What happened
Northwest Flight 78, operated by a Boeing 757, was parked at Gate 17 facing east. A mobile passenger lounge (MPL) was docked at the L1 door of the aircraft. Northwest had recently replaced its previous DC-10 with this 757, which normally deplanes passengers through the L1 door. However, Flight 78's arrival was delayed that day, so deplaning was still in progress when United Flight 52 arrived.
United Flight 52, a DC-10, taxied in an easterly direction along the left side of Northwest Flight 78. The aircraft then turned right to follow a southeasterly heading toward Gate 15. United had recently begun using Gate 15 for DC-10 operations. While on the lead-in line, with its nosewheel positioned approximately 3 to 6 feet to the right of the designated line and following signals from a guideman, the right wingtip of the DC-10 struck the aft end of the mobile passenger lounge.
The driver of the MPL was standing on the gangway at the time of impact. The force of the collision caused the driver to fall backward into the Northwest 757, resulting in minor injuries. Both aircraft sustained minor damage, while the mobile passenger lounge suffered substantial damage.
The investigation
Investigators conducted measurements to assess the spatial relationship between the aircraft and ground equipment at the gate area. These measurements confirmed that insufficient clearance existed for a DC-10 to safely occupy Gate 15 when a mobile passenger lounge was docked with a Boeing 757 at the adjacent Gate 17.
Findings
The incident highlighted operational challenges arising from recent changes in aircraft types and gate assignments. The substitution of a DC-10 with a Boeing 757 for Northwest Flight 78 altered the deplaning configuration, keeping the mobile passenger lounge docked longer than usual. Simultaneously, United's introduction of DC-10s to Gate 15 created a tight spatial constraint that was not adequately accounted for during taxi operations.