RNAV departure and NOTAM closure at Kota Kinabalu
You are planning a night IFR departure from Kota Kinabalu (WBKK) to Brunei (WBSB) in a Beechcraft King Air 200. Your route is via the RNAV (GNSS) departure and airway. The current NOTAMs state that the WBKK VOR/DME is unserviceable, the runway 02 ILS is unserviceable, and the RNAV (GNSS) approach to runway 20 is available. The ATIS reports wind 200°/12 kt, visibility 5 km in rain, broken at 1 200 ft, temperature 26 °C, QNH 1008 hPa. Your aircraft has a single GNSS receiver with RAIM prediction capability.
1. Determine whether your planned RNAV departure and route can be flown and what mitigations are required.
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The RNAV (GNSS) departure does not require the VOR/DME, so the VOR outage does not by itself prevent the departure. However, RNAV operations require the aircraft to have the appropriate navigation specification (RNAV 1 or RNP 1 for terminal areas) and valid RAIM prediction for the intended route and time. You must run a RAIM prediction for the departure and arrival; if RAIM is unavailable, the RNAV procedure cannot be used and a conventional departure must be planned. With a single GNSS receiver, you must also ensure a suitable conventional backup exists for the en-route phase should GNSS be lost. The ILS outage is irrelevant to departure but affects your return options if a diversion back to WBKK is needed.
2. The weather at WBKK is marginal. What departure and alternate considerations apply?
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Visibility 5 km in rain with broken cloud at 1 200 ft is above most take-off minima but the rain may reduce visibility below the aerodrome operating minima during the departure. You must confirm the take-off minima for the runway and whether a return-to-departure alternate is required. With no ILS and only the RNAV (GNSS) approach to runway 20 available, the alternate must have an approach that you can fly and that meets the weather requirements. The alternate weather must be at or above the alternate minima, including the additional margin for a non-precision approach. Given the QNH of 1008 hPa, the low pressure increases the true altitude relative to indicated altitude, which must be considered when assessing terrain clearance on the departure procedure.