Mistakes Led Planes Toward Near-Collision
January 8, 2011
By ANDY PASZTOR
The National Transportation Safety Board said a series of slip-ups by pilots and air-traffic controllers twice put a US Airways Group Inc. jet and a Boeing 747 cargo plane on a near-collision course over Alaska last year.
Communication lapses by both sets of pilots, compounded by lax controller procedures, temporarily cut off radio contact between the relevant controller and the planes.
The board's report on the May incident, released earlier this week, indicates that the US Airways plane with 138 people aboard ended up flying 100 feet under the altitude of the Cargolux cargo jet. The planes were separated by less than one-third of a mile horizontally, as they maneuvered in good weather near the international airport in Anchorage, Alaska.
The report comes amid heightened concerns about reported controller errors nationwide, which have increased recently and last year prompted the Federal Aviation Administration to launch various safety initiatives. The safety board also has stepped up its scrutiny of midair near-collisions.
In the May incident, the US Airways Airbus A319 arriving from Phoenix encountered a wind shift and its crew decided to break off the landing approach and climb away from the airport. At the same time, the larger cargo plane was departing from a different runway. According to the safety board, misunderstandings between controllers and lax communication procedures by both cockpit crews resulted in the flight paths of the two planes converging twice during the incident.
The board found that the controller monitoring the A319's progress failed to keep proper track of its speed and direction, and didn't coordinate with another controller handling takeoffs and landings. The second controller tried but failed to contact the planes about the impending conflict, but both crews were tuned into another radio frequency.
After the A319 pilots had the cargo jet in sight, they failed to acknowledge instructions to maintain visual separation. Once again, controller instructions led the flight paths of the two planes converge.
The board's report indicates that a collision was avoided because the pilot flying the A319 temporarily stopped the controller-ordered turn and then heeded an onboard emergency collision-avoidance warning to descend.
Separately, the FAA on Friday released final safety mandates for many older Boeing 757 and 737 models, covering enhanced structural inspections of more than 1,300 jetliners. The rules, made public by the FAA, are designed to prevent hazardous fuselage cracks that could result in reduced structural integrity and rapid aircraft decompression.
Boeing previously issued nonbinding safety bulletins covering both widely used models. The mandatory FAA rules—slated go into effect in the next few weeks—cover more than 630 older 737 models and an additional 680 older 757s.
The 757 rule was prompted by a sudden rupture and decompression suffered by an American Airlines 757 on a flight from Miami to Boston in October. Nobody was hurt, and the AMR Corp. unit's plane returned safely to Miami, despite a one-foot tear in its aluminum skin. But the FAA's mandate, which the agency considers "interim action" pending further moves to resolve underlying safety issues, entails repetitive inspections ranging between 30 and 300 flights.
The 737 rule calls for certain structural checks ranging from every 3,000 to 4,500 flights, and it also spells out a repair that would terminate such repetitive inspections.
Write to Andy Pasztor at firstname.lastname@example.org