Cessna 180 N9247C accident near Whittier, Alaska

Probable cause

The pilot's decision to continue flight into known icing conditions, contrary to the airplane’s limitations, which resulted in a total loss of engine power due to icing.

NTSB analysis

The private pilot was conducting a personal cross-country flight in instrument meteorological conditions. The airplane was not certificated for flight into icing. A review of radar data and radio communications recordings revealed that, after an air traffic controller issued the pilot a descent from 10,000 to 8,000 ft mean sea level (msl), the pilot reported that he was having engine trouble and had encountered possible icing. The pilot subsequently declared an emergency, and 3 minutes later, radar contact and communication with the airplane were lost. A day after the accident, search and rescue personnel found the remains of the pilot along the eastern shoreline of Culross Island. The left main landing gear strut and tire were also recovered. The rest of the airplane was not located, and it is presumed to have sunk in Prince William Sound.

A review of weather information revealed that marginal visual flight rules conditions prevailed along the flight route due to low ceilings and that occasional instrument meteorological conditions (IMC) prevailed due to low ceilings and visibility in snow showers. Moderate icing was forecast between 4,000 and 10,000 ft above ground level. It is likely that the airplane encountered IMC and potential icing conditions below 10,000 ft msl. A pilot in an airplane about 6 minutes behind the accident airplane reported that, before descending from about 9,500 ft msl, he noticed a slight buildup of ice on the left engine cowling. Given this statement, the weather reports, and the accident pilot's report that he was having engine trouble, it is likely that the airplane flew through an area favorable for the formation of induction or carburetor icing, which resulted in a total loss of engine power.

A mechanic reported that the pilot had told him that when he applied carburetor heat, the control felt "mushy." The mechanic instructed the pilot to inspect the control arm for any damage because it could prevent the carburetor heat from operating correctly. Before the accident flight, the mechanic sent a text message to the pilot asking if he had checked the carburetor heat control, and the pilot replied that he had not but would do it that day. Therefore, although it is possible that damage to the carburetor heat control arm may have limited the amount of carburetor heat available to eliminate any possible carburetor ice, it could not be determined if this occurred because the airplane could not be examined.

Text from the NTSB. Open the NTSB docket for ANC15FA021 for the full record.