When driving the F40PH-3C with all safety systems enabled, sometimes a penalty application of the brakes will start seemingly without cause. The application does not appear related to any change in speed limit, signal indication, overspeeding, or alerter, and there are no warning lights or audible alarms that would indicate a normal safety system activation. Pressing the alerter or ACSES acknowledge buttons with or without the brake handle in the suppression position do not stop the penalty activation. Recovery is possible after the train has stopped by putting the reverser into neutral and pressing the acknowledge buttons. I have not had the issue occur consistently, although when it does occur it seems to occur around the same sections of track each time, and at several points during the same service.