Circle-to-Land at Night with a Tailwind and a Short Runway
You are cleared for a circle-to-land at night at an uncontrolled airport. The active runway is 1,200 m long, dry, at 600 m elevation, with an approach speed category that requires a circling area of 2.7 NM. The wind is reported 090/12 kt; the runway in use is 09. The circling MDA gives you 450 ft above aerodrome level. Your aircraft's landing distance required at the expected landing mass, from the AFM, is 900 m at sea level ISA; the airport is at 600 m and the OAT is 30 °C. You are visual with the runway environment. The first officer says "we're visual, let's just land."
1. Evaluate whether the landing distance is adequate, accounting for elevation, temperature, and the regulatory factor.
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The 900 m AFM figure is at sea level, ISA. At 600 m elevation and 30 °C, density altitude is roughly 600 + 120 × (30 − 15) ≈ 600 + 1,800 = 2,400 m equivalent, which increases true landing distance. A rough rule of thumb is about +3% per 1,000 ft of density altitude; 2,400 m ≈ 7,900 ft, so about +24%, giving ≈ 1,115 m.
Then apply the regulatory landing distance factor - for a dry runway, the required landing distance is typically 1.67 × the AFM landing distance (or the operator's approved factor). 1.67 × 1,115 ≈ 1,860 m.
That is far more than the 1,200 m available. Even without the factor, 1,115 m leaves only 85 m of margin on a 1,200 m runway at night with a crosswind component - unacceptable.
So the landing distance is not adequate. The first officer's "we're visual" is not a performance assessment.
2. Assess the circling manoeuvre itself: what are the risks at night here, and what does the 2.7 NM area imply?
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Circling at night at an uncontrolled airport is one of the higher-risk manoeuvres in commercial operations. Key points:
- The 2.7 NM circling area is the protected volume within which obstacle clearance is assured provided you stay within it and respect the MDA. At night, judging distance from the runway and staying inside the area is much harder - there is no visual horizon reference and few lights.
- MDA 450 ft AGL must be maintained until in a position to descend for landing; descending early at night is a classic CFIT setup.
- Uncontrolled airport - no tower, so you must self-announce, monitor the frequency, and accept that other traffic may not be talking. Traffic avoidance at night in a circling pattern is poor.
- Wind 090/12 on runway 09 is a direct headwind for landing, which is favourable, but if you circle to a different runway the wind may become a tailwind or crosswind - check the actual landing runway and its component.
If you cannot confidently stay within the circling area and maintain MDA to a safe landing position, do not circle - go around and divert.
3. What is your decision and what do you tell the first officer and ATC?
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Decision: go around and divert. The landing distance required (≈1,860 m with the factor) exceeds the 1,200 m available by a wide margin. This is not a judgement call - it is a performance limit. Circling at night adds risk on top of an already non-compliant landing.
To the first officer: explain the arithmetic - density altitude correction plus the landing distance factor - so the reasoning is shared, not just the decision. "Visual" is necessary but not sufficient; the runway has to be long enough.
To ATC (or on the uncontrolled frequency): announce the go-around clearly - "[callsign] going around, climbing to [altitude], diverting to [airport]." If the airport is uncontrolled, make the call on the CTAF/unicom so other traffic knows. Then plan the diversion, recompute landing distance for the diversion airport at the actual conditions, and brief the approach.