**Abstract** : This paper will show how frequency diversity improves the availability of accurate navigation solution of GNSS receivers, in the case of aeronautical applications for instance. Therefore, frequency diversity is a mean to mitigate jamming and interferences, to consider among others. It is very important for civil aviation to handle a probabilistic theory related to involuntary jamming of GNSS receivers, with and without the use of frequency diversity. As a preliminary hypothesis, we assume that the GNSS link budgets has been equally balanced for each considered band Bi, even if a band is provided with more interferers than an other. In this later case, this would mean that the GNSS power is higher in the band provided with more interferers. This first assumption can be translated in probabilistic terms. The second assumption made is a jamming probability much smaller than 1. These assumptions are used to derive: - The probability to lose the navigation solution of a monosystem dual frequency receiver, like a L1/L5 GPS or GALILEO receiver. - The probability to lose the navigation solution of a monosystem tri-frequency receiver, like a L1/L2/L5 GPS receiver or a GALILEO E5a/E5b/L1 or E5b/E6/L1 receiver. An application is computed, for a jamming probability of 1/10000 during a full flight. In such a case, the probability to loose the dual frequency navigation function is 15000 times lower in the case of a tri-frequency monosystem receiver instead of a dual frequency monosystem receiver, and this makes this event an improbable case. Intermediate conclusions has been drawn : Frequency diversity has an enormous potential as an interference mitigation mean, which can be at least as efficient as beam forming reception GNSS antennas. - To have an efficient ionospheric correction, the availability of two frequencies among a single system is necessary - The use of L1C/A, L2C, and L5 is interesting for a more robust GPS receiver. The L2C channel can be considered as a backup ; L2C is the mitigation mean. - The use of E5a, E5b, and L1BOC(1,1) is also very interesting for an aeronautic GALILEO receiver, since all these 3 bands are ARNS. The E6 Galileo frequency (provided with integrity) could even be a backup to one E5 signal componant if necessary. The capabability to process ionospheric corrections using only E5a and E5b GALILEO signal componants will be discussed, thanks to code/carrier divergence observations. The paper will also show that E5b C/No degradation due to military radar spurious is low and acceptable.