Now many years ago, a YANKEE was "spooked" while on patrol.

The YANKEE fired a noise-maker and took off at flank speed.

The noise-maker was identified only post-event when a recording
was analyzed.

In real-time, the noise-maker was not recognized because the
YANKEE was making significantly more noise than the noise-maker.

I remember being a plotter at Arg. in the early 80’s. A Yankee was slowly creeping west out of the normal patrol box. We received a message saying a DD would go active at a certain time to let them know we knew they were there. Very soon after the given time, the Yankee made a high speed run back to the patrol box.