These have been a familiar sight all over the world for a good part of nearly 50 years. Ever since taking to the skies in 1972 the Boeing E-3 Sentry has been the poster child of the Airborne Early Warning role and are still going strong today. So everybody knows about the plane with the overhead disk, but what does it do? Well, let me start by turning back the clock to the second world war. The Atlantic convoys had been under attack from Focke-Wulf FW-200 "Condor" Long range maritime patrol aircraft and the ships themselves didn't have radar on board to see when one was about to attack them, so the element of surprise was always with the Germans. The Radar technology of the time was developing rapidly and was getting to such a degree that planes such as the Condor pictured here could carry it along with them. In that guise radar was used to look out for the convoys at sea but it was also used in night fighters to scour out bombers in the blackest of nights and planes like the DeHavilland Mosquito used Radar in their night fighter role. But the Radar on board those planes had a relatively short range, long range radar required more real estate but as the losses in the Atlantic convoys began to mount, the high command of the RAF decided that fitting a long range radar to a plane would probably be the deciding factor to turn the tide in favor for the allies. They chose a proven and well liked plane as the perfect platform to try it out. The Vickers Wellington medium range bomber was a docile flyer and had a massive range. The bomb racks and armament was removed and powerful long range Radar fitted in its place. The idea was simple, when the message would come through that a convoy would leave from the USA headed for the UK, they would send in the Wellingtons to act as local radar stations which could look out for Condors and when spotted, they would send over a message to the escort aircraft carriers who would detach a fighter to engage the Condor. But then the Americans argued "Why not have those Radar planes on the aircraft carriers themselves?" which led to the development of the first dedicated airborne early warning plane. Again though, they based it on a proven and popular platform, the Grumman TBM Avenger, which thanks to its stable nature and long range made it perfect for that role. But the first TRUE Airborne Early Warning platform as we know it today was the Lockheed EC-121 Warning star which was a derivative of the famous Constellation airliner. The Radars of the Warning star were so refined that they not only could see enemy aircraft approaching but they also could tell what type of planes they were. In addition the Warning star was also used as a weather forecast platform being the first plane used by so called "Hurricane hunters" in that role it saved countless lives when after a hurricane alert was issued the people could be evacuated. And Warning stars were also used to connect US radio and TV station signals to US soldiers in Vietnam, basically serving as communications satellites before those were actually invented. The Warning star soldiered on from 1954 to the early eighties when all of them were replaced by E-3 Sentry's It is one thing to have an Airborne Early warning platform keeping an eye on things over land but the most use of them still is as that converted Vickers Wellington had been doing. To take watch over ships and warn them when a hostile attack is coming or when the weather starts to go for the worse and many times AEW platforms have saved the lives of many sailor. A Douglas A-1 Skyraider airborne early warning plane one of many different types used from carriers since the 1950's This particular one was used by the British Royal Navy, who used the type until it was replaced by the Locally built Fairey Gannet AEW. A Gannet on board the Carrier HMS Ark Royal in the 1970's about to be launched. With a Westland built Sikorsky CH-3 search and rescue helicopter standing by in case an emergency would happen. But during the seventies, a decision by the British government made people look up in morbid surprise: the Royal Navy would switch roles from being an active task force, its carriers would be taken out of service and its squadrons with planes and the kitchen sink included would be transferred to the RAF. In this new role all the active flying would be done by the RAF, what do you need a carrier force for? But because the Helicopter proved itself to be a vital component of maritime power and because ships STILL were vunrable to air attack, the Royal Navy got smaller carriers catered for vertical lift off planes such as the Hawker sea Harrier. In general, the carrier squadrons operated only three types of aircraft, they were the Fighter squadrons flying the Sea Harrier. Search and rescue flying the Westland Sea king And troop carrier transport squadrons flying the Westland Commando, which was a Sea King derivative but without its amphibious capabilities (Note no pontoons on its landing gear) So when during the early eighties, the Falklands war broke out, the high command was certain that although small, their maritime task force were up for the task but with several of their ships sunk by enemy air strikes discovered that they overlooked a tiny but vital detail. As this clip from that very conflict shows. As this reporter says, the two supply ships were carrying mobile radar units which were to be set up on the island, if they had actually unloaded those ships sooner, they would have seen the air attack coming. It was a painful reminder that there was a very good reason why Airborne Early Warning platforms exist in the first place. And during that time, the Royal Navy simply did NOT have a dedicated AEW platform which created a gaping hole in its defenses. After the war, they quickly rectified that with the Westland Sea King AEW. These days AEW has become so every day that nobody really takes note of a plane with a spinning disk on its roof anymore, and knowing what those planes actually do, it's a good feeling they're there. A Beriev A-50 "Mainstay" of the Indian Air Force. The Mainstay is the Russian built equivalent to the Boeing E-3 Sentry.