March 7, 2012: Israel has ordered two local airliners to stop using ATR 72 and ATR 42 twin prop transports because these models are too small to be fitted with anti-missile defenses that all Israeli air liners are equipped with. The ATR 72 is a 22 ton transport, while its predecessor, the ATR 42 is a very similar looking 18 ton aircraft. About a thousand of these aircraft have been built in the last three decades and most are still in service.
Israel is speeding up equipping its airliners with anti-missile systems. The recent collapse of the Kaddafi dictatorship in Libya allowed several Libyan arms depots to be looted, and Israel believes arms smugglers have moved shoulder fired anti-aircraft missiles to Gaza and sold them to Hamas (who would use them against Israeli aircraft). Military aircraft already have anti-missile defenses (which detect the launch of the missile then blinds its guidance system with a laser).
For its civilian airliners Israel is using the locally made C Music system. A typical airliner missile defense system has two components. First, there are six or more ultraviolet detection sensors (weighing 3-4 kg/6-9 pounds each) mounted on different parts of the aircraft to detect an approaching missile. These sensors are linked to a 3-5 kg (7-11 pound) 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 that uses a laser to confuse the missiles guidance system (that is homing in the heat of the aircraft's engines). The C-Music system weighs 50 kg (110 pounds).