Helo satnav approaches make slow progress in France

Aviation International News » February 2010
January 28, 2010, 6:00 AM

The French helicopter industry is endeavoring to catch up with the U.S. in satellite-aided precision approaches, as it strives to enable landings and takeoffs at hospitals in IMC. The ultimate aim is to build a solid network of inter-hospital low-altitude IFR routes, according to participants at a forum held by the Toulouse-based air and space academy late last year. The project involves the DGAC (France’s civil aviation authority), Eurocopter and the association of those medical personnel who use helicopters (AFHSH).

The French government’s policy of favoring the consolidation of medical skills means fewer hospitals will have, for example, surgery capabilities. The idea is to maintain the specialists’ proficiency by exercising their skills–just as in aviation–and it depends on reliable, fast transportation between hospitals.

A test route has been established between Nogent-le-Rotrou and Dreux hospitals, in northwest France, and operations should begin immediately after publication of the procedures by next winter, according to DGAC program manager Cédric Tedesco.
Europe’s satellite-based GPS augmentation system, Egnos, is slated to be operational by then, thus enabling precision approaches.

Next winter is almost one year later than previous expectations. “As we progress, we find issues in training, obstacle monitoring and so on,” AFHSH president Nicolas Letellier told AIN.

Tests are progressing somewhat more slowly than expected, impeded by some small issues, said Tedesco. For example, approach speed poses one challenge. The descent rate must not exceed 800 feet per minute on the final segment if the approach is to be kept stable enough for the patient’s comfort. For a six-degree glideslope, this limits the speed to 75 knots.

In addition, three-axis autopilots fitted on most current EMS light twins can perform the job properly down to 70 knots, but below that speed (which would be required for slopes steeper than six degrees), they can no longer control vertical speed through pitch control.

This increases pilot workload, requiring him to control the descent rate manually with the collective pitch lever, while the autopilot maintains airspeed. Such hybrid piloting technique has been tested successfully in flight with the EC135 and EC145, said Eurocopter research manager for operations and flight control Philippe Rollet, but the increase in pilot workload is a concern.

DGAC pilot Alexandre Antunes provided some feedback on the approaches he flew in an EC145.

Antunes is not type-rated on the EC145 (he was flying it with another pilot) and knew little about satellite approaches. Although starting a descent is “not difficult,” he said, vertical speed can be an issue if there is a tailwind. In fact, he reported that vertical speed sometimes exceeded 1,000 feet per minute to accommodate a tailwind.

Another challenge was the leveling-off phase at night, which is all the more crucial since the point in space is also the missed approach point. “You cannot go beyond it without visual cues,” said DGAC instructor and procedure designer Hervé Pradines.

Antunes noted that, in IMC, it was not always obvious to the crew that they had emerged from the cloud base. Also, recognizing the point in space could call for some involved visual searching, and Antunes suggested that a supermarket is easier to see at night than a roundabout. He questioned the wisdom of having a single pilot: “The workload can be heavy in the event of engine failure,” he said.

The accuracy of local weather reporting and forecasting also raises questions about the feasibility of these inter-hospital routes. “Light twins have no de-icing systems; their pilots must avoid icing conditions by flying at low altitude and having a better knowledge of the weather locally,” Rollet said.

Another issue mentioned at the forum was the lack of refueling facilities, which forces pilots to tanker sufficient fuel for a diversion.

Proponents of the routes acknowledge that the routes will incur some additional cost but they hope that equipment and training costs will be recouped as a result of increased aircraft utilization. Letellier warned that local authorities might have a different perception. For example, in Marseilles, one hospital is now using a proper helipad that can handle only one helicopter rather than the two that could operate on grass.

“In the recent past, we have had to replace single-turbine aircraft with twins. Now we are looking at having to pay for a second crewmember. One day, politicians could tell us, ‘These helicopters are starting to be a bit expensive for what you do with them,’” Letellier noted.

Creating the hoped-for network of low-altitude IFR routes may not be easy. Tedesco said Switzerland has been struggling for years with creating the associated network of terminal control areas. Moreover, the Ministry of Health has yet to confirm that it sees low-altitude IFR routes as the strategy to pursue.

Eurocopter’s Light Twins To Be STC’d for Waas

Eurocopter expects to receive FAA supplemental type certificates (STCs) for satellite-based augmentation systems, including Waas capability, for two of its light twins this year. The STC–for the EC135 and EC145–will be based on two Garmin GNS430 receivers, and retrofits could be available by the middle of this year. EASA approval is expected to follow.

Flying to Lausanne’s Hospital

Eurocopter recently conducted satellite-guided steep precision approaches to the hospital at Lausanne, Switzerland, under a European research project called Giant. European augmentation system Egnos, still in the experimental stage, guided an EC155 to a rooftop helipad. The 26 flights tested various kinds of approach, with pilots preferring the steepest ones (nine degrees). These approaches, they said, provided better obstacle clearance and noise abatement.

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