February 1996. Actually there wasn't a loss of air pressure per say. There was a blockage in the train line which did not allow the air to reach the entire length of the train. It was never fully determined what caused the blockage. If someone had of disconnected an air hose then the train would of went into emergency. If someone had shut off an angle cock (air valve) then the train would not have been able to move because the brakes would not have released (this train had stopped at Summit before the runaway). So it was neither of those two. Also the cause was not that the FRED wasn't functioning properly. What was determined was that the FRED wasn't activated for two-way operation when the train left Barstow. If it had of been then an emergency brake application could have been applied at the rear of the train (via the FRED) but at the time that was not a requirement and only some FRED's at the time had that function. Nowadays it is a FRA requirement to have that type of FRED in heavy grade territory and the two-way emergency function has to be tested before leaving an initial terminal. Again the actual cause for the runaway was never fully determined and only a speculation was given.
But as was said the fencing and lights were erected for fear of someone tampering with a train stopped at Summit.
Thanks for that full explanation. I couldn't remember all of the details, but I knew that a FRED and finger's pointing at the rail fans was involved, thus the security fencing.