Applying formulas (14)- (17) to IPSs that are found with proposed differentiated method (which uses mistakes hazards sum distribution), it is possible to find the following opinions marginality criterion: It is calculated that marginal thoughts are expressed by 10 ATC experts, which is shown in Figure 2 where ≻ m A À shows the prevalence of one mistake hazard level over another mistake in GrPS combined with m A ATC expert opinions. It is found that correspondent correlation coefficient value is equal to W A ¼ 0:7 for m A subgroup. It satisfies the requirements of criterion (13) and is statistically acceptable because χ 2 A ¼ 377, 743 >>χ 2 26, α¼1% ¼ 45, 642 . Thus GrPS found for m A ¼ 27 subgroup actually can be used for flight safety management measures and ATC professional training.
Further filtering and analysis could be performed with the same proposed method for m B ¼ m À m A ¼ 10 ATC subgroup as is shown in Table 1. Figure 3 clearly shows the main steps of presented multistep algorithm. It is clear that after m A subgroup separation, it was impossible to find any other subgroups with internal opinions consistency. That is the reason for these 10 ATCs to be under increased attention during prevention of negative HF influence upon FS.
Finally it is worth mentioning the positive influence of the procedure on the ATC experts' personal traits. Since during the survey, they had to imagine and compare 210 pairs of mistakes with an attempt to determine their hazard levels.

### Language ###
English

### Assessment ###
A query about the specific number of ATC experts expressing marginal thoughts according to the text

### Query ###
Tell me how many air traffic controllers have been identified as having marginal opinions in their assessments.
Tell me how many air traffic controllers have been identified as having marginal opinions in their assessments.