What happened
During taxi operations at Hobart Airport, a Boeing 737, registration YFT, encountered insufficient clearance from an adjacent aircraft parked in a nearby bay. While maneuvering toward taxiway H, the flight crew stopped the aircraft. Upon restarting movement, the aircraft taxied across the lead-out line for approximately one to two seconds before initiating a right turn. During this period, the wingtip of YFT moved too close to the parked aircraft, which was an A320.
The investigation
The investigation examined the taxi path, the aircraft's positioning, and the airport's infrastructure. It was noted that the Boeing 737's nose wheels were initially inside the lead-out line, which typically suggests sufficient clearance. However, the investigation found that after the aircraft stopped, the pilot could no longer visually confirm the position of the lead-out line, as it had moved beneath and behind the cockpit. Furthermore, the lack of a continuous marked line connecting the lead-out line to taxiway H contributed to uncertainty regarding the aircraft's track.
Findings
- The design of the power-out bays at Hobart Airport provides very limited maneuvering room, making it difficult to maintain a continuous turn after stopping.
- The aircraft taxied outside the marked turning circle after stopping and without sufficient thrust or tiller input to maintain the turn.
- The pilot's view of the nose wheel's position relative to the taxi guidance line is difficult to maintain in a Boeing 737 because the nose wheel is laterally offset and positioned behind the flight deck.
- The parking bay design standards may not account for non-normal situations, such as an aircraft needing to stop mid-turn.
- There was an absence of documented procedures for flight or ground crews regarding aircraft that stop while crossing a lead-out line.
- The aircraft parked in the adjacent bay, an A320, was positioned with its tail slightly left of the centerline and aft of the stop mark, which reduced the available clearance.