The wire strike protection system (WSPS) is a system of components designed to mitigate the risk of wire strikes while flying helicopters at nap-of-the-earth altitudes (a very low-altitude flight course used by military aircraft to avoid enemy detection and attack in a high-threat environment), as well as during takeoffs and landings. The system is mounted around the front of many military and some civilian helicopters. It appears as two guidance swords at the upper and lower front of the cabin protruding forward at 45°. In each of the inner corners to the cabin, a large fixed pair of scissors made of hardened steel is mounted whose opening angle is so small that a speedy or forced incoming steel cable is cut through. These swords are very often mistaken for radio antennas.
The entire system may include; 1. upper and lower cutter assemblies, 2. a non-electrically conductive abrasive strip wire scoring device along the centre of the divided windscreen, 3. windshield wiper protector frames to keep wires from hanging up on wiper motor shafts, and 4. some WSPS lower cutters have a break away tip in case of nose low ground impact.
The WSPS is designed to channel a wire or cable into the cable cutter to score and weaken it as it travels into the cutter assembly and "cut" a wire before it can entangle the rotor system. Test centres claim that in a single wire strike 90% survivability is achieved by using WSPS. The more wires encountered at a given time, the less likely WSPS will help the aircraft survive the encounter.
