Thursday, April 14, 2011

A history of strife: Jumbo wingtips and regional stabilizers

A history of strife: Jumbo wingtips and regional stabilizers: "

Monday night's incident at John F. Kennedy International Airport, which featured the wingtip of an Air France A380 catching the horizontal stabilizer of a Delta CRJ700, has been broadcast widely, eliciting gasps and groans with the sight of the regional jet's rapid 90-degree change of heading. The event has elicited calls to re-evaluate whether or not the A380 is too big to operate at congested airports - ironic as congested airports central to the aircraft's business model - but while the historical context has largely been limited to reminders of the 1977 Tenerife accident, a far more recent example involving a jumbo and a regional jet offers some context.

In July 2006 the wingtip of a Thai Airways Boeing 747-400 in Madrid severed the stabilizer of an Air France RĂ©gional EMB-135 (full description of the incident) after the 747 inadvertently used a taxiway designed for aircraft no larger than Airbus A321s. The pictures of the aftermath are below.

The incident, which was not caught on video, didn't happen in the US, but did involve the world's largest commercial aircraft at the time did not elicit the same type of calls for a re-evaluation of using large aircraft at busy airports. This was likely because the taxiway was wasn't intended for use by a 747 at the time, whereas taxiway A at JFK has been deemed A380 compliant.

While the size of the aircraft was - for obvious reasons - a contributing factor in both incidents, the issue appears to be more related to situational awareness about the goings-on around an airport's taxiways and tarmacs.

The A380, 787 and 747-8 all feature airport moving maps on the flight deck with aircraft-centric displays directly integrated into the primary navigation displays and electronic flight bags. On Airbus aircraft the system is dubbed the Onboard Airport Navigation System (OANS) and the Airport Moving Map (AMM) for Boeing aircraft.

United Airlines Boeing 787 Dreamliner CAE Simulator
A380-OANS2.jpgMissing from both OANS and AMM is the capability to display the position of other airport traffic providing a broad situational awareness for the crew on the flight deck. According to a feature in this quarter's Aero, Boeing's technical magazine, the airframer sees a possible 2015 availability for harnessing precision GPS-derived position data ADS-B to display nearby aircraft on the AMM.

While there's a natural tendency to overreact to an incident involving the largest commercial aircraft in the world striking a smaller regional jet at one of the planet's busiest airports, a more reasoned incremental approach to solving the problem with technology will enable the best long-term solution.

As air traffic worldwide continues to grow at a pace of 5% per year, airport infrastructure hasn't been able to keep pace as congestion grows. A common refrain at this week's MRO Americas conference was that as air traffic doubles over the next two decade, incidents and accidents cannot double as well.

Jumbo jets have been with us for more than 40 years and wingtips large and small will infrequently make contact with objects providing a large-scale example of Newton's laws of motion. This likely won't change, though with the right technology, the frequency certainly can as aviation continues its worldwide growth.

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