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Simulation of Upset Recovery in Aviation

Tags: Air

State of the Art - Background

Safety reviews list Loss of Control In-flight, LOC-I, as the leading cause of fatal accidents in transport aircraft. Between 1997-2006, LOC-I accounted for 87 accidents (2,573 fatalities) worldwide, 12 of them in EASA Member States. A large number of these accidents have been attributed to unsuccessful recovery from an 'upset', i.e. an aircraft inadvertently exceeding the flight parameters normally experienced in line operations (such as a roll angle of more than 45 degrees). Typically, a lack of awareness and experience by the crew allows the situation to become critical, resulting in loss of the aircraft. While these situations do not occur on a regular basis, their results are invariably catastrophic.

Aviation authorities recognise the clear need to educate pilots in upset recovery techniques. Performing such training in real aircraft would be expensive and unsafe. A cost-effective and safe alternative is to use a ground-based flight simulator, especially since commercial pilots already receive their recurrent training in a simulator. However, current flight simulators are considered inadequate for upset recovery training, since the aerodynamic models and equations of motion apply to the normal flight envelope, which is not representative of the extreme flight conditions associated with an upset.


The global objective of SUPRA is to develop and validate a new flight simulation concept for teaching pilots to recover from a flight upset.

The technical objectives of SUPRA are:

- to perform actual flight tests to measure aircraft behaviour in upset conditions;

- to extend aerodynamic models beyond the standard flight envelope;

- to develop innovative motion-driving algorithms to provide motion feedback to the pilot representing in-flight upsets;

- to develop a Bayesian motion-perception model for objective optimisation of simulator motion.

The results of the project will become the basis for optimising standard training simulators for upset recovery training, as well as the development of specific flight simulators, capable of simulating exceptional flight conditions. The requirements will be laid down in a set of guidelines. SUPRA will contribute to ensuring that aviation safety remains at the current high standards or even improves, regardless of the growth in air transport.

The consortium will combine unique expertise and simulator facilities, such as the new motion platform Desdemona (see figure). With its gimballed cockpit and centrifuge capabilities, extreme attitudes and sustained G-loads can be simulated.

Description of Work

SUPRA is divided into seven technical work packages (WP).

WP1 obtains data from accident analyses, flight data recordings and flight tests.

WP2 extends the mathematical models of aircraft dynamics beyond the normal operational flight envelope to account for unsteady non-linear aerodynamics in upset conditions.

WP3 consists of hardware modifications to the research simulators. A debriefing tool will be developed which allows for the evaluation of pilot performance in upset recovery training.

WP4 encompasses psychophysical experiments to build a knowledge base on visual-vestibular interactions. The experimental data will be input for the development of a new Bayesian perception model, showing how well certain simulator cues lead to the correct self-motion perception.

WP5 develops the special motion driving algorithms which accommodate the simulator motion envelope to the high accelerations and attitudes characteristic of upset situations. For hexapod simulators, existing motion driving algorithms will be optimised, and for the unconventional motion platforms, completely new motion driving algorithms will be developed.

WP6 integrates the extended aircraft models and motion-driving algorithms into the research simulators for the final validation of upset recovery simulation.

WP7 integrates the results to formulate guidelines for simulator-based upset recovery training.

Expected Results

The deliverables of the project are:

- a documented set of relevant flight upsets and required recovery techniques;

- an extended mathematical aerodynamic model;

- innovative motion driving technologies;

- guidelines to retrofit existing training simulators for simulation of (certain) flight upsets;

- guidelines to perform (certain) upset recoveries in dedicated motion simulators;

- Bayesian motion perception model.

The results of SUPRA will become the basis for optimising standard training simulators for upset recovery training, as well as the development of specific flight simulators, capable of simulating exceptional flight conditions. This way, SUPRA will contribute to further improving aviation safety, regardless of air transport growth.