TAF, Freezing Rain, and VFR Arrival Planning
You are dispatched on a 2.5-hour commercial VFR flight in a non-icing-certified aeroplane. The terminal forecast for destination is: wind 24015G25KT, visibility 4 SM in light rain, broken cloud at 2,500 ft AGL, TEMPO 2 SM in heavy rain and broken cloud at 1,200 ft AGL. An enroute AIRMET warns of freezing rain above 4,000 ft. The freezing level is forecast at 4,000 ft. Your planned altitude is 4,500 ft. The aircraft has no de-icing equipment. The alternate is 40 minutes away and forecast VFR. You have 3.0 hours of fuel. A colleague suggests climbing to 6,500 ft to stay above the weather.
1. Interpret the destination forecast and decide whether a VFR arrival is assured.
Read the worked answer
The prevailing forecast (4 SM, BKN 2,500 ft) is VFR, but the TEMPO (2 SM, BKN 1,200 ft) is below the 3 SM minimum and leaves little vertical margin. TEMPO means the condition is expected to occur for part of the period, not that it is unlikely. A VFR arrival is therefore not assured.
The pilot should plan to hold, divert, or delay, and must confirm that the alternate is genuinely VFR at the arrival time. The 4 SM prevailing visibility does not authorize a landing during a 2 SM TEMPO period.
2. Evaluate the 4,500 ft and 6,500 ft altitude options in light of the freezing-rain AIRMET.
Read the worked answer
Freezing rain above 4,000 ft means known icing in that layer. A non-icing-certified aeroplane must not enter it. At 4,500 ft you would be in the warned layer; climbing to 6,500 ft makes the exposure worse, not better.
The safe options are to stay below the freezing level (for example 3,500 ft) only if terrain, obstacles, and VFR cloud clearance allow, or to delay/cancel. Do not treat the climb as an escape from icing. If the route requires 4,500 ft for terrain clearance, the flight cannot be conducted legally and safely in these conditions.
3. Check the fuel plan against the trip, alternate, and reserve.
Read the worked answer
Fuel required = trip + alternate + reserve = 2.5 h + 0.67 h + 0.5 h = 3.67 h. With 3.0 h of fuel, the planned alternate and reserve cannot both be supported; the flight is short by about 0.67 h (40 minutes).
Either add fuel, reduce the route, or nominate a closer alternate. Even with the fuel, the icing and TEMPO weather make this a no-go until conditions improve.