Mil-LOK Hoist hook

NSN:  4030-01-605-5110

LSC Part # 412




The Lifesaving Systems Mil-LOK  hook  is an auto-locking hoist hook built and tested to Military Specification MEETS MIL-DTL-23599 and has been field proven by the French Navy and the United States Air Force Osprey Program since 2010.

The Mil-LOK hook defaults to the auto-lock mode. The gate and safety latch are easily functioned by a single gloved or bare hand. When the yellow latch knob is rotate up and just out of the detent using the thumb, the gate can be easily pulled back with opposing fingers. When released the spring-assisted gate and safety latch automatically return to the locked position preventing unintentional load release or dynamic rollout from any sized ring or attachment hardware.

In certain high-risk operations such as combat SAR or when hoisting in high sea states to vessels, the overall safety posture of operations may be improved when the gate is temporarily unlocked, allowing for rapid hookup or release. When necessary, and in consideration of all variables of the hoist operation, advanced operators use the unlocked gate to their advantage by ensuring the lock mechanism does not hinder their entry or exit from the hook in any way.  The Mil-LOK incorporates this ability with the following safety features built into the device:

  • Disengagement of the lock requires the deliberate two-hand manipulation of a trained operator. This feature cannot be accidentally engaged.
  • Re-locking the gate is done with a single-hand push of a release button that immediately returns the hook to the auto-locking mode. (The device may be inadvertently locked – but never inadvertently unlocked)
  • Red is displayed on the gate face anytime the auto-locking feature is disabled making the condition easily identifiable by all crew members.

Another safety aspect of the Mil-LOK design is its inherent resistance to dynamic rollout even when the auto-lock is disengaged. The distance between the hook beak and the bottom of the gate was designed to defeat the geometry of most lifting rings on common rescue gear.

Operational Use

The Mil-LOK hook is the only hoist hook in use by the U.S. Armed Forces that meets the current MIL-STD-23599B specification. In addition to all of the strength and material standards, the Mil-LOK hook simply cannot be inadvertently unlocked.  This feature was key when the French Navy chose the hook for their operators who needed a safe way to disengage the auto-lock for initial deployment to vessels at sea.

The United States Air force has been using the Mil-LOK on their V-22 Ospreys for combat search and rescue operations without issue since late 2010. The operators requested a slight modification to the size of the tabs on the locking gate.  Lifesaving Systems modified the tooling and updated all of the hooks to incorporate the change.

3D rendering of Mil-LOK Gate with extended tabs.







U.S. Air Force Staff Sgt. Casey Spang, 20th Special Operations Squadron flight engineer, practices a harnessed hoist lift from a CV-22 Osprey while flying over Melrose Air Force Range, NM, July 5, 2012.


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