Probable Cause #59: Failure To Identify
This article originally appeared in IFR Refresher, July 2007.A turbocharged engine provides sea-level power to a higher altitude than a normally aspirated powerplant and is the main difference between the two. However, if a pilot is not totally familiar with the operation of turbocharged engines, it is entirely possible to misdiagnose a problem. Could that have happened here? On Feb. 22, 2006, at 1750 (PST) the pilot of a Beech 58P pressurized Baron contacted the Seattle AFSS requesting a standard briefing for an IFR flight from Bellingham, Wash., to Ogden, Utah. The pilot told the briefer he was planning on leaving Bellingham 20 minutes later and requested the winds for 12,000 and 18,000 feet. The briefer detailed a northerly flow aloft with an area of high pressure off shore and moisture due to a trough of low pressure at the lower levels in western Washington. AIRMETs for the entire route of flight called for occasional moderate turbulence below FL180, with turbulence above FL180 beyond Boise, Idaho. The area forecast predicted occasional moderate rime and mixed icing in clouds and precipitation from 2000 to 14,000 feet. The briefer also advised that icing could be expected in the descent from 12,000 feet nearly to the surface. Departure weather at Bellingham was reported as 3500 overcast and 10 miles visibility.