The incident occurred at about 7:30 pm.
"The aircraft had got airborne 06:35 pm but developed critical engine malfunction and a controlled ditching was undertaken at sea. Other IN and ICG Aircraft flying in the vicinity were immediately diverted to search for the ditched aircraft,"a Navy release said.
The wreckage has not yet been sighted. Aerial search by IN Dornier and ALH is in progress, it said.
Meanwhile ships at sea with divers and other necessary equipment have also been diverted to the crash area which has a depth of 24 metres to locate and recover the RPA.
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To put it in perspective, Airbus, the world's largest
aircraft-maker, has made only 10,000 planes so far.
The aircraft on the world tour has two Pratt & Whitney piston engines, Agullo said, adding that it has flown 74,500 hours. Engines of this make have to be changed after every 1200 hours, he said.
The DC-3 was also the first plane to complete the US east-west journey with just one stop. Out of the 16,000 DC-3 built, 10,000 were in the US, 487 in Japan and the rest in Russia.
The Breitling DC-3 World Tour will end in Geneva in September after covering 24,000 nautical miles.
On Wednesday the plane will fly off to Chittagong in Bangladesh, from where it will head to Bangkok, Singapore, Hong Kong, China and Japan.
It will be stationed in Japan for a month before heading for the west coast of the US. In Tokyo, the plane will offer a joy ride to the child victims of the 2013 tsunami.
Civil DC-3 production stopped in 1942 with 607 aircraft made. However, the production of its military derivative, the C-47 Skytrain (designated as Dakota by the UK's Royal Air Force), and the Russian and Japanese versions continued till 1950.