Incident Overview
On May 1, 2013, at approximately 1924 Eastern Daylight Time, ExpressJet flight 4226, an Embraer E145 (N17560), was stationary on taxiway R at Newark Liberty International Airport (KEWR), Newark, New Jersey, when it was struck by the left wing of Scandinavian Airlines (SAS) flight 908, an Airbus A330 (LN-RKO). No injuries occurred to any passengers or crew aboard either aircraft. Flight 4226 sustained substantial damage, while flight 908 received minor damage. Both flights were operating as scheduled passenger services under 14 Code of Federal Regulations Part 121 and Part 129, respectively. Flight 4226 was destined for Nashville International Airport, Tennessee, and flight 908 for Oslo Airport, Norway.
Taxi and Positioning
Flight 4226 pushed back from the gate at 1857. After leaving the ramp area, its crew was instructed to hold short of taxiway Y on taxiway R, awaiting a Boeing 737 to pass from the left. They stopped on taxiway R facing northeast with the parking brake set.
Flight 908 pushed back at 1901 with an additional check pilot in the cockpit jumpseat to supervise the new first officer. After leaving the gate, it was initially cleared to taxi northbound on taxiway R and hold short of taxiway Y. The crew received subsequent instructions to turn left onto taxiway M, then right onto taxiway M, then cross runway 22R on taxiway Y, and turn left onto taxiway P to hold short of runway 22R on the east side.
Collision and Crew Accounts
Flight 908's crew observed flight 4226 but noted the low sun on the horizon made visibility difficult. They also monitored runway 22R for conflicting traffic. The crew estimated their wing would clear flight 4226. As flight 908 turned onto taxiway M, its winglet contacted the tail section of flight 4226. The crew did not feel the impact and were unaware of the collision until informed after crossing runway 22R.
Flight 4226's crew did not see flight 908 pass behind them but felt the impact. They shut down engines and were towed back to the gate after a safety evaluation.
Aircraft Dimensions and Taxiway Geometry
Flight 4226 had a wingspan of 65 feet 9 inches, length 98 feet, horizontal stabilizer width 22 feet 2 inches, and vertical stabilizer length 24 feet 9 inches. Flight 908's wingspan was 197 feet 10 inches. Newark's taxiways were nominally 75 feet wide with centerline and edge markings. No markers or indicators provided guidance for traffic clearance on intersecting taxiways, nor were they required.
The distance between the centerlines of taxiway Y and taxiway M was about 487 feet. Flight 4226 was instructed to hold short of taxiway Y within that area to give way to a Boeing 737. A B737's wingspan is about 113 feet, projecting approximately 56.5 feet from the taxiway Y centerline, with about 19 feet extending onto taxiway R. No hold short lines or guidance indicators existed on taxiway R to ensure wingtip clearance from passing aircraft on taxiway Y or M, nor were they required.
Pilot Actions and Manuals
In a follow-up statement, flight 908's captain said he watched his winglet relative to flight 4226's wingtip but did not see the other aircraft's tail, which was struck. The crew stated that after determining they would clear flight 4226, they focused on the active runway crossing procedure.
A review of SAS manuals found no specific training, guidance, or procedures for ensuring wingtip clearance during ground operations. The manuals indicated that, aside from ramps or aprons with external guidance, taxiing past obstructions should only be attempted if the separation distance exceeded one-quarter of the aircraft's wing span (49.2 feet for the A330). Additional SAS information noted that seeing the A330's wingtips from the cockpit required "moving close to the side window and turning the torso backwards."
The manuals described techniques for taxiing on centerline but offered no guidance for ensuring wingtip clearance during straight taxi or turns. The operations manual stated that when in doubt, request assistance from ATC. The SAS A330/A340 Flight Crew Training Manual described "judgmental oversteering" to keep main landing gear on paved surfaces during turns, a technique gained with experience.
Previous NTSB Recommendations
Following twelve wingtip collision investigations since 1993, the NTSB issued Safety Recommendations A-12-38 and A-12-49, highlighting the need for anti-collision aids (e.g., camera systems) to help pilots determine wingtip clearance during taxi. The recommendations covered new and existing large aircraft where wingtips were not easily visible from the cockpit. The FAA responded that the recommendations did not justify the cost burden of a mandate, classifying them as "closed - unacceptable." Flight 908 had no such anti-collision aid installed.