The European research project "Simulation of UPset Recovery in Aviation" (SUPRA) successfully developed new flight simulator technologies. SUPRA pushed the simulator's aerodynamic and motion envelope, enabling airline pilots to recognize and manage upset events, including aerodynamic stalls, typical of transport aircraft.

The three main products of SUPRA are:

  1. An enhanced aerodynamic model beyond the normal flight envelope, including stall characteristics;
  2. New motion cueing solutions which provide realistic feedback about aerodynamic buffet and G-loads;
  3. Pilot motion perception model.

As upset recovery training in real transport aircraft is too risky and expensive, the solutions developed by SUPRA offer a unique ground-based platform for demonstrating aircraft behavior in upset conditions, building G-awareness, and practicing recovery techniques.

Simulation of UPset Recovery in Aviation

Unsuccessful recovery from upsets, which involve unusual attitudes and aerodynamic stalls, may lead to Loss of Control In-flight (LOC-I), today’s leading cause of fatal accidents in commercial aviation. There is a clear need to educate flight crews in upset recovery techniques. Exercising upsets in transport aircraft is unsafe and prohibitively expensive, and, if performed in smaller aircraft, may not be representative of large transports. Therefore, simulation of upset conditions offers great benefits for pilot instruction.

However, simulator training of upset recovery is limited by two major technology gaps:

  1. Simulator aerodynamic models only apply to the normal operational flight envelope, which makes them unrepresentative for the unstable behavior at high angles-of-attack.
  2. The standard hexapod motion platform of current flight simulators is unable to reproduce the high accelerations, angular rates, and sustained G-forces associated with upsets.

Simulation of upset recovery in aviation


The SUPRA project was targeted at the following European Commission objectives:

  1. Reduce aircraft accident rate by 80%
  2. Improve elimination of, and recovery from human error


The SUPRA project’s success was the result of a multidisciplinary effort by ten established research organizations throughout Europe:

(NL) TNO (project coordinator), Desdemona, NLR
(RU) TsAGI, GFRI, CSTS Dinamika
(UK) DeMontfort University
(DE) Max Planck Institute for Biological Cybernetics
(ES) Boeing Research & Technology Europe

External Expert Group

An independent group of 15 subject matter experts was involved to evaluate the research plans and deliverables of SUPRA. The group included test and airline pilots from various organizations, flight control experts and modeling experts.

Funding and Duration

The SUPRA project was funded by the 7th Framework Programme of the European Commission, Aeronautics & Transport (Aircraft Safety).

Total project budget: € 4.9M (EC: € 3.7M)
Duration: Oct 2009 – Aug 2012

SUPRA consortium

SUPRA consortium locations

SUPRA experts


The project developed breakthrough technologies that reproduce the unstable flight dynamics of transport aircraft at high angles of attack, including fully developing stall.

Using a combination of phenomenological modeling, wind tunnel test data and Computational Fluid Dynamics (CFD), SUPRA developed a generic model of transport aircraft capturing the key aerodynamic phenomena in (post-)stall conditions. This includes longitudinal and lateral instabilities, ineffectiveness and reversal of controls, randomness and variable intensity.

Simulator facilities

The SUPRA project featured three state-of-the-art research simulators.

At TNO, the DESDEMONA centrifuge-based simulator features an unequalled motion envelope with a fully gimbaled cockpit, a 2-m vertical and 8-m horizontal stroke length, and a centrifuge capability enabling G-loads up to 3g, representative of the load limits of large transport aircraft. In the DESDEMONA simulator both the subject matter expert validation and experiment with line pilots were performed.

The NLR Generic Research Aircraft Cockpit Environment (GRACE) is a reconfigurable research simulator with a 6 DOF electric motion base, collimated visuals and configurable flight model. With this simulator, the effects of limited motion space in conventional simulators were investigated, as well as new motion cueing solutions.

The TsAGI PSPK-102 simulator is a reconfigurable research simulator with a 6 DOF motion base, which was used to establish motion perception criteria to improve motion driving algorithms

Motion Cueing

The the SUPRA project developed special motion cueing algorithms for different phases of flight. For example, normal flight was simulated with regular ‘onset cueing’, similar to conventional hexapod motion. Centrifuge-based cueing was used for recovery from stalls, or more general, nose-low attitudes, providing the pilot with the actual feel of G-loads. Transitions between different cueing phases were managed by a scheduling module.

