For several decades low flying aircraft and helicopters have been equipped with defensive systems that detected approaching heat seeking missiles and automatically used countermeasures to make the missile ineffective. Now an Israeli firm is developing a similar system to deal with hostile gunfire from the ground. This would be especially useful for medical evacuation helicopters, which routinely fly into dangerous air space to fetch wounded troops.
These anti-gunfire systems would operate in a similar fashion to the anti-missiles equipment. These were designed as defenses against shoulder fired surface-to-air missiles (like the SAM-7 or Stinger) and are currently shifting from systems that use flares to those that use laser beams.
A typical anti-missile system has two components. First, there are four ultraviolet detection sensors (weighing about 2 kg/4.4 pounds each) mounted on different parts of the helicopter or aircraft to detect an approaching missile. These sensor are linked to a 3-5 kg computer that contains software for determining that the object is indeed a missile and where it is headed. The detection computer is hooked to a countermeasures system using either flares and chaff (strips of metal foil), or a laser, to confuse the missiles guidance system (that is homing in the heat of the helicopters engines.) The countermeasures component weighs 14-20 kg depending on type or model.
The anti-gunfire system would use a computer controlled machine-gun turret mounted underneath the aircraft to cause the people firing to stop, or at least ruin their aim. The sensors would not detect heat, but instead they would identify the light and the sound of firing or passing bullets. Such detectors have been used for over a decade on the ground for detecting snipers and have become quite effective. The key to making this anti-gunfire system work is the use of the aircraft machine-gun to deliver “suppressive” (make the shooter duck) fire to where the ground fire was coming from. The aircraft, even a helicopter, is moving quite fast so it helps a lot if suppressive fire can be quickly put on the ground shooter to make the shooting stop momentarily or ruin their aim. By the time the shooters on the ground recover their composure the helicopter is out of sight or much further away.