Bonanza ices up

This December 2009 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.

Aircraft: Beech Bonanza. Injuries: None. Location: Dodge City, Kan. Aircraft damage: Substantial.

What reportedly happened: The pilot stated that the pitot heat system was working when he checked it during preflight. He obtained a full weather briefing from flight service, and checked the weather via the Internet before departing. While airborne at 6,000 feet to 6,500 feet MSL, he encountered instrument meteorological conditions and turned on the pitot heat.

Sometime later, the airplane encountered moderate icing conditions. The airspeed indicator stopped working and the pilot diverted to an alternate airport. While over the runway on landing approach, the airplane stalled and landed hard, substantially damaging the airplane.

Ice was found at the impact site, on the airplane’s surfaces, and in the pitot tube. Inspection of the pitot tube revealed the pitot heat was not functioning. On the day of the accident there were two AIRMETs for moderate icing in effect for the pilot’s route of flight and altitude. The pilot could not recall being informed of the icing conditions during his weather briefing and his briefing from flight service could not be located.

Probable cause: The failure of the pitot heat system in icing conditions, resulting in an inoperative airspeed indicator, which led to an inadvertent stall while on final approach. Contributing to the accident was the pilot’s decision to fly into known icing conditions.

For more information: NTSB.gov; NTSB Identification: CEN10LA068