Mountain helo pilots share lifesaving lore

 - January 9, 2008, 8:43 AM

Helicopter mountain rescue operations are among the most demanding flying there is. Pilots are challenged by pushing the performance envelope of their machines in notoriously unpredictable weather, and when the mission is rescue, they face another layer of difficulty, driven by the desire not only to survive their mission, but to save lives too.

European mountain helicopter operators met recently in Chambéry, in the French Alps, at a seminar set up by Montanea, a French Alpine recreational, environmental and promotional organization, as part of its “international year of the mountains” celebration.

The gathering attracted operators from France, Germany, Italy and Switzerland–namely the French Sécurité Civile, Gendarmerie (national police force) and army; the German Bundesgrenzschutz (federal border police); the Italian region of Aosta’s Civil Protection; and the Swiss Rega Air Guard.

Notable among seminar moderators was Eric Fraissinet, founder and CEO of Secours Aérien Français (SAF), a privately owned mountain-rescue, air-charter and aerial work helicopter operator based in Frontennex, near Chambéry.

Attendees talked about their experiences, mainly in rescue operations, with subjects such as specific mountain-area dangers, flight in icing conditions and night-vision-goggle operations. The seminar stressed to attendees that although the missions they fly and their environments are similar, the way they fly is not always the same.

Emmanuel Sillon, commanding officer of the air division of the French Gendarmerie in Bron, which operates Alouettes IIIs, discussed the dangers a helicopter pilot can face when flying rescue operations in mountain areas.

For example, he said, air density is lower at altitude, causing engine and blade efficiency to decrease and thus available power to drop significantly. The flight crew can also be affected by the altitude, but an experienced pilot usually is acclimated to these elevations, Sillon stressed. “We try to operate with medical personnel who are used to working in mountain conditions.”

Specific mountain wind conditions also need to be taken into account. Downdrafts are often difficult to overcome, Sillon said. He also mentioned spiraling winds that rise from bowls, wind shear and Venturi effects, with wind picking up speed in some terrain configurations. Nebulosity and precipitation are markedly different from those found in nonmountainous areas. “Weather conditions change rapidly; a thunderstorm can happen suddenly and, of course, its precipitation can sharply reduce visibility. Icing and the loss of visual cues can cause accidents,” he reminded.

The terrain itself is hazardous because it can conceal the horizon reference. “It is often difficult to estimate relative heights around the place where you intend to land,” Sillon added. He stressed the value of having a good knowledge of the massif. “That is why we try to maintain links between old and new pilots within our division,” he said.

Light conditions often include snowblindness and “whiteouts,” when the delineation between snow and cloud is nonexistent. Last, but not least is the danger presented by the surface itself, which is not always favorable for landings. Snow can be soft, powdery and sometimes unstable.

Further, there are also some dangers that are linked to the type of mission. “Sometimes there is little safety margin,” Sillon acknowledged. Having to transport a variety of passenger types–rescue personnel, medics, etc.–can make things difficult, he said. Some of these passengers are not familiar with mountain conditions and often their priority is landing as close as possible to the injured person, whereas the pilot is looking for the safest place. In addition, the flight crew sometimes has to deal with requirements from local authorities and inquiries from the media. “You can also have pressure from the injured person you are carrying,” noted Gilbert Ramseier, a pilot with Rega, the Swiss air guard.

Flight into Known-icing
Icing conditions are a major danger when flying in mountain areas, and helicopters are usually not equipped to tackle such hazards. Col. Gunter Carloff, a pilot in the Federal German border police (Bundesgrenzschutz), said icing conditions can be found in Germany six months a year, which is why the Bundesgrenzschutz chose a helicopter certified for flight into known-icing.

“Today, flights in icing conditions are certified for only the Eurocopter AS 332-L1 Super Puma and Sikorsky Black Hawk, almost without restriction,” he said. The Bundesgrenzschutz operates three Super Pumas, among the aircraft in its fleet. The anti-/de-icing system in these helicopters consists of electrical heating of the main- and tail-rotor blades, inflatable boots around the leading edge of the stabilizer, and heating of engine inlets, pitot tubes and cockpit windows. An ice detector indicates the rate of accumulation.

