The Unbalanced Approach at Minimum Fuel
You are the pilot-in-command of a twin-engine turboprop on a scheduled IFR flight. While en route at FL200, ATC advises that weather at your destination has deteriorated to 300 ft ceiling and 1200 m visibility, with the ILS runway 27 in use. Your company operating minima for this approach are 200 ft DH and 550 m RVR, but the aerodrome requires a 15% increase in minima when the runway is contaminated and braking action is reported as medium. You have 45 minutes of usable fuel above your final reserve, no suitable alternate within 20 minutes, and one passenger reports feeling unwell. The first officer suggests continuing and reassessing on final approach. Descent clearance has been issued.
1. As PIC, what is the correct decision regarding continuation of the approach, and what factors must you weigh?
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You must apply the applicable operating minima before continuing. The reported ceiling of 300 ft is above the 200 ft DH, and 1200 m visibility is above the 550 m RVR, so the raw weather does not prohibit the approach. However, the contaminated runway triggers the 15% increase: DH becomes 230 ft and RVR becomes approximately 633 m. The 300 ft ceiling still satisfies this, and 1200 m visibility still satisfies the increased RVR. The decisive factor is fuel and alternate availability. With 45 minutes above final reserve and no suitable alternate within 20 minutes, you must confirm that the destination weather, including the increased minima, will allow a landing. If a missed approach occurs, you have 45 minutes to divert, which is marginal. The ill passenger adds urgency but does not override safety. The correct decision is to continue the approach while briefing the missed approach and diversion options, and to set a firm commitment point: if the aircraft is not stable by 500 ft or the reported RVR falls below 633 m, you go around and divert immediately.
2. What does the 15% increase in minima mean operationally, and how should it be applied?
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The 15% increase applies to the published operating minima for the approach. The decision height increases from 200 ft to 230 ft, and the RVR requirement increases from 550 m to approximately 633 m. This reflects the reduced braking action and the greater stopping distance required on a contaminated runway. Operationally, you must ensure that the reported RVR at the touchdown zone meets or exceeds 633 m before commencing the final approach, and you must not descend below 230 ft unless the required visual references are established. If the RVR is reported as 600 m, the approach cannot be continued. The increase also affects the missed approach and landing roll considerations, so you should brief the longer landing distance and the possibility of a go-around at the higher decision height.