On the recordMarch 27, 2017
Of 382 cases adjudicated by the PET so far, 130 have involved some form of contamination, 114 involved an ECS component failure, 91 involved human factors, 50 involved an OBOGS component failure, 13 involved a breathing gas delivery component failure, and 76 were inconclusive or involved another aircraft system failure.
Source
congress.gov




