The Royal Netherlands Navy (RNLN) has successfully conducted trials of new low-frequency active-passive sonar (LFAPS) aboard its Karel Doorman-class or multipurpose (M–class) frigate, HMNS Van Amstel.

The testing was carried out as part of the operational evaluation (OPEVAL) trial of the system.

During the trial, the LFAPS demonstrated its abilities to mono-statically and bi-statically detect and track a diesel-electric submarine, in challenging environmental conditions, in littoral waters.

"The evaluation test was carried out along with a Walrus-class submarine and a NH-90 helicopter."

Based on the OPEVAL trial results, RNLN commander lieutenant-general Rob Verkerk tweeted: "Testing with Low Frequency Active Passive Sonar (LFAPS) on-board HMNS Van Amstel. Quantum Leap in the field of submarine warfare."

The evaluation test was carried out along with a Walrus-class submarine and a NH-90 helicopter, which was fitted with a low frequency, dipping sonar.

The Dutch Defence Materiel Organisation (DMO) received support from Ultra Electronics Maritime Systems in the development of LFAPS hardware, while the LFAPS processing software was developed by the Netherlands Organisation for Applied Scientific Research (TNO).

The 123m-long frigate Van Amstel (F831) is equipped to engage in anti-submarine and surface warfare activities.

The frigate is fitted with two quad launchers for the Boeing Harpoon block 1C anti-ship missile, which has an active radar seeker with inertial mid-course guidance, a 220kg warhead and a range of 120km.

In March this year, Van Amstel was assigned to Standing Nato Maritime Group 2 (SNMG2) for deployment in the Aegean Sea.