The United States National Transportation Safety Board has determined that an air traffic controller who was distracted by a personal phone call played a critical role in the 2009 crash of a small plane and a sightseeing helicopter over the Hudson River.

In a meeting on Sept. 14, the NTSB said the probable cause of the accident was the controller’s distraction, combined with the inherent limitations of the “see and avoid” concept of collision avoidance. Contributing to the accident were the failure of both pilots to make effective use of their traffic advisory systems (TAS), inadequate air traffic control (ATC) procedures for handing off traffic near the Hudson River corridor, and U.S. Federal Aviation Administration regulations that did not ensure adequate vertical clearance between aircraft operating in the area.

 

The collision occurred on Aug. 8, 2009, when a single-engine Piper PA-32 Saratoga impacted a Eurocopter AS 350 helicopter operated by Liberty Helicopters. All nine people aboard the two aircraft were killed in the collision, which the NTSB concluded was “not survivable.” The plane, which had departed from New Jersey’s Teterboro Airport, was transiting the area en route to Ocean City, N.J. The helicopter had lifted off from a heliport on Manhattan’s West Side, and was approximately one minute into a sightseeing tour at the time of impact.

At the meeting, NTSB staff played an animation of the accident sequence of events (available online at http://www.ntsb.gov/events/2010/Hoboken-NJ/AnimationDescription.htm). As depicted in the animation, the airplane was out of the helicopter pilot’s field of view for the 32 seconds immediately preceding the crash. Although the helicopter would have been in the airplane pilot’s field of view during that time, the NTSB concluded that the helicopter would have been difficult to detect against a complex background of buildings. Although both pilots likely received warnings of the impending collision from their electronic TAS, neither appeared to have made effective use of them.

However, the NTSB was harshest on the Teterboro Airport local controller, who fielded a non-pertinent personal phone call in the minutes immediately preceding the accident. In accordance with NTSB policy, the content of the conversation was not made public. It was described by NTSB staff as a “jovial, relaxed, easygoing conversation” that could have been perceived by some as offensive and graphic. The Teterboro controller did not provide continual traffic advisories to the airplane pilot, and he unnecessarily delayed transferring communications for the accident airplane from Teterboro to Newark Liberty International Airport. The Teterboro controller also did not correct the airplane pilot’s incorrect read-back of the Newark tower frequency, which resulted in the airplane pilot going out of communication until the accident occurred. A timely handover to the correct frequency could have allowed the Newark controller to direct the airplane pilot to climb and turn away from traffic.

The investigation revealed that the accident occurred at an altitude of 1,100 feet, meaning the helicopter was slightly above the standard altitude of 1,000 feet mandated for its route of flight. Board member Mark Rosekind proposed an amendment to the NTSB’s report that would have listed this altitude deviation as a contributing factor to the crash. “Even if we can explain it away, those policies and procedures are in place for a reason,” he said, arguing that the commercial tour operator should have been held to a higher standard of professionalism. 

NTSB chair Deborah Hersman concurred with Rosekind, “I don’t think 100 feet is a lot, but I think in this environment it’s significant.”

Board member Robert Sumwalt, however, opposed the amendment vigorously. “A barometric altimeter is not a precision instrument,” he said, also arguing that 100 feet of altitude is considered an acceptable tolerance on many flight checkrides. It was further noted by NTSB staff that the pilot could have had an unknown operational reason for flying at the slightly higher altitude, such as bird avoidance. The amendment was eventually defeated.

The NTSB made five new recommendations as a result of its investigation. Those were: 1) redefining the boundaries of the East River common traffic advisory frequency (CTAF) so the Downtown Manhattan Heliport is in the area that uses the Hudson River CTAF; 2) mandating specific altitudes for the Hudson River special flight rules area; 3) updating the FAA’s advisory circular concerning collision avoidance (AC 90-48C); 4) developing standards for helicopter cockpit electronic TAS that address the unique operating characteristics of helicopters (this supersedes Safety Recommendation A-09-04); and once those TAS standards are developed, 5) requiring operators of electronic news gathering and air tour helicopters, as well as other operators using helicopters for passenger revenue flights, to install this equipment on their aircraft (this supersedes Safety Recommendation A-09-05).

Hersman noted that the FAA has responded swiftly after the accident to address immediate safety concerns (see p. 92, Vertical, Feb-Mar 2010). “The good news,” she said, “is that many important changes have already taken place.”