The entrance to the engine compartment is 48cm by 30 cm. Participants are to crawl on their side, five metres into the intake before crawling backwards in the game gap.
The activity on April 24, 2009, was part of team bonding games during the informal welcome ceremony for new or promoted staff at the Paya Lebar Air Base.
The tunnel crawl is considered a tradition during such ceremonies.
The court was told that 2WO Poh wars seen slouching on a sofa in the crew room at about 6pm. He looked pale and his head was tilted backwards.
When his colleagues failed to rouse him, they tried for 40 minutes to resuscitate him but he could not be revived.