Abstract Designing exploitation in seams in surroundings of strongly methane bearing seam assumes particular importance in conditions of the growing concentration of output. While planning exploitation, calculations results of predictions of methane emission to longwalls form a basis for selection of a mode of ventilation scope of utilized prevention, including methane drainage, as well as planned volume of coal output. Performed in the article, systematic analysis of methane hazard in longwall N-12 in seam 329/1, 329/1-2 in ‘Krupiński’ Coal Mine, in which on 5.05.2011 took place methane ignition, allowed to determine factors forming methane hazard in this longwall while taking into consideration location of longwall parcel relative to previous mining in this seam. Occurring discrepancies between total amount of methane emitted to longwall N-12 and forecast value indicate circumstances of additional inflow of methane from outside of its environment. Confirmation of such methane flow are results of calculations of distribution of the field of aerodynamic potentials in workings contouring mined out longwall N-14 and mining of longwall N-12, as well as, being a relevant particularity, results of methane bearing determination on coal pillar separating post-exploitation goaf of both longwalls. The article emphasizes the necessity of taking into account, at the stage of designing longwalls, ventilation conditions and the influence of the field of aerodynamic potentials on the possibility of goaf gases flow which may contribute to the increase of methane hazard.