What happened
While taxiing for takeoff, an aircraft was part of a line of 10 aircraft cleared by ATC ground control to proceed. The movement of the line was intermittent, with the aircraft moving and stopping repeatedly over a period of approximately 20 to 30 minutes.
During one of these stops, the aircraft began to creep forward toward the preceding aircraft without the pilot realizing it. This movement continued until the right engine propeller struck the tail of the leading aircraft. The collision resulted in substantial damage to both aircraft involved. At the time of the impact, the captain was at the controls but could not recall what had been occupying his attention immediately prior to the event.
The investigation
A post-accident examination of the aircraft was conducted, which failed to reveal any malfunction of the brake system.