New ICAO procedures should widen IFR ops

 - April 30, 2007, 11:38 AM

The obstacle clearance panel (OCP), a group of experts in the International Civil Aviation Organization (ICAO), is designing more suitable IFR procedures for helicopters, taking advantage of new navigation equipment. Under the proposed rules, scheduled to take effect in the fall of next year, precision guidance on low-level routes to so-called points in space will become common.

“Until recently, there was almost no operating a helicopter under instrument flight rules,” Yves Coutier, a French representative on the OCP, told AIN. He said there are few dedicated heliports compatible with IFR obstacle clearances, which are basically standards for fixed-wing aircraft. In addition, there is no suitable means of guidance for helicopters, as these standards, too, were designed for airplanes. Finally, he said, “helicopter pilots…have skills in flying visually in marginal weather, which airplanes can’t do.” As a result, helicopters have long been subject to the same rules as light piston aircraft because the two types have similar approach speeds.

But things are about to change. “Helicopter technology has evolved to [include] more instruments, more automation,” Coutier said. As a result, new means of guidance can be adapted to helicopter needs. Global navigation satellite systems, unlike conventional instrument landing systems, do not need local ground equipment any longer “so [the operator does not] have to meet a given volume of activity to justify the expense of installing the equipment,” Coutier said.

Point-in-space Approaches

“Point in space” operations have become routine in Australia and the U.S. The idea is to design an IFR route that ends at a relevant point near a heliport. From there, the crew then flies VFR to the destination. In instances in which a direct IFR approach is not feasible because of obstacles, points in space can improve safety significantly.
“The majority of helicopter accidents happen en route, when pilots fly VFR, near the ground, in poor weather,” Coutier noted.

So far, points in space in use have relied on GPS guidance alone. ICAO now wants to harvest the fruits of augmented systems, such as WAAS in the U.S. or EGNOS in Europe, which yield better precision because they offer lateral and vertical precision navigation.

Operators’ needs vary, depending on which side of the Atlantic they live. In Europe, where noise is an overarching concern, operators and local authorities want helicopters to perform steeper approaches to reduce the noise footprint.

Many European operators are ready to pay for the required equipment to make approaches at more than six degrees of slope. At such an angle, it is almost impossible to decelerate without a four-axis autopilot. Eurocopter has developed just such an autopilot and has been lobbying for new standards to allow vertical precision guidance. Coutier said the company does not want its “investment to be fruitless because of a lack of standards when there is a clear need, available technology and money to pay for the product.”

U.S. operators, on the other hand, have historically had fewer problems with local residents about noise, Coutier said. Moreover, the huge U.S. fleet would be expensive to retrofit with equipment that enables a steep approach. As a result, operators are interested primarily in lateral guidance and count on obstacle-free approaches, with modest angles.

Acknowledging that operators on different sides of the Atlantic have different needs, the OCP is developing a dual standard, writing a “lateral guidance only” rule as well as one that combines lateral and vertical guidance. “Each country or operator will pick its preferred rule,” Coutier told AIN.

So far, the U.S. industry has been active in providing the OCP feedback on its experience with lateral guidance. However, according to Coutier, Eurocopter still has to accelerate its vertical guidance experiments.

There are two types of points in space–close and remote–and choosing between the two depends on the operational need and the size of the nearest obstacles.

In the case of a “close” point in space, the principle is to reduce the segment flown visually to the minimum possible. It is easier to implement with an augmented satellite navigation system. In other words, this is where better precision, even though only lateral, holds benefits.

In the case of the “remote” point in space, the idea centers on the importance of breaking through the clouds, Coutier explained. It is compatible with conventional satellite navigation systems, such as GPS. The last segment of the flight will be flown under visual flight rules. In Europe, this sort of point in space will thus not be operational at night, Coutier said.

So how near or far should a point in space be from the heliport to be classified as “close?”  About three kilometers (10,000 feet), Coutier said.

The revised standards scheduled to be released next fall will address approaches at angles of up to six degrees, the use of augmented satellite navigation systems in lateral only and lateral/vertical precision guidance to a point in space and use of these systems in the visual phase beyond the point in space.

Later, when the group develops new standards for steep approaches–those above six degrees of slope angle–it will take into account feedback collected from approaches at six degrees or below.    

Integration at Major Airports

One application of the Obstacle Clearance Panel’s point-in-space studies is how to integrate helicopters into major airport traffic without losing capacity. “Because of the difference in speed, a helicopter today needs twice the airspace an airliner is allotted,” said the panel’s Yves Coutier.

Last month, the panel tested a plan that hinges on a point in space one kilometer (3,300 feet) from the airport. It involved vertical guidance to the point in space. If the plan works, rotorcraft that seat 50 passengers could be used as feeders at major airports without interfering with conventional traffic.

What is the OCP?

The Obstacle Clearance Panel (OCP) consists of 19 experts representing 19 countries. Australia, Canada, Denmark, France, Germany, Japan, Spain, the U.S., China, Brazil, South Africa, Russia and the UK each have their own representative. In addition, one expert jointly represents Belgium, the Netherlands, Luxembourg, Switzerland, Ireland and Austria.

The other five panelists are named by the International Coordinating Council of Aerospace Industries Associations, the International Air Transport Association, the International Federation of Air Line Pilots Associations, the International Federation of Helicopter Associations and Eurocontrol.

The OCP reports to ICAO’s Air Navigation Commission (ANC), which develops standards and recommended practices. Member states are consulted but the ANC has the final word. However, a state can publish a difference in rule implementation.

Expert panels, which make a new set of recommendations every two or three years, are permanent. To the contrary, specific working groups can be created and terminated ad hoc. The ANC uses both panels and working groups to propose new rules to member states.