which would give a nearly direct headwind, or divert to an alternate aerodrome with a more favourable runway orientation.
2. How does the high density altitude affect the approach and landing?
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At a density altitude of about 11,500 ft the true airspeed for 75 kt IAS is significantly higher, so the ground speed on approach is greater and the landing distance increases. The engine produces less power, so a go-around will have a shallow climb gradient and the aircraft will take longer to accelerate and climb away from the ground. The pilot should fly a stabilised approach at the recommended speed, add a margin for the gust, and be prepared to go around early if the approach is not stable. The landing flare should be positive and the aircraft should be flown onto the runway rather than floated, because the higher ground speed and reduced power make a late go-around risky. The displaced threshold reduces the available landing distance by 300 m, so the touchdown point should be planned accordingly.
3. What technique should be used for the crosswind landing, and when should a go-around be initiated?
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The recommended technique is the wing-low method: lower the upwind wing into the wind to counteract drift and apply opposite rudder to keep the aircraft aligned with the runway centreline. As the aircraft approaches the ground, the wing-low attitude is maintained and the aircraft is flared, touching down on the upwind main wheel first. The pilot should not attempt to land with a crosswind beyond the demonstrated limit, and should go around if the aircraft cannot be kept aligned with the centreline, if the drift cannot be controlled, or if the approach becomes unstable. Given the gusty conditions and the high density altitude, the pilot should set a personal limit and be prepared to divert rather than force a landing.