G.S. Nakhmanson - Dr. Sc. (Eng.), Professor, Military Educational and Scientific Center «Zhukovsky-Gagarin Air Force Academy» (Voronezh). E-mail: kig28@mail.ru
D.V. Buchnev - Post-graduate Student, Military Educational and Scientific Center «Zhukovsky-Gagarin Air Force Academy» (Voronezh). E-mail: d_buch@list.ru
A.V. Suslin - Ph. D. (Eng.), Lecturer, Military Educational and Scientific Center «Zhukovsky-Gagarin Air Force Academy» (Voronezh). E-mail: 510323@bk.ru

Aircraft crews receive information concerning push down and aircraft position relative to runway during landing by means of the ground controlled approach systems. The glide slope angle is relatively small (2°40'−3°15'). Therefore, the vertical profile of the atmospheric refractive index may influence the glideslope axes antennas radiation propagation paths of the ground controlled approach systems. Analytical expressions for the radiation propagation tracing and its possible refraction deviations using temperature-wind sounding information as a source data are derived. The results are represented by calculation of possible radiation propagation paths refraction deviations of the glideslope axes antennas in Voronezh on 24.05.2014, 30.06.2014, 24.07.2014. Curves of possible deviations from calculated radiation propagation paths against distance between point projection on the propagation path to the ground and ground controlled approach system position for radiation angles of 2°40' and 3°15' are presented. Numerical values of these deviations in angle values within the vertical plane and deviations in length values for different distanced are displayed. It is revealed that the possible radiation propagation paths deviations of the ground controlled approach systems glideslope antennas caused by refraction may be above permissible limits. Therefore, they may enlarge aircraft positioning errors.

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