Strong encryption, electronic counter-countermeasures, and mechanisms, such as burst transmission to reduce the chance of being located all play a role.
Passive listening is used when the tracking system is not emitting any energy, such as with underwater systems, with electronic counter countermeasures, and with projectile sensors.
Trail patronage is counted using electronic counters, with the numbers at four remote locations extrapolated to estimate the whole trail usage, as not all riders ride the full trail.
The lack of dedicated pathfinder units also caused navigational problems, as the few aircraft employed in this role were more at risk from electronic counter-measures and fighter interception.
