Narrative:Convair 580 ZK-KFU was scheduled for 2 regular return night freight flights from Christchurch to Palmerston North. At 20:32 flight AF 642 started its takeoff from runway 20 on schedule and climbed to FL210. The flight progressed normally. At 21:13 the Wellington controller cleared the flight to descend initially to FL130 and later to FL110. After contacting Ohakea Control the crew were further cleared down to 7000 feet and were given vectors for the approach to Palmerston. The aircraft descended through an area of forecast severe icing, which was probably beyond the capabilities of the aircraft anti-icing system to prevent ice build-up on the wings and tailplane. The aircraft then probably stalled because of a rapid build-up of ice, pitching the aircraft nose down and probably disorientating the crew. Airspeed increased to 392 kts and the G loading was peaking at 3.21 G. The angle of bank was probably between 50° and 60°. Increasing torsional stress on the wing roots probably caused panels to buckle and separate. At an altitude of 6800 feet the wings and engines started to separate. Nine seconds later the remaining fuselage impacted the sea about vertically and at high speed.
Probable Cause:PROBABLE CAUSE: The TAIC accident investigation report did not contain a probable cause.
Loss of control
Follow-up / safety actions
Safety issues identified included after the accident include:
- the need for all pilots and operators to have a better understanding of aircraft icing
- the use of air reports to alert pilots to hazardous meteorological conditions
- the adequacy of aircraft, operator and CAA documentation to assist pilots encountering adverse weather conditions, particularly for IFR and night freight operators in icing conditions
- the adequacy of the installation, performance and capabilities of cockpit voice and flight data recorders
- the requirement for a suitable tracking device to be readily available to find underwater location beacons.
This map shows the airport of departure and the intended destination of the flight. The line between the airports does not
display the exact flight path.
Distance from Christchurch International Airport to Palmerston North Airport as the crow flies is 434 km (271 miles).