ILS with the glide path unserviceable and a tailwind on the runway
A Category C jet (Vref 135 kt) is arriving at Nairobi Jomo Kenyatta. NOTAM: ILS runway 06 glide path unserviceable until further notice. The published ILS 06 DA is 5,550 ft; the LOC-only MDA is 5,960 ft. The ILS MAP is at the DA, while the LOC MAP is 1.2 DME later. The missed approach for both is: climb straight ahead to 7,000 ft, then turn right. Weather: wind 200°/12 kt gusting 22 kt, visibility 4,000 m in rain, broken cloud at 1,200 ft, temperature 18°C, QNH 1018 hPa. The aircraft is cleared: "...cleared ILS runway 06 approach". The first officer, recently line-checked, sets the DA bug to 5,550 ft and starts briefing the ILS as normal.
1. Is the clearance acceptable as issued? What exactly must be flown, and what must change in the briefing?
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The clearance is not one the crew can fly as an ILS. The glide path is not serviceable, so there is no vertical path guidance; the clearance phrase reuses the name of the procedure but the only usable component is the localiser. Query ATC to confirm the LOC-only approach, and if there is any doubt ask for "LOC runway 06 approach" explicitly.
Changes to the briefing:
- Bug the LOC MDA of 5,960 ft, not 5,550 ft. Descending to 5,550 ft on a LOC approach is an unauthorised descent 410 ft below minima.
- The MAP moves: the LOC MAP is 1.2 DME beyond the ILS MAP, so the missed approach is initiated later than the crew is used to. Brief it by DME (and by time if DME is unavailable), not by the glide path.
- Fly a step-down profile or a constant 3° path calculated to arrive at the MDA at the MAP; do not chase a non-existent glide path.
- Rebrief the missed approach: climb straight ahead to 7,000 ft, then right turn.
The first officer's set-up is the exact trap the scenario is testing: familiar clearance, wrong minima.
2. Assess the wind and its effect on this approach and landing.
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Wind 200° on runway 06 is a large tailwind component. The angle is 140° off the runway heading, so the tailwind is roughly 12 × cos 40° ≈ 9 kt, gusting to about 17 kt. The aircraft's approach and landing tailwind limit is typically of the order of 10–15 kt, so the gusts are at or beyond the limit.
Consequences:
- Higher ground speed on final for the same IAS, so the visual segment passes more quickly and the landing distance required increases.
- The 4,000 m visibility is above minima, but a wet runway plus a gusting tailwind consumes much of the landing distance margin. Check the actual landing distance against the available distance, not just the minima.
- On a LOC-only approach there is no vertical guidance to help manage the higher ground speed; the descent to the MDA has to be planned more carefully.
Brief the possibility of a go-around early, and if the tower-reported tailwind exceeds the aircraft limit, do not commence the approach - hold or divert. At a single-runway aerodrome there may be no reciprocal option.
3. At 5,900 ft you have the runway in sight but you are high and fast. What do you do?
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Go around. The LOC approach has a MAP further along the track, but the MDA is a minimum, not a target, and being high and fast with a tailwind is the classic unstable approach. The stabilised-approach criteria - on speed, on path, correct sink rate, landing configuration by the specified gate - are not met, and the tailwind means the aircraft will float and use far more runway than planned.
Execute the published missed approach exactly: climb straight ahead to 7,000 ft, then turn right. Do not turn early, because the turn is protected only above 7,000 ft and the local terrain and the departure tracks of other aircraft are the reason for the restriction. Do not descend below the MDA during the go-around. Advise ATC, state the reason, and then decide whether a second approach is sensible: with a 17 kt gusting tailwind the conditions will not have changed. The better decision is to hold for an improvement or divert, with the fuel checked before the second approach is accepted.