The in-flight break-up of a Cessna 210 over the remote Northern Territory likely resulted from the charter aircraft entering an area of strong convective activity from a rapidly developing thunderstorm, an ATSB investigation has found.
On 24 December 2022, the Cessna 210N was conducting a charter flight under the visual flight rules from Gove to Katherine with a pilot and passenger on board.
A search and rescue was initiated when the aircraft failed to arrive at the planned time at Katherine Tindal Airport.
The following day, a wreckage field was located at a remote location in East Arnhem, approximately 237 km along the intended flight track. The pilot and passenger sustained fatal injuries.
"Weather satellite information showed the formation of a rapidly developing thunderstorm near to Bulman, during the time period the aircraft likely transited the region," ATSB Chief Commissioner Angus Mitchell said.
"The aircraft likely entered an area of strong convective activity from the thunderstorm, subjecting it to severe turbulence and reducing visibility for the pilot."
Analysis of the wreckage allowed the ATSB to determine that the aircraft's right wing had separated from the fuselage in flight, probably due to a combination of turbulence from the thunderstorm, airspeed above the aircraft manoeuvring speed, and control inputs.
The report notes this was the pilot's first period operating through a Northern Territory wet season.
"Why the pilot flew in close proximity to the storm could not be determined with certainty, however, it is possible that they were in the process of diverting or turning back when the break-up occurred and/or the severity of the storm was not apparent," Mr Mitchell noted.
"Rapidly developing thunderstorms are a feature of the wet season in the Northern Territory, with associated severe turbulence presenting pilots with a challenging and hazardous operating environment.
"Identifying and maintaining adequate clearance from thunderstorms is therefore critical to safe flight."
The US Federal Aviation Administration recommends remaining at least 20 NM (37 km) from thunderstorms.
"Weather radar and satellite imagery can assist planning and in‑flight storm avoidance, provided their limitations are understood, while contacting the duty BoM forecaster via the phone number on the relevant graphical area forecast is the best way for pilots to assess the viability of a planned route, particularly if the forecast is marginal and the weather is changing."
The Bureau's online Knowledge Centre is a valuable resource for pilots, as are CASA's annual Flying in the wet season seminars.
As a result of this accident, operator Katherine Aviation, which has since ceased operating, provided tracking and communication devices for all its pilots to enable real-time satellite-based tracking and monitoring of its fleet.
It also presented the theory component of its wet season training material to its pilots, and required all pilots to complete the briefing program on an annual basis.
Finally, the operator developed flight assessment tools to provide its pilots with better decision-making capability when planning for operations during marginal weather.
You can find here the report: In-flight break-up involving Cessna 210N, VH-TFT, 237 km east-north-east of Katherine, Northern Territory, on 24 December 2022
