Runway Excursion Risk After an Unforecast Tailwind
A turboprop on an RBAC 135 scheduled sector is cleared for a visual approach to a 1,650 m runway, aligned 090°, dry, at aerodrome elevation 2,400 ft. The ATIS at 20 minutes out gave wind 080/8. On final, tower reports wind 260/14 gusting 22. The aircraft's landing distance required at the current mass, elevation, and temperature, with zero wind, is 1,180 m. The operator's manual requires the landing distance available to exceed the required distance by 15% for a dry runway and prohibits landing with a tailwind exceeding 10 knots unless the runway is longer than 2,000 m. The crew is on a stabilized approach at 500 ft, fully configured, on speed. The first officer is flying. The captain has 40 hours on type.
1. Compute the wind component and determine whether the landing is permitted under the operator's manual.
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Wind component. Runway heading 090°, wind 260° at 14 gusting 22.
The angle between runway heading and wind direction is 170°, which is nearly a direct tailwind. The tailwind component is therefore close to the full wind speed: about 14 knots steady and about 22 knots in the gust.
Against the manual. The manual prohibits a tailwind exceeding 10 knots unless the runway exceeds 2,000 m. The runway is 1,650 m. The steady tailwind alone is 14 knots, which exceeds 10 knots. The landing is therefore not permitted on this runway in this wind.
Against the performance requirement. The 15% margin on a dry runway requires a landing distance available of at least 1,180 × 1.15 = 1,357 m. The runway is 1,650 m, which satisfies the dry-runway margin on a zero-wind basis. But the zero-wind figure is not the operative figure: a tailwind of 14 knots increases the ground speed at touchdown and the stopping distance substantially, and the performance calculation must be recomputed for the actual tailwind. The 1,357 m figure is a floor, not the answer.
Conclusion. The landing is prohibited by the tailwind limitation regardless of the performance arithmetic. The correct action is a go-around and a re-evaluation, not a landing.
2. What should the crew do on the go-around, and what options exist at this aerodrome?
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The go-around is the correct and immediate action. On the go-around:
- Fly the go-around. Apply power, establish the climb, retract as appropriate, and fly the published or assigned go-around procedure. Do not attempt to troubleshoot while at low altitude.
- Communicate. Tell the tower the reason - tailwind on the landing runway - and request the reciprocal runway if one exists, or holding to await the wind.
- Reassess. The wind is 260/14 gusting 22, which is a direct crosswind on a reciprocal runway aligned 270°. That may be within the aircraft's crosswind limit, but the gust spread of 8 knots and the 2,400 ft elevation must be considered.
Options, in order of preference:
- Land on the reciprocal runway if it exists and the crosswind is within limits and performance is satisfactory. This is the cleanest solution.
- Hold and await an improvement if fuel permits, with a hard decision point on fuel.
- Divert to an aerodrome with a runway aligned into the wind and adequate length, if neither of the above works.
What must not happen is a second approach to the same runway with the same tailwind on the assumption that the first approach was somehow misjudged. The wind is the problem, and only a different runway or a different aerodrome solves it.
3. Assess the human-factors and crew-coordination aspects of this event, given the captain's 40 hours on type and the first officer flying.
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This is a classic authority-gradient and plan-continuation scenario, and it deserves explicit analysis.
- Low-experience captain. 40 hours on type means the captain is still building type-specific judgement. A captain with limited time on type is more likely to anchor on the original plan and less likely to have a well-developed sense of the aircraft's tailwind sensitivity.
- First officer flying. The pilot flying is focused on the approach path and speed. The pilot monitoring - the captain - owns the wind and the performance check. If the captain does not run that check, no one does.
- Plan continuation bias. The approach is stabilized, the aircraft is configured, and the runway is in sight. Every one of those factors pushes toward continuing. The wind report is the disconfirming evidence, and disconfirming evidence is exactly what plan continuation bias suppresses.
- The ATIS trap. The ATIS was 20 minutes old and gave 080/8. The crew formed a mental model of a light headwind. The new report contradicts that model, and the natural response is to distrust the new report rather than the old model.
- What good looks like. The captain should have called the wind aloud, computed the component, stated the manual limitation, and directed the go-around. The first officer should have been empowered to call it too. A brief before descent that named the tailwind limit and the go-around trigger would have made the decision automatic.
The lesson is procedural: put the wind limit and the performance recomputation into the approach brief as explicit numbers, so the decision does not depend on who notices the change.