Re your article on single-engine IFR flights (Flight International, 11-17 June), engine failure may not be the only hazard facing night single IFR operations.
Of 24 Cessna Caravan serious accidents, airframe icing was a factor in 17. In at least 11 of the 17, it would seem that the icing occurred before take-off and the aircraft was not de-iced. In the other six, it occurred in flight.
On 15 March, a pilot apparently departed with leading-edge ice from the previous sector, but was unable to maintain 4,000ft (1,200m) due to in flight icing. The controller advised that icing was not expected above 11,000ft; well-intentioned but impractical advice. A preceding Hawker jet reported no icing between 4,000ft and 5,000 ft. At 250kt (460km/h), a rapid climb through would probably prevent airframe icing, something the Cessna pilot could not benefit from.
Graham Smith
Tisbury, UK
Source: Flight International
