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Analysis: EC635s in the Alpine skies

25th January 2017 - 12:00 GMT | by Davide Daverio in Carnago


The Swiss Air Force used to operate 32 Alouette IIIs and when the time came to change the fleet, the EC635, also known as the H135M, was selected. 

Key considerations of the model selection included a reduced maintenance cycle and more efficient capabilities.

The first four helicopters were built in Germany and delivered to the Swiss Air Force in March 2008, while the remaining 16 were locally assembled by Ruag and delivered between 2008 and 2010. After over six years of operation, the choice proved to be consistent with the requirements of the Swiss Armed Forces. 

The rear access doors placed under the junction between the fuselage and the tail boom make it possible to carry two stretchers. (All photos: author)

From a training perspective, the commonality of the cockpit between the Super Puma and the Cougar has considerably reduced the flight hours, while the presence of updated avionics and the supply of a flight simulator has helped to contain operating costs.

The helicopter is constructed with aluminium and carbon fibre. There is the possibility to install external armament thanks to a reinforced cell.

The barycentric hook under the fuselage has the ability to carry heavy loads of up to 1,000kg, for both military operations and civilian use, including fire-fighting missions through the usage of a Bambi Bucket.

The use of the external winch, positioned above the hatch on the side of the fuselage, makes it suitable for SAR missions on the mountains - often the Swiss Air Force collaborates in the search for missing persons over the Alps.

The rear access doors, placed under the junction between the fuselage and the tail boom, make it possible to carry two stretchers, conferring the helicopter for the role of rapid transportation of injured and casevac, with a doctor and a specialist on board.

In fact, in addition to the pilot and co-pilot, the fuselage can accommodate up to six passengers, although four are normally carried – the VIP version can accommodate only four persons.

A huge advantage of the aircraft for the armed forces is the ability to fly in accordance with the IFR standard - this  was not possible with the Alouette, which could only be flown as VFR.

The cockpit is built around two multi-functional displays which populate different digital pages displaying the status of the helicopter and the installed systems, a digital map, the flight plan and the radio frequencies. The cockpit is compatible with night vision goggles, in order to operate at night and extend the envelope of use. 

The cockpit is equipped with digital maps and GPS, which help to ensure precise positioning in all weather conditions.

Another innovation compared to its predecessor is the presence of GPS integration with the avionics suite. This has made it possible to navigate point-to-point, avoiding the need to follow routes, with a consequential reduction in operating costs and the timing reach waypoints.

For example, the approach manoeuvre at the base can be performed following the GPS direction rather than the standard approach as reported on airport maps.

From the pilot’s point of view, two major differences have led to a change of use procedures. The first is the absence of the classic tail rotor, replaced by the Fenestron design, which makes the cruise simpler with fewer rudder corrections, but induces the pilot to continuously intervene during hovering. 

One of the main aspects for the selection of the helicopter was related to its lower noise pollution levels. The second is represented by the replacement of the tricycle landing gear that equipped the Alouette III with the skids, less suitable for the use over the mountains.

According to Capt Stauber, an experienced air force pilot with over 1,100 flying hours on the Alouette III and EC635, flying at a high altitude with the first model was very easy, while the latter platform is very sensitive to lateral wind and this must not be underestimated. Therefore, the type must be flown upwind to avoid continuous trimming.

In addition, the presence of tricycle gear was appreciated for extreme mountain operations, as it was easy to find a foothold or steep land to put one or more wheels on, allowing for descent or recovery of the staff.

The EC635 is very sensitive to lateral winds and must be flown upwind.

In its favour, the EC635 has the higher cruise speed and the ability to fly in adverse weather conditions thanks to the presence of a modern cockpit (even in comparison with the Super Puma and Cougar) with digital maps and GPS, which ensure a precise positioning in all weather conditions, and has an instrumentation that makes the IFR flight possible.

The autopilot is sophisticated and is much more advanced than even the Cougar. The two engines make it safer flying in the Alps territory, with the capability of being able to return to base with just one operational. This latter feature also translates into an advantage in terms of training, as it anticipates the cadets’ management of twin-engine helicopters.

Still in terms of training, flight controls are common to those of other helicopters already in service with the Swiss Air Force, so the transition is less difficult and helps the trainees’ familiarisation.

The communications suite includes a satellite phone, two VHF band radios, a UHF band one, a tactical radio (TRC, Tactical Radio Communication) and PoliComm radio. The radio allows contact with the police during joint operations or when the helicopter is assigned to national borders surveillance.

According to an agreement made some years ago, about 520 hours per year are flown for border control tasks, in collaboration with the Swiss Border Guard.

After six years of service with the Swiss Armed Forces, the 18 EC635P2+s have accumulated approximately 42,000 flight hours, carried out almost entirely on the national territory. In fact, the EC635 has never been sent to take part in exercises or international missions abroad. 

The only operations carried out outside of the national boundaries are for training missions conducted at German airports, where crews have been able to train with the staff of the Bundeswehr. It was there that they were able to enhance their skills in IFR flight.

Davide Daverio


Davide Daverio

Davide is a Shephard Media correspodent based in Italy.

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