Perhaps the best summary of the usefulness of the radar pickets at Okinawa comes in a report prepared by the USN Navy Dept in Washington dated 20th July 1945 which was intended for wide circulation. A couple of comments are worth quoting from the early pages.
"Radar pickets have been an unqualified success in:
- Early radar reporting
- Fighter direction at extended distance from objective
- Shooting down enemy planes
- Breaking up enemy raids with gunfire
- Rescuing personnel from crashed planes"
"3. The need for radar pickets is fundamental. Facilities for early information of approaching enemy planes and their interception by CAP controlled by fighter direction ships from advanced positions must be provided in naval operations. This is true whether the operations involve the approach of a fast striking force toward a land objective, the pre-landing-day work of underwater demolition, minesweeping, bombardment, etc. of an amphibious support force, or a large-scale amphibious attack where massive naval forces must remain concentrated at the objective for an extended period of time.
4. The accomplishment of the important task of the advanced radar picket requires a sufficiency of properly equipped ships which are adequately supported by other surface craft and covered by CAP for as much of the time as possible. To be truly effective the picket must be capable of remaining on station."
Another interesting snippet in there concerns the Japanese use of Window up to 12th April in a largely unsuccessful attempt to jam the radar picket radars.
The USN had begun to use destroyers as radar pickets from Aug 1943 with the operation to occupy Baker Island. From then on their use in support of both amphibious landings and carrier task force protection increased. With the coming of the first organised kamikaze attacks on 25th Oct 1944 and the experience at Lingayen Gulf in Jan 1945 their importance increased still further. These events resulted in decisions to undertake numerous conversions of vessels and aircraft as dedicated radar pickets with extra radars and fighter direction personnel.
1. Gearing class destroyer conversions. Lost the forward set of TT to gain a new mast carrying an SP fighter director radar, YE aircraft homing beacon and various RCM equipment. Subsequently included in the AA upgrade programme losing the aft set of TT.
12 conversions post completion as destroyers of some of the earliest of the class were authorised Jan 1945. 6 of these were able to join TF38 off Japan before the cessation of hostilities with another 4 around PH and joining before the surrender ceremony. The final pair arrived in the Pacific before the end of 1945. Another 12 conversions were authorised in May 1945.
2. conversion of Buckley class DE 20 authorised & 7 completed as such from this programme (more conversions occurred post war). Conversion work began in June / July 1945 after they were no longer needed for Atlantic convoy escort duty. Also given AA refit with 5in guns and more Bofors.
3. submarine conversions. Planned on basis that unlike a surface ship they could submerge to escape if attacked. 24 conversions authorised with the first (Grouper, see photo link below, and Finback) being undertaken in July 1945.
4. The "flying picket" aka Airborne Early Warning. Project Cadillac I was on the verge of producing results when the war ended. An AN/APS-20 radar carried aloft in a TBM-3W Avenger. Problem with this was that the Avenger couldn't also carry a fighter director, just a radar operator, so the radar picture had to be transmitted back to a suitably equipped parent carrier via the "Bellhop" system. 27 conversions (later increased) were ordered in Nov 1944 as part of a crash programme. Trials were taking place on the night training carrier Ranger out of San Diego in May 1945 with the first operational carrier, Bunker Hill, trialling it in Oct. So possibly available for Operation Olympic.
To create a flying CIC to control fighters required a larger aircraft and the B-17 airframe was selected This became Cadillac II. A squadron to operate them was formed in July 1945 with the hope that it might be ready for Olympic. In the event, and with the post-war slowdown, the first of these PB-1W aircraft wasn't delivered until 5 Jan 1946.
The BPF adopted radar pickets but used a team comprising a cruiser and a destroyer pairing. The cruisers used had much better AIO (equivalent to USN CIC) and fighter direction facilities than was possible using The much smaller RN destroyers.
