Incident
Flight PR137 was a regular scheduled passenger flight from Manila to Bacolod. The aircraft departed Manila at 18:40 with the thrust reverser of engine No. 1 inoperative. At 19:20, the crew contacted Bacolod Approach Control and reported passing FL260 at 55 DME from Bacolod. After receiving landing instructions, the flight descended in stages, eventually being cleared for a visual approach and landing on Runway 04. The weather at the time included wind from 030° at 8 knots, an altimeter setting of 1014 mbar, a transition level at FL60, and a temperature of 28°C.
Approach and Landing
The approach was flown with the autothrust system engaged in SPEED mode, and the thrust lever of engine No. 1 was left in the climb detent. Upon touchdown, the first officer called out "no spoilers, no reverse, no decel." Engine No. 2 was set to full reverse thrust, but the No. 1 engine thrust lever was not retarded to idle and remained at climb power. This prevented the spoilers from deploying. When one engine was set to reverse, the autothrust system disengaged, and with the system disengaged, No. 1 engine thrust increased to climb thrust. The resulting asymmetrical thrust condition caused the aircraft to veer off the right side of the runway. At that speed, rudder and nosewheel steering were ineffective. Engine No. 2 was then moved out of reverse to more than 70% N1, causing the aircraft to swerve back onto the runway.
The aircraft continued beyond the runway end, struck the airport perimeter fence, jumped over a small river, and then went through a hollow block fence, several clusters of shanties, and trees. No fire ensued after the impact.
Probable Cause
The probable cause of this accident was the inability of the pilot flying to assess properly the situational condition of the aircraft immediately upon touch down with No. 1 engine reverse inoperative, thereby causing an adverse flight condition of extreme differential power application during the landing roll resulting in runway excursion and finally an overshoot. Contributory to this accident is the apparent lack of technical systems knowledge and lack of appreciation of the disastrous effects of misinterpreting provisions and requirements of a Minimum Equipment List (MEL).