Analysis of the phenomena related to the satellite signal used operationally in civil aviation is not possible without a model analysis. Experimenting on an actual flight operation can lead to dramatic effects. Therefore, numerous attempts are made to study the signal and the processes taking place in satellite systems during operation, which have a potential impact on its disturbance. At the same time, the interest in the implementation of satellite techniques to various areas of air traffic is clearly visible. There is also a noticeable number of studies carried out on both the operational parameters of satellite systems and the satellite signal itself. The aim of such tests is to achieve the best possible results, inter alia, in terms of signal integrity. It also seems of key importance that the atmophere condition in any area of ​​aviation should not be underestimated due to its extensive impact. It has been proven, in the world literature, that the ionospheric factor is seriously limiting the operational use of the satellite navigation signal. For aviation, it remains a particularly important aspect to provide information about the integrity of the data transmitted to the user. The aim of the article is therefore to check whether the ionospheric factor, determined by solar activity, significantly affects the integrity of the satellite signal. For this purpose, a fuzzy logic approach will be used. Literature sources define two approaches to fuzzy control - descriptive and prescriptive. The first is based on the expert knowledge of the operator who knows from experience how to control the process. This is a traditional approach, not based on an existing model. The second approach assumes the existence of a stochastic or deterministic model and determines how to optimally control it. In the article, the traditional approach is closer to research. The model of the process determining the output (satellite signal integrity) as a function of the input (solar activity) is unknown. This means that this process is a black box. However, knowledge is available on how to control the process well, i.e. what control to choose for the current output.