Motion Perception

Over the years, TNO has developed a mathematical model to predict the pilot’s motion perception in the real aircraft as well as in the simulator. During SUPRA, the model was further extended to cover the motion fidelity of conventional hexapod simulator motion and centrifuge-based G-cueing. This work included a series of new simulator experiments, which helped to optimize the simulation of critical motion cues, while minimizing the false cues.

SUPRA Computational Fluid Dynamics (CFD)

Experiments with line pilots

A group of seventeen civil pilots, without previous G-maneuvering experience, participated in two simulator studies. First, it was shown that pilots tend to overestimate G-loads. With brief training their performance instantly improved. A retest after six months shows that the improvement did not endure. The second experiment shows the additional value of centrifuge-based G-cueing in relation to flight performance during recovery from nose-low unusual attitude. From the study it can be concluded that G-cueing simulation improves upset recovery performance of civil pilots, compared to fixed-base simulation, which may result in more realistic and adequate recovery training.

Validation with test pilots

In total, twelve highly qualified test pilots validated the handling qualities of the SUPRA solutions in the normal flight envelope, as well as the stall and post-stall conditions. These expert pilots concluded that the SUPRA model adequately covers the aerodynamic phenomena in upset conditions, and offers valuable advances over the current state-of-the-art. The SUPRA environment was considered a major improvement over current simulators, and centrifuge-based G-cueing was judged an adequate instrument to build G-awareness.

DESDEMONA centrifuge-based simulator

EC Documents

Final report summary SUPRA

Final report SUPRA


Euronews movieclip SUPRA

Scientific Output

SAE Nooij, M Wentink, H Smaili, L Zaichik, EL Groen (2017) “Motion simulation of transport aircraft in extended envelopes: Test pilot assessment”, Journal of Guidance, Control, and Dynamics 40 (4), 776-788.

WD Ledegang, EL Groen (2015) “Stall Recovery in a Centrifuge-Based Flight Simulator With an Extended Aerodynamic Model,” The International Journal of Aviation Psychology 25 (2), 122-140.

KN De Winkel, F Soyka, M Barnett-Cowan, HH Bülthoff, EL Groen (2014) Integration of visual and inertial cues in the perception of angular self-motion. Experimental brain research 231 (2), 209-218

WD Ledegang, EL Groen, M Wentink (2012) “Pilot Performance in Centrifuge-Based Simulation of Unusual Attitude Recovery”, Journal of Aircraft 49 (4), 1161-1167.

EL Groen, WD Ledegang, J Field, H Smaili, R Roza, L Fucke, SAE Nooij, M Goman, M Mayrhofer, L Zaichik, M Grigoryev, V Biryukov, (2012) “SUPRA–Enhanced Upset Recovery Simulation”, AIAA-2012-4630, AIAA Modeling and Simulation Technologies Conference, 13-16 August 2012, Minneapolis, Minnesota.

N Abramov, M Goman, A Khrabrov, E Kolesnikov, L Fucke, B Soemarwoto, H Smaili. "Pushing Ahead - SUPRA Airplane Model for Upset Recovery", AIAA CP 2012-4631, AIAA Modeling and Simulation Technologies Conference, Guidance, Navigation, and Control and Co-located Conferences, Minneapolis, Minnesota, August 13-16, 2012,

J Field, M Roza, H Smaili (2012) “Developing Upset Cueing for Conventional Flight Simulators”, AIAA CP 2012-4948, AIAA Modeling and Simulation Technologies Conference, Minneapolis, Minnesota, August 13-16, 2012, DOI: 10.2514/6.2012-4948.

N Abramov, M Goman, A Khrabrov, B Soemoworto (2010) “Aerodynamic Model Development for Simulation of Upset Recovery of Transport Airplane”, RAeS Conference on Aerodynamics Conference Applied Aerodynamics: Capabilities and Future Requirements. London, July 27-28, 2010.

L Fucke, V Biryukov, M Grigorev, V Rogozin, EL, Groen, M Wentink, J Field, B Soemarwoto, N Abramov, M Goman, A Khrabrov (2010) “Developing Scenarios for Research into Upset Recovery Simulation”, AIAA CP 2010-7794, AIAA Modeling and Simulation Technologies Conference, Guidance, Navigation, and Control, Toronto, Ontario, Canada, August 2-5, 2012,

Prof. Dr. Eric Groen, scientific coordinator SUPRA
Kampweg 5
P.O. Box 23
3769 ZG Soesterberg
The Netherlands
T: +31 88 866 59 26


Prof. Dr. Eric Groen (scientific coordinator SUPRA)