The U.S. Navy has ordered airborne anti-submarine warfare sensors from Raytheon under a new $33 million contract.

The AN/AQS-22 Airborne Low Frequency Sonar, or ALFS, is the primary undersea warfare sensor for the Navy's MH-60R multi-mission helicopter and is integrated with the aircraft's MK 54 lightweight torpedo.

"Access and safe passage on the world's oceans are critical to our global interests, economy and security," said Raytheon's Kevin Peppe, vice president of Integrated Defense Systems' Seapower Capability Systems business area. "ALFS' proven capabilities make it the U.S. Navy's airborne anti-submarine warfare sensor of choice, able to effectively sense and detect the otherwise unseen threat of enemy submarines."

The AFLS is an extended-range dipping sonar with multi-frequency operation for detection, tracking, localization, classification, acoustic intercept, underwater communication and environmental data collection. Raytheon began producing the system in 2002 and has so far delivered more than 130 ALFS units, including eight for the Royal Australian Navy under U.S. Navy Foreign Military Sale.

Raytheon said the new contract includes an option for additional systems which, if exercised, would being the contract's overall value to $98 million.

Details as to the number of units to be produced and their delivery schedule were not disclosed.