These Soviet designed, Russian built Helicopters, in service with the Indian Navy, are presently the sole ship-borne dedicated surveillance platform.
A relatively recent acquisition, first bought in 1999, the India Navy operates 9 such Kamov Ka-31 'Helix' Helicopters as its early warning systems. Once airborne it can detect up to 40 targets simultaneously, that could be a mix of aerial and/or surface vessels. Plans are afoot to equip it with a buddy-buddy refuelling system, served by another helicopter, to extend its operational endurance [more details]. Besides Aircraft Carriers, currently the INS Viraat [R22] &, in future, INS Vikramaditya & the Vikrant-class of vessels, they are also operated from the Navy's Talwar-class of Frigates, built in Russia. With the induction of the INS Vikramaditya, the Navy's Ka-31 fleet would increase by another 5, as part of its Air complement, thus bringing their total number to 14.
Some pictures of the Kamov Helicopter, photographed by David-Osborn, during the Aero India 2005 Air show. Pretty visuals.
click on the image to view them in larger size
Also Read: Russia Delivers More Mi-17V5 Helicopters To India [New News With New Old Pictures]