What happened
On 29 October 2007, a Cessna 340A RAM III, registration D-ICFG, departed St. John’s International Airport in Newfoundland, Canada, bound for Ponta Delgada in the Azores. The flight, operated by Air 7 GmbH, carried a pilot and one passenger.
During the transatlantic crossing at FL 210, the aircraft encountered weather conditions that deviated significantly from the initial forecasts provided by the German Weather Service (DWD). The pilot encountered stronger headwinds than anticipated and encountered a dense line of Cumulonimbus clouds. To avoid a significant increase in flight time and fuel consumption, the pilot chose to fly through the area, which resulted in the aircraft accumulating ice on the wings. This icing caused a reduction in indicated airspeed of approximately 20 knots and increased aerodynamic drag.
As the flight progressed, the pilot recalculated the remaining fuel and determined that while the destination at Ponta Delgada was reachable, there would be insufficient reserves to account for potential holding or a diversion to the alternate airport. Upon entering the Santa Maria Flight Information Region, the pilot requested a diversion to Flores Island. Because Flores is not an international airport with customs facilities, the pilot was required to declare an emergency to facilitate the landing. The aircraft landed safely at Flores Airport at 17:59 UTC.
The investigation
The GPIAAF investigation examined the flight planning, meteorological data, and aircraft performance. The investigation noted that the pilot had relied on weather briefings from the DWD but had not consulted Canadian Flight Information Centre sources for more localized data. The team analyzed the discrepancy between the forecasted winds and the actual conditions encountered, as well as the impact of icing on the aircraft's endurance.
Findings
- The Cessna 340A was not sufficiently refueled to safely manage the unexpected flight duration, potential holding, and diversion to an alternate airport.
- Encountering adverse weather conditions, specifically stronger headwinds and icing, acted as a contributory factor by reducing ground speed and increasing fuel consumption.
- The pilot's calculated margin for error was extremely slim, with only approximately 20 minutes of endurance available for holding and missed approach procedures.
- The decision to declare an emergency was a necessary regulatory requirement to land at a non-international airfield like Flores.