July 2, 2020
Weather, ELT Type Cited in 172 Crash Report
The Transportation Safety Board (TSB) released its report this week into the fatal crash in December 2019 of a Cessna 172H on Vancouver Island, British Columbia, in which its pilot, the sole occupant, was killed.
The aircraft, based at Courtenay Airpark (CAH3) near Comox, was being used to take air samples at specific altitudes up to 17,500 feet above sea level (ASL) on behalf of the National Oceanic and Atmospheric Administration (NOAA), an American government agency. The air samples were part of NOAA’s program of greenhouse gas monitoring, and the occurrence pilot had been performing similar flights every 12 days since 2002. The location being surveyed was one of many around North America.
The mission started with air sampling at 17,500 feet, then continued sampling at lower altitudes. When the sampling point at 9,500 feet ASL was reached, the aircraft did not level off as required, but continued downward on the same heading at a descent rate averaging 1,800 feet per minute. The last altitude picked up by radar was 2,800 feet ASL. There was no communication with the aircraft’s pilot. The Cessna crashed into a forested hillside near Stewardson Inlet and was destroyed on impact. Evidence at the scene indicated that the engine was developing power at the time of impact.
The 172 had been modified by the replacement of its standard 145-hp Continental O-300D engine with a Lycoming O-360-A4M via a Supplemental Type Certificate (STC). It was also equipped with a supplementary oxygen system in the form of a tank with a cannula, but its valve was found in the OFF position with 500 psi remaining.
Weather conditions at the time included an overcast layer at 4,700 feet above ground level (AGL), with the presence of icing conditions and convective activity.
Local authorities were informed when the aircraft did not return when expected – however, the Rescue Coordination Centre in Victoria, B.C. was not notified until five and a half hours after the accident. Although the aircraft’s ELT was triggered, it was an older model transmitting on 121.5 MHz, a frequency no longer monitored by satellites. Due to poor visibility and inclement weather, a Search and Rescue team was not able to reach the crash site until the following day.
In their report, the TSB reiterates its recommendation A16-01 following a 2016 accident that:
the Department of Transport require all Canadian-registered aircraft and foreign aircraft operating in Canada that require installation of an emergency locator transmitter (ELT) to be equipped with a 406 MHz ELT in accordance with International Civil Aviation Organization standards.
The complete TSB report is appended below.
Photo credit: TSB