## 4 Conclusions  
The presented studies have been made at the airport facility. The analysis subject was the natural airfield pavements that protects flights in the immediate vicinity of the runway. The runway end safety areas and shoulders were evaluated. The CBR indicator for a layer 0-15 cm and 15-85 cm layers, as well as the strength of the turf layer to a 30 cm depth. The CBR values for the northern shoulder fluctuated around 10-15%, the smallest value was obtained at 5%, while the highest around 35%. For the southern shoulder, the situation was reconciled similarly, however the results higher than 20% was much less and lower and that is why the lower CBR indicator values were obtained. According to the requirements for the natural pavements at airport facilities, the results were far below the required values. Both eastern and western runway end safety areas were on the limit of requirements. As it is mentioned above, the minimum value was obtained at 5%, the highest was 20%. The exception was one point on western RESA, where a single CBR indicator for a 15-85 cm layer was 42%. The CBR indicator values obtained from the whole airport facility was homogeneous and satisfying from the point of researchers view. It was the basis to determine that the runway vicinity is a natural pavement with a close-up parameters all around its area. Average values of the CBR indicator for end safety areas was 0.50 for western site and 0.46 for the eastern site. In the case of shoulders, it was 0.47 for the northern site and 0.46 for southern site. In the case of the turf layer strength of the assessed natural pavements, the uniformity of the results was also at a satisfactory level. Only in five points the values were significantly lower than the obtained mean values for the whole element. The average values of the strength of the turf layer ranged around 0.9 MPa for the end safety areas and respectively 1.0 and 1.1 MPa for the northern and southern shoulder. Basing on the results of field tests with the use of the mathematical model of the APCI index, the APCI\({}_{\text{NN}}\) values were obtained at the level of 52 for the shoulders and respectively 50 and 54 for the eastern and western end safety areas. The values obtained on the basis of the criteria presented in the article are in the range for pavements with a sufficient technical condition. These are surfaces with deteriorations of low and medium harmfulness. Nevertheless, routine and repair maintenance procedures should be performed in order to increase the technical condition of the surface. Figure 18: APCI\({}_{\text{NN}}\) values for natural AFE pavements. Natural surfaces are an important element for the safety of air operations within the maneuvering area. They are a passive safety system and should be constantly inspected in terms of their technical condition. The requirements for natural surfaces in global aviation documents do not cover the issue in a comprehensive manner. The authors proposed a model of the APCINN index, which makes it possible to evaluate the technical condition of the natural airfield pavement in a complex manner based on the results of CBR tests for the 0-15 cm and 15-85 cm layer and the results of the turf layer strength. The calculated APCINN index gives clear information for the pavement manager about the pavement's technical condition. This makes it possible to take corrective actions as early as possible, which allows for savings throughout the entire life cycle of the facility. Management of airport pavements based on reliable and up-to-date information allows not only to save financial and human resources, but also ensures the safety of air operations at the right level. The presented APCINN model will be developed in the future with parameters obtained as a result of continuous assessment of natural pavements.