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US Navy Orders 20,000 Air Delivered Anti-Submarine AN/SSQ-125 Sonobuoys

U.S. Navy photo by Photographer Mate 1st Class John Collins (RELEAESD)

The US Navy is ordering 20,000 AN/SSQ-125 sonobuoys to manufacturers ERAPSCO Joint Venture, Sparto and Ultra Electronics (ULE) subsidiary USSI. The $71.8 Million contract annunced July 15th 2020 and expected to expire in July 2022 will help enhance the Navy’s anti-submarine fighting capabilities.

The ubiquitous parachute-dropped 36 lbs (16.3 kg) « A-sized » AN/SSQ-125 sonobuoy relies on the LAU-126/A Launch Container to be air-delivered at any altitude between 12 and 9144 meters (respectively 40 and 30,000 feet) at a speed varying between 0 and 370 knots.

Designed with a five years shelf life, the AN/SSQ-125 can hence be launched at a moment‘s notice from any rotary or fixed wing aircraft as well as by hand from the deck of a surface ship. The sonobuoy can recieve the command to scuttle after its mission is complete. Its LiSO2 battery life is not expected to last more than 8 hours.

Upon contact with saltwater, the sonobuoy will inflate a small float thanks to a supply of CO2 in order to position it at the sea’s surface. From that point on, sensors may be operated as the mission requires it to varying depths, strictly descending to four pre-selected depth position between 19.8 m (65 ft) and 152.4 m (500 ft).

The AN/SSQ-125 can be programmed prior to a mission to generate a wide variety of Radio Frequency waveforms from up to 96 channels. If already deployed, it can also receive commands to change its operating parameters.

Active Sonobuoy

According to its datasheet, the AN/SSQ-125 is best suited to operate as an active source in a multi-static sonobuoy field where it communicate with other sonobuoy on standard sonobuoy operating channels. By design the AN/SSQ-125 integrates with AN/SSQ-53F/G and AN/SSQ-101 (ADAR) passive sonobuoys. Its active functionnality allows it to generate accoustic energy signal (ping) that may be reflected-off, sometimes extremely difficult to detect, submarines. Although exceptionnally also able to receive ping signals (acting as a passive sonobuoy), the AN/SSQ-125 leaves that role to dedicated passive sonobuoys. The passive sonobuoys are dedicated to capturing the return signals from accoustic energy generated by the active sonobuoy, once reverberated by nearby submarine. The precise location, track, bearing, depth and speed data of a detected submarine can then be transmitted for tactical purpose. Because they do not emit any signal, passive sonobuoys are more difficult to detect than active sonobuoys.

For many reasons, the AN/SSQ-125 active sonobuoys are always ordered in very large quantities for a number of reasons : Being impossible to recover once deployed is one reason. Tactically because they must be deployed in good numbers in order to cover large areas where submarine ‘hunting’ is ongoing. Strategically submarine detection operations are taking place at every moment even in peacetime. And last because of their short mission life (less than 8 hours), they must be replaced by new units every few hours.

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