Pre-flight Planning
Both the instructor and the student pilot assessed weather forecasts during pre-flight planning. They planned to land at Warrnambool before 1400, which was before the forecast deterioration at that airport was expected to begin. However, they did not evaluate the forecast for area B on the Graphical Area Forecast (GAF), which also predicted deterioration starting at 1400.
Because the flight departed more than 60 minutes after the forecasts were obtained, updated forecasts were required. The weather information had not changed significantly. The delayed departure and time spent on the ground at Warrnambool increased the likelihood of encountering the forecast deteriorating weather.
Weather Assessment During Ground Stop
While at Warrnambool, the instructor checked weather for the return flight using the Terminal Aerodrome Forecast (TAF) for Warrnambool and surrounding airports, rather than the area forecast and Moorabbin TAF. This was a missed opportunity to identify the reduced visibility and low-level cloud later encountered.
Since the instructor planned to return to Warrnambool if conditions deteriorated, they should have assessed the forecast for Warrnambool as a destination. The TAF included a TEMPO with conditions below alternate minima, requiring planning for an alternate airport or sufficient fuel to hold for one hour. The aircraft had refueled at Warrnambool and had enough endurance for holding. When planning for holding, consideration should also be given to likely weather conditions—in this case, forecast visibility of 4,000 m and broken cloud at 800 ft AGL. The flight crew had experienced the rapidly changing weather environment, and consideration should have been given to how they would hold for one hour in potentially poor conditions.
Departure and Return Flight
Before departing Warrnambool, the instructor did not adequately reassess conditions at Moorabbin, though conditions were suitable for the return flight. Shortly after departure, conditions deteriorated, prompting a decision to return to Warrnambool. During the return, the aircraft encountered forecast conditions no longer suitable for VFR flight. The instructor climbed and entered cloud.
The instructor held an instrument rating but had not practiced instrument flying in eleven months. Additionally, the aircraft was not certified for instrument flight. While in cloud, the instructor was aware they were not current and had never flown with reference to instruments from the right seat, requiring them to view instruments at an angle across the cockpit. They minimized control movements to maintain control and contacted Air Traffic Control (ATC) as soon as possible to advise of their situation and request assistance. This allowed the instructor to focus on flying and expedite a return to visual flight conditions.