## 1 Introduction  
Heterogeneous wind fields such as turbulence or wind gusts cause changes in local aerodynamic forces and momentums, affecting aircraft structure and which can be a causative factor of air operation safety. According to the International Civil Aviation Organisation, the change in headwind of 15 kt (7.6 m/s) or more at an altitude below 1600 ft (or 500 m) at a 3 nautical mile (5000 m) radius from the runway threshold is classified as significant low-level wind shear (ICAO, ang. International Civil Aviation Organization, 2005) [1]. Wind shear happening on a meteorological microscale (effective range less than few nautical miles) is characteristic to airfields located on islands or in mountainous areas, affecting the safety of take-off and approach phases during which the aircraft operatesclose to critical angles of attack [2; 3; 4; 5]. Sudden changes in both direction and wind speed are also results of meteorological phenomena occurring on a synoptical scale (squall lines, atmospheric fronts, and inversions). The danger can be posed by the phenomenon known as the clear air turbulence (CAT) [6], appearing in the close proximity of jet streams in a clear atmosphere. They emerge as a result of differences in wind speed at various altitudes, mainly flight levels which correspond with a narrow spectrum of available airspeeds--the coffin corner. In such a scenario, the stall speed is in proximity to the critical Mach speed for airliners. The wind shear prognosis is challenging and not always possible to be accomplished due to the local and time-limited characteristic of this phenomenon. The dynamic development of civil aviation has brought the development of warning systems protecting against wind shear. Because of high maintenance costs, advanced airfield systems detecting wind shear such as the low level wind shear alert system (LLWAS) and terminal doppler weather radar (TDWR or SODAR) [7] are being used only by the minority of the most important airports around the world. Most airports accomplish standard measurements of wind direction and speed as well as gusts with the use of anemometers localised in the adequate runway area. An accurate measurement is able to be obtained during the last seconds of approach and on flare and touchdown. Because of that, for a majority of flight phases and considering automatic steering systems, the most important thing is the accuracy of measurement accomplished by the on-board systems. The on-board wind shear warning systems \"WSWS\" can be divided into reactive wind shear systems \"RWS\" using direct measurements of flight parameters and predictive wind shear systems \"PWS\", working on the principle of prediction of wind shear preceding the aircraft by 10-40 s.  
In the last years, main jet aircraft producers have been focused on the development of PWS. In one of the latest constructions--Boeing 787--the gust suppression system was used. During the automatic phase of flight, it utilizes the symmetric deflection of the flaperons and elevators to alleviate gust acceleration. Lateral gust suppression improves ride quality by automatic application of discrete yaw commands in response to lateral gusts and turbulence [8]. The research on widening the functionality of existing systems is based upon improvement of the ability of foreseeing future loads as a means of supplying updated data for an anticipated load. The use of the LIDAR [9; 10] sensor is considered as an on-board solution. It works on the principle of laser beams instead of microwaves, allowing one to obtain data about radial wind velocity at various distances. The compensation of wind gusts is accomplished through a change in aerodynamic loads. Pitching the aircraft is the most effective way of achieving the above-mentioned goal. Another way is through the use of steering surfaces, e.g., ailerons and spoilers, or even through direct lift control DLC [9].