In the late 1950's decade, the US Navy had decided to assess, for the first time, a nuclear-powered attack submarine’s capability to detect and engage a naval task force at sea. The Task Group Alpha Hunter Killer Force of the US Atlantic Fleet was selected as the target for this assignment. The exercise area for the Group was off the Virginia coast, and the opposing submarine was the USS Skipjack (SSN 585), the first in a new class of nuclear-powered attack boats and considered the very latest and fastest in the US Navy.At the invitation of the USN, VX 10 sent trials aircraft Tracker 1507 and a detachment aboard the carrier USS Valley Forge in July 1959. Operating from the ship, the project aircraft started off by recording eight EER fixes on Skipjack in a 10-minute period when the submarine was at a depth of 150 feet and moving at up to 20 knots. This initial success showed that it was indeed possible to locate the “needle in the haystack”. The next day Tracker 1507 was conducting a MAD barrier in an area 25 miles ahead of and to port of the task group when a solid MAD contact was made with an underwater object. The position was immediately marked with a smoke float and fed into the ASWTNS, and the tracking started. The crew realized that it was imperative not to lose the MAD contact, especially if it was travelling at the high rate of speed expected of a nuclear attack submarine.
The pilot put the aircraft into a very tight left turn and brought it back on the task force side of the initial contact in less than 40 seconds. Almost immediately on rolling out of the turn, the submerged conning tower and some of the hull of a submarine could be clearly seen just below the surface. It was apparent from the separation of the smoke marker and the ASWTNS data that the submarine was travelling at a very high rate of speed. The contact was identified as Skipjack based on a comparison of photographs, through a previous sighting, and knowledge of the positions of two other submarines that were known to form part of the task group.
Since a report had been made to the flagship on the initial MAD contact, a follow-up report was sent as the second MAD contact was made, identifying the submarine with high probability as Skipjack and advising that it was heading rapidly in a southeastwardly direction towards the task force.
Tracking by MAD and ASWTNS had commenced as soon as the initial MAD contact was made. It was realized very quickly that both the MAD tracking, with its critical need for very steep turns and fast-rate manoeuvring, and the ASWTNS tracking operation with its complex array of display controls, would have to be done very quickly to ensure that contact with the submarine was maintained. The additional need for rapid and accurate EER ranges to assist in re-acquisition of the submarine when MAD contact was lost, meant that the entire crew had to work at maximum pace and in complete unison. With the at times wild gyrations of the aircraft, the magnetic manoeuvring noise was high, making it difficult to identify the “MAD marks” of a detection. Considerable skill was required in operating the equipment and in distinguishing real signals from the noise. A high level of expertise was demanded, and provided, with EER in getting dead accurate ranges for both fixing Skipjack (using range from a single buoy for MAD trapping) and maintaining the submarine’s track record at all times.
The operation of the ASWTNS so as to present an accurate picture of the tactical situation required masterful handling of the controls and great skill in collating and co-ordinating the incoming information, in anticipating Skipjack’s next move, and in directing the correct aircraft counter. This in turn called for very accurate flying, with skilled interpretation of the target position symbols on the ASWTNS display and at the same time with careful and accurate reference to the smoke floats that were dropped to mark the submarine’s latest position – all of this of course at altitudes below 100 feet where a second’s inattention could prove disastrous to the aircraft and crew.
During the tracking of Skipjack, 1507 would place either a helicopter or one of the screening destroyers in contact with the submarine and then move off to let them prosecute the contact. This was done in one of several ways: by passing a range and bearing, by orbiting the submarine’s position, or by dropping a smoke float. Without fail, the ship or helicopter would get an initial contact, and then almost as quickly lose it as the submarine manoeuvred away. The Tracker’s crew would then revert to the EER range/MAD trap, regain contact, track for awhile, and then again try to hand off the contact to one of the other participants.
In all, 1507 had Skipjack’s position accurately plotted for over 52 minutes of continuous operation, or about 47 minutes longer than this had ever been done before. The accuracy of this tracking was later verified when the aircraft and submarine track plots were compared and matched almost perfectly. This was most significant because the submarine had been unrestricted in both depth and speed. During the exercise it was found that while EER was giving excellent tracking information, it was a slower and more time-consuming process than MAD tracking. Accordingly, the latter was employed whenever possible.
The role assigned to the VX 10 project aircraft was detection and tracking only; no actual attack was carried out. Nonetheless, she continued to track Skipjack as she penetrated the task force’s destroyer screen and as she manoeuvred inside it doing simulated attacks on the destroyers. In several cases, 1507 was able to advise a destroyer of the submarine’s approach direction and its apparent intentions. After continuing to track Skipjack for awhile as she passed astern of the task force, 1507 returned to the Valley Forge.
The outcome of this exercise was that the Admiral in charge of the task force made determined recommendations for the most urgent procurement of the ASWTNS and its rapid introduction into USN service. In this he was undoubtedly given strong support by the Secretary of the Navy, who happened to be aboard the Valley Forge during the exercise and given a detailed briefing and demonstration of the ASWTNS by the VX 10 Project Team. As a result, the system was soon put into production and went into USN service in a little more than a year as AN/ASN-30. By contrast, the first Canadian set, designated AN/ASN-501, did not enter service for another five years!
Nonetheless, VX 10 could rightly claim to have carried out the first continuous real-time tracking of a submerged, unrestricted, high-speed, nuclear attack submarine. This was a historic achievement that advanced very significantly the anti-submarine warfare capabilities of both the United States and Canadian navies. It can be rightfully included among the revolutionary developments in early post-war ASW. As a postscript, it is worth pointing out that USS Skipjack, in the same year she matched wits with the RCN, “sank” every aircraft carrier involved in a major NATO exercise in the Mediterranean. One can readily predict what her success rate might have been had she been forced to again contend with ASWTNS-equipped Tracker 1507.
Feb 25/10