Description

On August 8, 2009 a privately operated PIPER PA32-260 Cherokee Six and a Eurocopter AS350BA helicopter being operated by Liberty Helicopters on a public transport sightseeing flight collided in Visual Meteorological Conditions (VMC) over the Hudson River near Hoboken, New Jersey whilst both operating under Visual Flight Rules (VFR). The three occupants of the PA32, which was en route from Wings Field PA to Ocean City NJ, and the six occupants of the helicopter, which had just left the West 30th Street Heliport, were killed and both aircraft were destroyed.

Investigation

An investigation was carried out by the National Transportation Safety Board (USA) (NTSB). It was established that both aircraft had been operating VFR and heading south along the river. Radar data showed that the collision had occurred at an altitude of approximately 1100 feet and a groundspeed of about 150 knots for the airplane and about 93 knots for the helicopter. The position and estimated altitude implied a position at the boundary of Class 'E' airspace up to 1100ft and Class 'B' aispace above this, with neither aircraft having sought ATC clearance to clinmb above 1100 feet. After the impact, both aircraft fell into the Hudson River below. The radar data also showed that in the minute prior to the collision, a conflict alert for the PA32 and the accident helicopter was generated 11 times to both the low level and higher level ATS Units, bur neither controller recalled seeing or hearing such an alert on their radar display during that time. The collision was witnessed by numerous people, some of whom indicated that neither aircraft appeared to conduct any avoidance manoeuvre prior to the collision. A private video appeared to show the PA32 rolling right just before the collision. The diagram of the tracks of the accident aircraft are shown on the diagram below taken from the official accident report:

During the early stages of the Investigation, on 27 August 2010, the NTSB issued 5 Safety Recommendations to the Federal Aviation Administration (FAA) in respect of the management of the low level Hudson River airspace and the response and actions to these, including the establishment of Special Rules Airspace, are detailed in the Final Report.

The Investigation found that weather was not a factor in this accident, and sun glare would not have interfered with the pilots’ abilities to detect and track the conflicting aircraft.

Other findings of the Investigation included extensive criticism of aspects of the air traffic service provided to the fixed wing aircraft involved in the collision. It was also noted that:

• the helicopter’s climb above 1,000 feet was not consistent with the operator’s procedures and decreased the vertical separation between the aircraft.
• neither pilot effectively used available electronic traffic information to assist in maintaining awareness of nearby aircraft.
• current FAA regulations do not provide adequate vertical separation for aircraft operating in the Hudson River special flight rules area because the regulations do not include specific operating altitudes for local aircraft.
• the guidance in Advisory Circular (AC) 90-48C, “Pilots’ Role in Collision Avoidance,” could better assist pilots’ efforts to establish effective see-and-avoid skills if the AC were to recognize current challenges that pilots encounter in managing their see-and-avoid responsibilities, including complex, high-density airspace and the increasing presence of technology in the cockpit.
• because the FAA’s current TSOs for electronic traffic advisory systems do not distinguish between the different flight characteristics of helicopters and fixed-wing airplanes, the effectiveness of these systems aboard helicopters is limited.
• the traffic alerting function of helicopter electronic traffic advisory systems is limited because the parameters used to trigger alerts do not consider frequent maneuvering in congested areas, resulting in nuisance alerts.
• electronic traffic advisory systems installed on helicopters operated for passenger revenue flight would enhance a pilot’s capability to detect other aircraft operating in the same area by providing aural annunciations and visual displays of the traffic.

Five Safety Recommendations were made at the conclusion of the Investigation all to the FAA to the effect that it should:

• Redefine the boundaries of the East River common traffic advisory frequency (CTAF) so that the Downtown Manhattan Heliport will be located in the area that uses the Hudson River CTAF. (A-10-124)
• Revise 14 Code of Federal Regulations 93.352 to specify altitudes of use for aircraft conducting local operations in the Hudson River special flight rules area so that the regulation includes required operating altitudes for both local and transiting aircraft, and incorporate the altitude information for local operations onto published visual flight rules aeronautical charts for the area. (A-10-125)
• Update Advisory Circular 90-48C to reflect current-day operations, including (1) a description of the current National Airspace System and airspace classifications, (2) references to air tour operational areas as high-volume traffic environments, and (3) guidance on the use of electronic traffic advisory systems for pilots operating under the see-and-avoid concept. (A-10-126)
• Develop standards for helicopter cockpit electronic traffic advisory systems that (1) address, among other flight characteristics, the capability of helicopters to hover and to fly near other aircraft at lower altitudes, slower airspeeds, and different attitudes than fixed-wing airplanes; (2) reduce nuisance alerts when nearby aircraft enter the systems’ alerting envelope; and (3) consider the different types of operations conducted by helicopters, including those in congested airspace. (A-10-127)
• Once standards for helicopter electronic traffic advisory systems are developed, as requested in Safety Recommendation A-10-127, require electronic news gathering operators, air tour operators, and other operators of helicopters used for passenger revenue flight to install this equipment on their aircraft. (A-10-128)

The Final Report of the Investigation was adopted by the NTSB on 14 Sept 2010 and may be seen in full at SKYbrary bookshelf: NTSB/AAR-10/05

Further Reading

• See and Avoid
• Collision Avoidance
• Loss of Separation - Pilot-induced Situations
• Traffic Information
• Radar Information Service
• Radar Advisory Service
• Radar Control Service