Towed Pinger Locator
The Phoenix Towed Pinger Locator (TPL) System provides the capability to detect and locate emergency relocation pingers on downed aircraft to a maximum depth of 6,000 msw anywhere in the world. Commercial aircraft pingers are mounted directly on the flight data and cockpit voice recorders, the recovery of which is critical to an accident investigation.
The system consists of the tow fish, tow cable, winch, hydraulic power unit, generator, and topside control console, although not all of these components are required on every mission. The tow fish carries a passive listening device for detecting pingers that automatically transmit an acoustic pulse. Most pingers transmit every second at 37.5 kHz, although the TPL can detect any pinger transmitting between 3.5 kHz and 50 kHz at any repetition rate.