They did more research and learned that another copter had crashed in the area in October of 1964, 11 years before Helo 66. It was on a nighttime training mission when it went into the water with four people aboard. All were rescued.
It, too, was a Sea King, but a different model. One of the differences was the length of the sonar cable. Helo 66 carried a 500-foot cable; the 1964 copter would have had a 250-foot one.
In August, Eldridge went down for a second look at the wreckage with another diver, Ben Lair. (Stalter was out of town.) They took measurements of the cable spool to calculate an approximate length of the cable. They came up with 250 feet.
Mystery solved. It wasn’t Helo 66 — a disappointment, Eldridge said — but possibly the Sea King that had crashed 11 years earlier.
Except when Eldridge shared his findings with a military-aviation expert, the expert raised doubts. If the wreckage was from 1964, the copter would be all grey in color, the expert noted. The one on the ocean floor had pieces that are white. The Navy had changed the color scheme from all-gray to gray-and-white in 1967.
Plunging back into research, Stalter found news clippings that mentioned a third Sea King crash off the San Diego coast. It went down on Sept. 3, 1968, during a test flight. The helicopter had just gone through a major overhaul at North Island. Two crew members were rescued by a nearby fishing boat. A third aviator was never found.
The location of the crash, about 10 miles off Imperial Beach, made it a possible match for the wreckage. The date fit the grey-and-white color scheme, too.
When Eldridge had made his second dive to the copter, he took a scrub brush to clear mud off pieces of the debris. On the tail section, he found black tail code letters identifying which aircraft carrier group the helicopter was part of.
One of the letters was clearly an “N.” The second letter was only partially visible because of damage from the crash. But it didn’t appear to be an “E,” which Helo 66 would have had, and it didn’t look like a “U,” which would have matched the 1964 Sea King.