If Brian Williams was flying at 100 knots minimum 30 minutes (low end of reported "following") behind the helicopter that got hit, then he was over 50 miles from the helicopter that actually took fire. This is the difference between being t-boned, seeing the car in front of you get t-boned, and driving past the scene of an accident where someone got t-boned an hour afterwards. Taking fire is not something that you forget - you may misremember who else was there, but not if you were. The Costanza defense won't work here.