Originally Posted by
shimin
Firstly the QAR decoding showed the fleet repeated such an unofficial operation, unlock of ground idle throttle in air.
It sounds like the Power Level (PL) Lock was opened, allowing the power levers to go to ground idle whilst in the air. The FCOM calls for the PL lock to be closed when the aircraft is in the air thereby preventing the power levers to be retarded past flight idle in to ground idle and beta range. With PL lock closed, the power levers will not go in to beta range until the wheels are on the ground through a 'weight on wheels' (WOW) mechanism.
So, it sounds like a repeat of the MA60 incident in Kupang then, with the power levers going in to ground idle and possibly even in beta range due to the PL lock being opened. Crews sometimes deliberately set the PL lock to open because the WOW mechanism sometimes does not function correctly, and prevents the power levers to be retarded to beta for reverse thrust after landing.