Helipad Harmonization Redux

By John Croft | June 1, 2005

This month international officials launch the latest effort to make sense of the hodgepodge of helicopter landing-site design standards.

A three-year effort to retool global design standards for helicopter landing and takeoff facilities and their surrounding airspace will get a jolt in June when a new International Civil Aviation Organization (ICAO) design standards group picks up where its predecessor left off last year. As with the earlier effort, the Helipad Design Working Group's primary goal will be to harmonize ICAO regulations with the hodgepodge of standards or practices used by various member countries when it comes to helipad or helideck (an offshore helipad) size and the shape of the surrounding airspace.

ICAO last fall disbanded its ad hoc study group comprised of more than a dozen representatives from various member nations who had delved into the issues for nearly two years, creating instead a more formalized process with largely the same membership under the auspices of the organization's Aerodrome panel. "ICAO decided a systematical approach would be better," said Arun Rao, chief of ICAO's aerodromes and ground aids section. Though members continued to strategize in subgroups during the lull, the June gathering is the group's first formal meeting. The working group is slated to report its findings to the organization's Air Navigation Commission next year.


Fueling the work is a broad consensus in the international community that certain areas of the current standards are overly complex, and in some cases too conservative. As such, the working group's goal will be to craft a consensus that represents the best compromise between operational freedom and safety. Rao said any changes made will have to pass a litmus test for cost impacts to the industry as well.

One ICAO standard widely considered too conservative is the physical size of helipads and helidecks. Currently Annex 14 calls a load-bearing area of 1.5 "D" width for helipads and 1 "D" width for helidecks, where D is sum of the helicopter's largest overall dimension (usually the rotor blade diameter, or 1RD) plus a buffer area. According to John Leverton, a representative for the International Federation of Helicopter Assns. in the proceedings, 1D is roughly equal to 1.2 times a helicopter's main rotor blade diameter (1D = 1.2 RD).

For helipads in the U.S., Federal Aviation Administration Advisory Circular AC 150/5390-2B recommends a load bearing area width of 1D. While the FAA currently doesn't offer recommendations for helideck size, there's a wealth of indirect guidance in the standards of nations like Canada, Australia and Norway, and organizations like the American Petroleum Institute (API) and the International Maritime Organization (IMO).

In most if not all cases, however, member nation pads are smaller than what's implied in ICAO's Annex 14. Bob Bonanni, an engineer in the FAA's Airport Engineering Branch, said the FAA has "agreed in principle" to publish its own helideck guidelines as part of a future revision of its helipad Advisory Circular, a development he said will be a two to three-year effort once underway. "We don't see that happening any time soon," he adds. In the meantime, Bonini said operators like the U.S. Coast Guard, who follow the IMO's recommendation for a 1RD load bearing dimension for helidecks, have to report such differences directly to ICAO, justifying that they can achieve an equivalent level of safety with the smaller pads. In areas where the FAA provides guidance, the FAA takes on the job of negotiating with ICAO.

The difference in pad width becomes significant when considering the area involved. To increase a square helipad from 1D to 1.5D width, an operator has to beef up more the double the size of the original pad. It's an investment operators are reluctant to make. Leverton said the U.S. has approximately 5000 heliports and 2000-plus helidecks and has "no documented problems" linked to smaller surface areas. As such, Bonini said the helicopter industry in the U.S. "would certainly like to see ICAO come around to their way of thinking."

Perhaps more divisive and more ripe for change are ICAO's relatively complex and conservative standards for the airspace surrounding landing and takeoff corridors. A key issue is whether operators can penetrate the so-called Height/Velocity stay-out zones, aircraft-specific combinations of altitude and speed which would preclude a safe autorotation if power fails soon after takeoff or soon before landing. Airspace design for the approach and takeoff corridors for FAA heliports is fairly straightforward: A wedge of airspace 4,000 ft. long and 500 ft. wide at the end farthest from the heliport, with an 8:1 slope (7.1 deg.). The H/V curve can be impinged providing there's no safety of flight issues. ICAO on the other hand calls for avoiding the H/V problem zone, a principle that necessitates an airspace design with multiple slopes for takeoff and landing, starting shallow in order to build speed, and getting progressively steeper. The actual parameters are defined by a particular helicopter's performance characteristics and are meant to allow a helicopter to safely decelerate on landing and accelerate on takeoff. The result, however, is a more complicated airspace design that's different for day or night, landing or takeoff. ICAO's cautious approach, said Bonini, is an effort to limit risks to people and objects near the heliport if a helicopter goes down. "They plan to have that area cleared," he said. "We think that's overly conservative."

ICAO does not disagree with the need for change. "Five years ago, I had some of my own questions," said Rao. "Further questions came from the members and the Air Navigation Commission agreed there was a sound basis (to study potential changes)." Rao said there was "no loss of momentum" in transitioning from last year's study group to this year's working group, an assessment Leverton agrees with. The FAA's Bonini, however, feels that the transition will slow down the change process because the working group allows for more member nations to join the effort, Russia being the first new member. "It's more complicated," said Bonini. "It will set us back in getting other countries up to speed."

Whether or not the change extends the end game, most agree that harmonized regulations will be worth the wait. Although countries have the ability to waive ICAO standards if their own national practices differ, the path of minimum resistance is generally to side with ICAO. "States get audited against the ICAO (standards)," said Leverton. "There's an obligation to follow as nearly as possible what's in the Annexes."

Bonini points out that the FAA will maintain its prerogative to trump the end game if necessary. There is "nothing right now that said we're going to adopt whatever comes out of ICAO," he said. "It's real preliminary to say there's going to be an impact."

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