(1) Field of the Invention
The present invention lies in the field of man-machine interfaces for aircraft. It relates to a method and to a device for adapting the man-machine interface of an aircraft depending on the level of the pilot's functional state. The method and the device are intended more particularly for rotary wing aircraft.
(2) Description of Related Art
In an aircraft, continuous and both-way exchanges take place between the pilot and the aircraft. The pilot communicates with the aircraft via various flight controls and also via various data input means, such as a keypad, a pointer, e.g. a touch tablet enabling certain parameters to be specified, or various switches. Similarly, the aircraft communicates a large amount of information to the pilot, in particular relating to flight conditions, to parameters of the aircraft, and to the outside environment. By way of example, the information may be communicated visually by means of various screens or directly on the pilot's helmet visor, audibly by issuing an alarm or by using a voice synthesis device, or indeed by the sense of touch, by making use of vibration in one or more of the controls of the aircraft. Furthermore, the aircraft may also take charge of the piloting of the aircraft during certain stages of flight by means of an autopilot.
These elements enabling communication to take place between the pilot and the aircraft are referred together as constituting the man-machine interface, commonly specified using the initials MMI. When the aircraft has a copilot, the MMI also enables communication to take place between the copilot and the aircraft. Nevertheless, the description below is limited to communication between the pilot and the aircraft, it being understood that the pilot could be replaced by the copilot at any time.
Nowadays, such an MMI enables the pilot to be informed by providing the pilot with all of the available information depending on the various stages of flight of the aircraft and/or on flying conditions. However, since the piloting of an aircraft is becoming ever more complex, it is advantageous to be able to provide the required information to the pilot at a time that is appropriate. Nevertheless, although human factors are taken into account when designing an MMI, they are not taken into account during a flight. The list of all the information to be presented and the way in which it is to be presented in real time are independent of any human factors associated with the pilot, such as stress, emotions, and fatigue, for example.
Nevertheless, human factors are at the origin of numerous incidents or accidents that occur in aircraft. It is commonly accepted that pilot error or wrong application of a procedure can often be attributed, in full or in part, to an error made by the pilot. Such pilot error may result from one or more human parameters such as pilot stress, fatigue, emotions, or indeed work load when that becomes excessive.
Finally, such human factors, if they become excessive, and when combined with the complexity of certain stages of flight, can have a harmful influence on the pilot's awareness of the pilot's internal environment, such as managing aircraft controls and information, and also of the pilot's external environment, such as the terrain over which the aircraft is flying, the obstacles that might be encountered, and the weather. This harmful influence can have effects not only on the pertinence of decisions made by the pilot, but also on the actions the pilot performs, in particular on the quality of aircraft maneuvers.
All of the necessary information is delivered to the pilot by the MMI, and it is also via the MMI that the pilot can manage the information. Thus, when human factors become excessive, the pilot is under conditions that are prone to error generation and that can lead to an incident or indeed to an accident.
In particular, nowadays, accidents that can be attributed to pilot human factors constitute more than three-quarters of the accidents involving rotary wing aircraft.
At present, the MMI does not take human factors into account in real time, and more particularly it does not take account of the functional state of the pilot of the aircraft, even though solutions exist for attempting to anticipate them or to limit their consequences.
For example, the MMI has a function that makes it possible to detect and then to correct simple pilot errors, such as departure from a flight path or an information input error, in order to avoid such errors leading to an accident. However, that function does not enable multiple pilot errors to be corrected.
During training to become a pilot, pilot selection also makes it possible to test pilots for their abilities, in particular in terms of tolerating stress and in terms of the work load they can perform. Nevertheless, and in spite of the stress that taking an exam can generate, it is not possible to be certain that the character or the emotionality of pilots might not one day have a harmful effect on performing a particular maneuver or stage of flight.
Furthermore, the regular practice carried out by aircraft pilots, whether in flight or on a simulator, and also the additional training they receive, makes it possible, among other things, for pilots to automate the procedures that should be applied under various flight conditions and to improve their knowledge about various types of aircraft. Nevertheless, such practice and training cannot cover all possible situations exhaustively. Furthermore, the high cost of such practice and training can also limit the extent to which it can be used. In addition, the stress and fatigue encountered while practicing are always less than those that a pilot will encounter in a real situation.
Finally, simulations also make it possible to evaluate the work load to which a pilot can be subjected during various stages of flight in a variety of realistic missions. Nevertheless, an exhaustive list of all possible circumstances that might be encountered by a pilot, as a function of the pilot's level of knowledge and experience, cannot be evaluated with any certainty.