No other helicopters are allowed to fly into known-icing conditions and they must immediately exit an area when icing is inadvertently encountered. “The Bell 214ST is certified in the UK for flight in moderate icing, and the Bell 212 for traces of icing above an outside air temperature of -5 degrees Celsius (-23 deg F). Even the huge CH-53 is allowed to fly in light icing for only a very short period and only to change altitude [to depart the area],” Carloff clarified.

Moreover, as helicopters do not carry an oxygen supply for passengers, they cannot use altitude to escape severe icing. Carloff described an encounter in moderate icing with a helicopter that is not certified for icing conditions: “Neither climbing nor maintaining the desired altitude is possible. Massive vibrations prevent you from reading the instruments, and both pilots try to control the erratic movements of the sticks for a controlled descent.”

After “hundreds of flights” in icing conditions, the Bundesgrenzschutz has ordered a Eurocopter EC 155 fitted with de-icing equipment. Certification is pegged for next year, said Daniel Bouheret, head of the all-weather helicopter program at Eurocopter. The de-icing system found on the EC 155 will be similar to the Super Puma’s.

Conventional anti-icing or de-icing relies on heating the surface to prevent formation of ice, or inflating rubber tubes to shatter an ice layer. “This is expensive and heavy, and consumes a lot of energy,” Bouheret pointed out. On the Super Puma, the de-icing system weighs as much as two passengers.

Other systems are being explored for de-icing medium and light rotorcraft. For example, piezoelectric systems employing electric impulses to induce small vibrations to break the ice would allow de-icing of curved surfaces not possible with today’s boot systems. “But they are power-hungry and providing enough electricity would carry a hefty weight penalty,” Bouheret told AIN. A more promising way is the optimization of conventional solutions. “We can make sensors more accurate to avoid using more heat than needed,” Bouheret said.

Also under study is a process of heating a blade section rather than a whole blade. “Should just one section fail, you can closely keep the rotor’s balance,” Bouheret said.

The attendees also discussed IFR helicopter operations. Although not widespread in Europe, all operators present agreed that rescue operations should benefit from, or at least be influenced by, IFR techniques. The Bundesgrenzschutz conducts IFR operations and Switzerland’s Rega has been authorized to set up special IFR air corridors for interhospital helicopter transfer flights using EC 145s. “In the U.S., today there are 220 DGPS-equipped, IFR-capable heliports; three years ago there were only 108,” noted Jean-Pierre Brassler, senior manager for market research.

Night-Vision Goggles
Another device that draws much interest in the field of mountain rescue operations is night-vision goggles. Rega pilot Gilbert Ramseier said his crews use goggles that display a monochromatic green image with a 42-deg field of vision. “We do not change our operating minimums with NVG,” he explained.

The benefits of using NVG include improved weather awareness and earlier obstacle avoidance, said Ramseier, but drawbacks are the limited field of vision and a significant loss in depth of field. “We have performed 16,000 NVG missions since 1988–26 percent of our missions,” he noted. Night operations can be classified into several categories, the most difficult being 8,000-ft visibility and 1,000-ft ceiling. Rega does not use NVG when close to or on the ground, and pilots use direct visual cues for takeoffs and landings.

But French Army light aviation warrant officer Franck Rossit presented a different point of view: “We believe it is better not to change visual cues during the approach, and we use our goggles until touchdown,” he said. French Army NVG procedures compensate for the limited field of vision by using all eyes on board, including the mechanics in the back who are not wearing goggles.

Bundesgrenzschutz’s Carloff insisted that both pilots–if there are two–must use the goggles: “Both  pilots must see the same environment,” he said.

All the aforementioned discussions were about binocular goggles. “We tried monocular goggles but they caused air sickness or headaches,” Carloff said. Monocular goggles cause the eyes not to look in strictly parallel directions, he added.