June 16,2008: Germany has successfully tested launching anti-aircraft missile from a submerged submarine (U-33, a Type 212 equipped with Air Independent Propulsion). The IDAS (Interactive Defense and Attack system for Submarines) missile is 7.6 feet long, 180mm in diameter and weighs 260 pounds. It has a 29 pound warhead and a range of at least 15 kilometers. The main targets will be ASW (Anti-Submarine) helicopters and low flying ASW aircraft. Two IDAS missiles fit into a metal frame that in turn fits into a torpedo tube. The IDAS missiles take about a minute to reach the surface, ignite its rocket motor, spot any target within range and go after it. If the IDAS misses, an air bubble from the torpedo tube launch of the missile, will reach the surface, indicating where the sub is. At that point, the helicopter or aircraft can drop a torpedo. The sub has countermeasures for these torpedoes, but these devices are not guaranteed to work every time, or against every type of torpedo (some are better at detecting, and getting around, countermeasures.)

The sub commander would use IDAS if he calculated that a helicopter was likely to spot him with active sonar sonobouys or dipping sonar. IDAS can also be aimed at a surface ship (as in the bridge or a helicopter sitting on the platform at the rear of the ship. This is done using the fiber optic link, which can use used to designate a target. Otherwise, the missile uses its heat seeking sensor.

It will be two or three years before IDAS is available for use, but it's uncertain if any navy will buy them. The concept of anti-aircraft missiles for subs is several decades old, and never actually used. But it's possible, so new models keep showing up.