Pilots around the world can practise recovering control of their aircraft after entering a stall, using a simulation model developed by the EU-funded SUPRA project. By simulating such situations, the project fills a gap in current pilot training, and aims to improve air travel safety.


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Aerodyamic stall modeling

The SUPRA model is currently being used at the Desdemona flight simulator, located in Soesterberg, the Netherlands. The simulator is being used to research pilot performance in extreme flight situations and to train commercial pilots to recognise and recover from stalls.

A training course has been developed out of the research and is currently being offered to airlines around the world. Desdemona – with its unique motion platform – is capable of reproducing the g-forces associated with stall recovery, providing pilots with a realistic experience of aeroplane behaviour in these extreme situations.

“As this training is not yet being mandated by aviation authorities, operators decide on a voluntary basis to send their pilots to Desdemona, which some are doing,” says project coordinator Eric Groen of TNO.

Regulators, including the European Aviation Safety Agency, are currently developing rules that will mandate upset prevention and recovery training for commercial pilots, Groen says. This may involve extending simulator capabilities to reproduce aeroplane behaviour in stalled conditions. The SUPRA model offers this training component.

The SUPRA model can be used by manufacturers to retrofit existing simulators, or to develop new ones that represent extended flight training. Project partner AMST is currently developing a standard simulator with the SUPRA flight model into a dedicated training device for stalls.

The SUPRA project ended in August 2012. Since then, TNO and Boeing have developed a tool to help in the analysis of flight data recorder information to determine the possible contribution of a pilot’s spatial disorientation to an accident. “The tool is based on collected data on pilot perceptions that was used within SUPRA to evaluate the fidelity of simulator motion,” Groen says. “The ‘Spatial Disorientation’ tool is another application of the same model; hence it is a nice spin-off project for TNO.”

Simulation of Upset Recovery in Aviation

For pilots, one of the most difficult skills to learn is ‘upset recovery’ – righting a plane that has stalled or been thrown into an unstable situation due to weather or a technical problem.

Upset recovery

When a pilot is not able to fly out of an ‘upset’ and the plane proceeds out of control, accidents can result. And it is precisely because these extreme conditions seldom occur in real life that it is hard for a pilot to be prepared for them: up to now, no flight simulator reflects adequately how an actual aircraft behaves during upset situations. Alternative training methods – such as using large commercial aircraft for training or smaller ones – are either too dangerous or expensive, or may not be comparable to how large aircraft behave and respond.

Flight experts around the world have called for improved training on such situations. To remedy the situation and give pilots the critical training they need, the European Union (EU) funded project SUPRA – or “Simulation of Upset Recovery in Aviation” – developed what has been called “the ultimate flight simulator”.

SUPRA has enhanced flight simulators beyond their current capabilities. The project comprised a unique team that included aerospace research companies, a university, a flight test centre, a developer of flight simulators, and a cognitive research institute. Three Russian partners plus a “satellite” team of Russian physicists in the United Kingdom joined in with specific expertise that is hard to find inside the EU.

“Collectively, the Russian scientists represented an impressive amount of knowledge and experience in all key innovative areas of the project,” says project coordinator Eric Groen of the Dutch research organisation TNO.

With expertise in wind tunnel testing, simulator motion, flight testing, aircraft handling and other specialised areas, the Russian partners gave SUPRA a valuable head start. A Russian test pilot flew numerous flights in the simulator, identifying inadequacies that were adjusted and tested until the simulator felt exactly like a real aircraft.

“Our Russian partners were highly motivated to participate and achieve results,” comments Groen. “Altogether, SUPRA has greatly benefited from the Russian expertise and their efforts, which undeniably contributed to the project’s success.”

Groen further explained that the SUPRA team developed a new mathematical model that satisfactorily reproduces the behaviour of large transport aircraft in extreme situations. Relying on this model, the simulator can move and spin wildly in all three dimensions, replicating an aircraft that is hurtling out of control. This will help train pilots to develop strategies to keep or regain control of an aircraft.

Experienced test pilots from companies including Airbus and Boeing, who know from experience how large transport airplanes behave in upset situations, have worked to evaluate the fidelity of the SUPRA simulators. Their judgments have been very positive.

The SUPRA team, meanwhile, assessed the pilots' motion perception in conditions similar to actual aircraft upset situations. The experiments' results indicate that using the simulator can prepare a pilot for dealing with a crisis, simply by knowing what to expect. “What we have discovered,” says Groen, “is that if you have a pilot who has little or no experience with actual G-forces during upset conditions in a real aircraft, the pilot will be overwhelmed when he first feels them.”

This bodes well for vast practical applications of SUPRA’s work. “Currently regulators are making rules that will mandate upset recovery training for commercial pilots,” explains Groen. “This will facilitate the industry to adopt the results of SUPRA to improve their pilot training programmes. With our technology we can upgrade those existing simulators to reproduce the upset recovery behaviour in a correct way.” Several European airlines have already shown interest in the technology and the team is now showing its results to various aviation organisations responsible for pilot training.


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