The rescue submarine and its remotely operated robotic vehicle (ROV) officially replaces the former system, which rescued seven Russians in August 2005 trapped in a mini-submarine entangled in cables.
The new system is able to travel faster, dive deeper and carry more sophisticated equipment than the previous craft.
It comprises a 30ft-long manned rescue vessel and the separate unmanned ROV. The system, based at the Royal Navy submarine base at Faslane, near Helensburgh, will respond to emergencies within hours and take part in full rescues within three days.
Commander Steve Birchall, project leader, said: "The new system has been progressively assembled at Faslane over the past 18 months by the Royal Navy and Rolls-Royce team.
"When a submarine gets into a distress, it will alert its navy. The distress call will then come through to the UK fleet headquarters, Northwood in London, which has operational control of the system. It would mobilise the rescue system within two hours.
"A small group of key people would be called out and they would be looking to get the ROV on the road within six hours, but in trials we have managed it in half that time."
The Defence Procurement Agency said the new system, the most advanced in the world, would enable the Scottish-based rescue team to reach submarines in distress at greater depths than before.
Within three hours of an emergency call, its three-strong crew will identify and track suitable vessels in the rescue area that could act as a mother ship for the craft. The ROV is likely to be flown from Prestwick airport by military transport aircraft.
The entire system requires a convoy of 24 lorries for transportation and four aircraft.
The ROV will reach the scene within 56 hours and find the stricken submarine by homing in on its tracking beacon. The probe will check for signs of life by tapping on the hull and can dock with the submarine to establish communication and provide emergency supplies to survivors through its escape hatch.
Among the ROV's tools is a video camera, and it will also be able to measure air quality within the stricken sub and remove debris and cables around its hull which could hamper rescue attempts. The submarine rescue vehicle will follow within three days and be able to dive to more than 2,000ft – nearly 400ft deeper than the previous rescue craft. The 29-tonne submarine, together with equipment to launch and recover it, will be carried to the scene by its chosen mother ship.
Using battery-powered motors, the three-person crew will manoeuvre the rescue craft into position, locating the submarine's escape hatch through a viewing port with powerful spotlights. It will dock with the escape hatch and can bring a crew of up to 150 personnel to the surface, 15 at a time.
Survivors will be placed in decompression units to prevent them contracting the "bends", a potentially fatal condition.
The team's commander is confident that when called upon, it will do its duty.
He said: "Submarines are very strong, but when something does go wrong you need to get out there very quickly.
"The guys are trained and there is never any doubt that if we mobilise, we will succeed. The guys believe in their kit and have no doubt that it will perform."
© 2008 - The Scotsman