NTSB seeks traffic cameras on large airliners
In making its recommendation, the agency cited three recent accidents.
Safety board officials told the Federal Aviation Administration that equipping planes with anti-ground-collision warning devices such as externally mounted cameras is a common-sense approach that has been embraced by automobile manufacturers, which offer cars with sensors to detect when other vehicles are in a driver's blind spots and rear-mounted cameras to assist while backing up.
The safety board recommended that the FAA require cameras on new large commercial planes and that the existing fleets be retrofitted with cameras too.
"While collision warning systems are now common in highway vehicles, it is important for the aviation industry to consider their application in large aircraft," NTSB Chairwoman Deborah Hersman said.
The FAA said it would review the recommendation to require cameras on large commercial airliners, including Boeing 747, 757, 767 and 777 aircraft; Airbus A380; and McDonnell Douglas MD-10 and MD-11.
Airlines for America, the airline industry trade group, expressed concern about the unknown cost of installing cameras on planes.
"These types of incidents (ground collisions) are extremely rare in the context of overall operations. We are not aware of any passenger injuries from these types of incidents," said Jean Medina, a spokeswoman for Airlines for America.
In a letter to the FAA, the safety board said it has investigated 12 accidents since 1993 that occurred during taxiing when a large plane's wingtip hit another plane or object on the taxiway.
Collisions while planes are taxiing to runways or parking ramps or being pushed back from gates -- typically involving wingtips of large planes striking wingtips or tail sections of other aircraft or jet bridges, poles or ground vehicles -- have been a problem in the airline industry for years, experts said.
In addition to their main function of providing lift, wings contain tanks that store thousands of pounds of fuel.
The wingspan of a Boeing 747-400, which is the type of one of the aircraft involved in the O'Hare collision, is 211 feet 5 inches. A 747 pilot cannot see the airplane's wingtips without opening the cockpit window and sticking his or her head outside, which is often impractical. So pilots must determine wingtip clearance and the safest path relying mainly on judgment, officials said.
Flight crews' failure to maintain sufficient clearance from other aircraft is the leading cause of taxiing accidents, according to a Chicago Tribune review of more than 25 ground collisions between air carriers at U.S. airports that the NTSB has investigated since 2004. Other factors included errors made by ground crews marshalling aircraft around terminals and airplane tug operators, the accident reports reveal.
Some of the accidents occurred while planes were being pushed back from nearby gates simultaneously, or in locations at the tips of concourses where gates were previously banned but added over the years, in close proximity to taxiways, to increase parking capacity.
The number of taxiing accidents have been significantly reduced from several hundred annually to less than a dozen, officials said, thanks to preventive measures: the introduction years ago of ground crews called "wing walkers" who escort planes into and out of parking areas outside terminals, improved pilot taxi chart instructions, and stronger pavement markings.
But the growing mix of jumbo jets and small regional jets on increasingly congested airfields worries safety officials. All three recent accidents, at Chicago O'Hare International Airport, Boston Logan International Airport and Kennedy International Airport in New York involved large jets and commuter-style planes. The pilots of the large planes could not easily view the airplanes' wingtips from the cockpit, according to preliminary information from all three accidents, NTSB investigators found.
In an April 2011 accident at Kennedy, a wing on an Air France A380, which is the world's largest commercial airliner, clipped the tail of a small Comair Delta Connection regional jet while taxiing. The impact lifted and spun the smaller plane 90 degrees. Video showed that the tail of the smaller plane, which was heading toward a gate, was hanging over a taxiway when it was hit. There were no injuries.
The 555-seat A380 - equipped with exterior cameras on the belly and vertical tail fin of the fuselage and an external landscape camera, but no cameras showing the airplane's wingtips-has a wingspread spreading almost 262 feet, nearly the length of a football field.
A separate collision in Boston also under NTSB investigation involved a Delta Air Lines Boeing 767 that was taxiing for departure when its left winglet struck the horizontal tail of an Atlantic Southeast Airlines regional jet that was in front of the larger plane.
No injuries were reported in the three incidents.
Although low-speed taxiing collisions do not pose the biggest aviation danger from a fatality standpoint, there is the potential for deadly outcomes from accidents because wings contain storage tanks for jet fuel, officials said.
"Most taxiing ground collisions are like a fender-bender in a parking lot with your car - usually not catastrophic, but expensive to airlines and an inconvenience to passengers" because the planes involved sustain damage that usually takes them out of service, said John Cox, a former US Airways captain who is now an aviation safety consultant.
"Still, we need to focus on these incidents of lesser consequence so they don't become high-risk," Cox said.
The O'Hare incident occurred on May 30 when the right wingtip of a Boeing 747 cargo plane operated by EVA Air was taxiing and struck the rudder and vertical stabilizer of an American Eagle Embraer 135 regional jet, according to the NTSB, which is investigating the accident.
The Eagle plane was taxiing to the ramp area and waiting for a ground crew to guide it to gate G20, which is at the end of the G Concourse where Eagle gates are tightly spaced near busy Taxiway A. The tail section of the plane was protruding into Taxiway A, according to the ongoing NTSB investigation.
The EVA Air 747 was taxiing westbound on Taxiway A when its right wingtip struck the Eagle's rudder and vertical stabilizer, the preliminary investigation report said.
Veteran air-traffic controllers at O'Hare said they opposed airline plans years ago to add gates at the ends of concourses that are like fingertips because of concerns that planes being pushed back from gates could hit other planes on the nearby taxiway.
"It is like pushing a 40-ton truck backwards down a ramp onto the Kennedy Expressway," O'Hare controller Craig Burzych said. "The airlines generally do a good job pushing back, but there is still a potential for a collision. And in a lot of situations it's hard for us to see from our angle in the control tower whether they cleared the taxiway."
The safety concerns haven't stopped the airlines from adding gates. United Airlines is spending $13 million to build 10 jet bridges to load passengers at United Express gates in the F Concourse of Terminal 2. Seven of the 10 gates are at the end of the concourse. The work began in May and is scheduled for completion in mid-2013, the airline said.
Megan McCarthy, a United spokeswoman, said the new bridges are fully certified and are being constructed in areas where United Express planes have parked for many years, using portable stairs to board and deplane passengers.
"We have standard operating procedures in place for our employees to ensure safe operation of our aircraft when parking and pushing back," McCarthy said.
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