Airlines PNG modifies its Dash 8 aircraft after fatal plane crash in Madang in 2011

Airlines PNG has modified its Dash 8 aircraft so pilots are unable to make the mistake that caused a fatal plane crash in Papua New Guinea three years ago.

The company has acknowledged that pilot error contributed to the accident in Morobe Province but says other factors were also at play.

Twenty-eight people were killed when a Dash 8 aircraft crashed near Madang in 2011.

The Australian and New Zealand pilots, a crew member and one passenger survived the accident.

The Accident Investigation Commission's final report found the pilot damaged the plane's engines on descent by putting them into reverse after an alarm sounded warning that the plane had reached its maximum speed.

Airline PNG's general manager of safety Craig Chapple told Pacific Beat the mistake had been made by several other Dash 8 pilots elsewhere in the world.

He says the crash would not have happened if Transport Canada, the regulating authority for the plane's manufacturer, had adopted previous recommendations to require 'beta lockout' devices to be installed to stop accidental reversing while a plane is in flight.

"There was a propeller control unit on the right-hand side that didn't work as required and allowed the right-hand engine into overspeed," he said.

"And then after the pilot had pulled the controls through the beta gate, he wasn't able to recover it on the left-hand side, the engine."

The Dash 8 was being flown manually because the aircraft's yaw damper was unserviceable.

In its report, the Commission found neither pilot noticed the aircraft's speed increasing to its maximum operating speed.

Mr Chapple says it is now not possible to put power levers into reverse on any Airlines PNG Dash 8.

"With the beta lockout modifications that we've done to the fleet, you cannot put the aircraft into beta in the air," he said.

"To go into reverse prior to the accident, you needed to lift the gate to go through the power levers into the beta range.

"They've obviously lifted the gate to go into the beta range by accident while they were dealing with the descent."

The Commission's Report found that once the Dash 8 was in trouble, the crew did not follow company procedures, such as extending the flaps or putting down the landing gear so the aircraft would have more time in the air and to soften the impact when it crashed.

"The crew at the time were obviously dealing with multiple critical events and there was other conflicting events occurring that were all high priority so they were in a high-stress environment," Mr Chapple said.

He says the pilots originally planned to ditch into the sea and it was only at the last moment that they decided to try to land beside a creek bed.