Significant question marks over the use of old and scary jets by charter airline Oz Jet are apparent in preliminary air safety investigation reports into the carrier’s two headline making Christmas holiday emergencies.

On 29 December one of its 32-year-old Boeing 737-200s suffered a flap failure that saw passengers on a flight from Brisbane to Norfolk Island wearing their life vests in case the flight was forced to ditch into the ocean as it diverted to Noumea.

On 31 December another similarly aged Oz Jet 737-200 that had departed Port Moresby for Brisbane made a Mayday distress call and a quick return to the airport after a part of a crucial control surface near its tail broke off.

The Australian Transport Safety Bureau describes how the first flight experienced high frequency vibrations after flaps failed to retract properly when the pilots aborted an attempt to land at Norfolk Island in low cloud and driving rain.

The problem caused the jet to pull 40 degrees to the left of its intended course and suffer continued buffeting and roll and “yaw” (or nose wagging) for much of the diversion to Noumea, the nearest alternative airport.

Because of doubts about whether the jet would make Noumea, full emergency drills were carried out in the cabin with passengers putting on uninflated life vests and preparing for the worst.

In the Port Moresby incident, the ancient 737 suffered vibration so severe the pilots reported the jet was difficult to control. A section of the right elevator tab in the tail of the jet had broken off.

This component is of crucial importance to the controllability of all 737s old or new. The ATSB notes that Oz Jet had complied fully with a special service bulletin mandating close inspections of this part.

In both cases the safety investigator is now looking in more detail into how such old jets are serviced.

Its findings will have global relevance, as 737-200s are widely used by third world carriers because they can be cheaply acquired for close to scrap value. This model of the 737 figures disproportionately in crash statistics, particularly in Africa and Indonesia.

Oz Jet is sometimes described within the industry as having among the best of pilots and cabin crew but flying the worst of aircraft.