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On March 22, 2008, about 1110 eastern daylight time, the tail skid of an Aerospatiale AS355F1, N406LH, contacted the low turning main rotor of a parked Eurocopter EC130B4, N456AE, when the Aerospatiale was departing the West 30th Street Heliport (JRA), New York, New York. Both helicopters were operated by Liberty Helicopters. The pilot and the four passengers on board the Aerospatiale, and the pilot on board the Eurocopter, were not injured. The sightseeing flight was being operated under the provisions of 14 Code of Federal Regulations Part 135. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed.
The Aerospatiale was parked on helipad number seven, and the Eurocopter was in the adjacent spot to the right, on helipad number six. Both helicopters faced southeast, with their tails pointed towards the Hudson River. On departure, the pilot of the Aerospatiale initially "picked up to a hover." He then focused his attention on the torque gauges, and "proceeded to a higher hover." The pilot turned the Aerospatiale to the left, and heard a "small thud." He landed the helicopter back on helipad seven, and completed an engine shut down.
The airline transport pilot, age 33, held an airline transport pilot certificate with a rating for rotorcraft helicopter. In addition, he held a flight instructor certificate with ratings for rotorcraft helicopter and instrument helicopter, and a private pilot certificate with ratings for airplane single engine land. The pilot had 5,130 total flight hours, of which 5,100 hours were in rotorcraft, including 4,800 hours as pilot in command. The pilot reported that he had about 10 hours in the AS355 twin engine helicopter, and about 250 hours in the AS350 single engine helicopter. His most flight review was on March 6, 2008, and his most recent FAA first-class medical certificate was issued in October 2007.
The Aerospatiale AS355F1 was a six-place helicopter, powered by two turbine engines. The helicopter was equipped with a three-bladed composite main rotor system approximately 35 feet in diameter, and a conventional tail rotor system located about 26 feet aft of the pilot's station. The most recent 100-hour inspection was conducted on March 22, 2008. As of the date of the accident, the airframe had accumulated a total of 7,393 hours in service.
The Eurocopter was not being operated for the purpose of flight at the time of the collision. The Eurocopter had a main rotor diameter of approximately 35 feet, and an overall length of approximately 42 feet.
The New York City, New York 1051 surface weather observation, located 3 miles northeast of JRA, reported winds from 290 degrees at 7 knots, visibility 10 miles, few clouds at 8,500 feet, temperature 5 degrees Celsius (C), dew point minus 17 degrees C, and altimeter setting of 29.94 inches of mercury.
The JRA heliport was situated on the east shore of the Hudson River in Manhattan. The primary landing area measured approximately 300 feet by 50 feet, with the long dimension aligned on a true heading of 030 degrees. A land-based touchdown and lift off (TLOF) area included five helipads that were designated by painted circles, and that were designated as helipads three through seven. Helipad seven was the northernmost of these circles, and helipad six was adjacent to helipad seven. The circles for helipads six and seven were 37 feet in diameter. The distance between their centers was approximately 50 feet, and there was approximately 14 feet between their perimeters. The landing and initial departure orientation of helicopters using these helipads was 120 degrees true.
A water-based TLOF area was situated on a barge anchored perpendicular to, and 20 feet north of, the northern end of the land-based TLOF area. The barge extended approximately 270 feet into the river, and contained 4 additional helipads.
The offices for the operators at the heliport formed an "L" at the northeast corner of the heliport. The northern leg of the "L" was 40 feet from the center, or 21 feet from the perimeter, of helipad seven. The eastern leg of the "L" was 27 feet from the center, or 8 feet from the perimeter, of helipad seven.
According to the pilots, the operator based its helicopters at an airport in New Jersey, and rarely shut down its helicopters when they were on the helipads at JRA. Neither the heliport nor the operator employed marshallers to provide assistance to pilots for arrivals or departures.
WRECKAGE AND IMPACT INFORMATION
Post-shutdown inspection revealed that the tailskid of the Aerospatiale was separated from the lower vertical stabilizer, and that a portion of the tail rotor guard had been severed by its contact with the main rotor blades of the Eurocopter. Detailed inspections did not detect any additional damage to the Aerospatiale. One of the three main rotor blades of the Eurocopter sustained substantial damage.
According to FAA Advisory Circular (AC) 150/5390-2B, Heliport Design, the document "provides recommendations for heliport design and describes acceptable requirements to develop a heliport" and "applies to anyone who is proposing to construct, activate or deactivate a heliport." The AC stated that it "is not mandatory and does not constitute a regulation except when Federal funds are specifically dedicated for heliport construction."
The AC recommended three minimum helipad area dimensions, and one helipad separation dimension, that were a function of the rotor diameter and the overall length of the helicopter using the helipad. The three areas were concentrically arrayed, and in increasing size order were the TLOF, the Final Approach and Takeoff Area (FATO), and the Safety Area. The AC defined helicopter Overall Length (OL) as "the distance from the tip of the main or forward rotor to the tip of the tail rotor or fin. This measurement is made with the rotors at their maximum extension." The AC defined the Final Approach and Takeoff Area (FATO) as a "defined area over which the final phase of the approach to a hover, or a landing is completed and from which the takeoff is initiated."
Paragraph 201b of the AC stated that "the minimum TLOF dimension (length, width, or diameter) should be 1.0 times the rotor diameter (RD) of the design helicopter." Paragraph 202b stated that "the minimum width, length or diameter of a FATO should be at least 1.5 times the overall length (OL) of the design helicopter," and that "the minimum distance between the TLOF perimeter and the FATO perimeter should be not less than the distance [0.5 x (1.5 OL - 1RD)] where OL is the overall length and RD is the rotor diameter of the design helicopter."
Paragraph 202e stated that "If a heliport has more than one FATO, the separation between the perimeters of the two FATO, should be such that the respective Safety Areas do not overlap," Paragraph 203 stated that a "Safety Area surrounds a FATO and should be cleared of all obstacles except small frangible objects that, because of their function, must be located there," and specified a minimum safety area width of 20 feet. The AC recommended a minimum distance between helipads such that their respective safety areas did not overlap.
Calculations that used the Aerospatiale AS355F1 rotor diameter of 35 feet, and overall length of 42 feet, resulted in a minimum TLOF diameter of 35 feet, a minimum FATO diameter of 63 feet, a minimum distance between the TLOF perimeter and the FATO perimeter of 14 feet, and a minimum safety area diameter of 103 feet. The 37 foot-diameter TLOF marking was present for the two subject helipads, and the diameters were in compliance with the AC.
No FATO or safety area markings were present for the two subject helipads, and the spacing between them did not comply with the other minimum dimensions specified by the AC noted above. A distance of 103 feet, instead of the existing 50-foot separation between the helipad centers, was required to enable compliance with the minimum TLOF, FATO and safety area dimensions and helipad separation criteria specified by the AC.