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| Date: | Friday 10 June 2022 |
| Time: | 10:47 |
| Type: |  Boeing 737-476 (SF) |
| Owner/operator: | Airwork |
| Registration: | ZK-TLJ |
| MSN: | 24432/1879 |
| Year of manufacture: | 1990 |
| Engine model: | CFMI CFM56-3 |
| Fatalities: | Fatalities: 0 / Occupants: 2 |
| Other fatalities: | 0 |
| Aircraft damage: | None |
| Category: | Incident |
| Location: | 167 km west of Meekatharra, WA -
 Australia
|
| Phase: | En route |
| Nature: | Cargo |
| Departure airport: | Perth Airport, WA (PER/YPPH) |
| Port Hedland Airport, WA (PHE/YPPD) | |
| Investigating agency: | ATSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
Airwork flight TFX13, a Boeing 737-476(SF), had taken off from Perth Airpor when the flight crew noted a 340 ft discrepancy between the captain’s and first officer’s altitude when operating in reduced vertical separation minimum airspace.
They had also observed an airspeed and Mach number difference, but this was within the manufacturer’s stipulated limits. The aircraft was descended, and the flight crew completed the Quick Reference Handbook - Airspeed Unreliable procedure. It was determined that the first officer’s instruments were reliable for a return to Perth. After landing, ground crews found foreign residue adhered to the lower surfaces of all 4 pitot-static probes.
The ATSB established that, during an engine ground run 2 days prior to the incident, the pitot‑static probe covers were not removed, and the automatic pitot heat was not isolated as required by the ground run procedures checklist. As a result, the covers melted onto the probes. Although cleaned, residue remained on the probe surfaces, which had the potential to compromise the accuracy of the pitot-static instruments in-flight. It was also established that pitot‑static probe covers made from polyvinyl chloride material were used, which increased the risk of the covers melting onto the probes if left on during engine operation.
Air traffic control were not advised of the altitude discrepancy of 340 ft, which exceeded the maximum allowed altimetry system error for reduced vertical separation minimum airspace of 200 ft. Therefore, adequate vertical separation with other aircraft could not be assured by air traffic control.
Accident investigation:
 |
|
Sources:
ATSB
https://www.flightradar24.com/data/aircraft/zk-tlj#2c2f6488
History of this aircraft
Other occurrences involving this aircraft
| 20 June 2022 | ZK-TLJ | Toll Aviation, opb Airwork | 0 | 167 km west of Meekatharra Airport, WA | |
non |
Revision history:
| Date/time | Contributor | Updates |
|---|---|---|
| 13-Apr-2023 09:34 | harro | Added |
Corrections or additions? ... Edit this accident description
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