Inside Marco's Missile Tracking Station: High-Tech Operations

No missiles were ever launched from Marco Island’s Site D-7. So, what exactly happened behind the security fence at the old tracking station near Caxambas?

The answer is that Marco's station was built to collect information rather than launch weapons. Every missile test over the Gulf of Mexico produced enormous amounts of data, and without stations like Marco, much of that information would simply have been lost. While the launch crew at Eglin Air Force Base received most of the attention, the technicians working hundreds of miles down range quietly recorded the results that determined whether a missile had succeeded or failed.

By the time the station became fully operational, approximately fifty employees worked at the Marco Site D-7. Most were electronic technicians employed by the Vitro Corporation under contract to the Air Force. Their jobs required far more than simply watching radar screens. Every missile test demanded that dozens of electronic systems operate together with split-second precision while communicating continuously with the other tracking stations scattered along Florida's Gulf Coast.

Getting the station ready for those missions was no small task. Before Vitro assumed responsibility for operating the range, the Federal Electric Corporation had built much of the facility. Unfortunately, according to Clifford “Randy” Gilmore, Site Manager in 1960, the electrical wiring had been installed with little consistency and almost no engineering drawings. Randy and a small maintenance team of only five or six technicians inherited what one might politely describe as an electrical puzzle. Before long they began recruiting experienced technicians, many transferring from Eglin Air Force Base in Florida’s Panhandle, to reorganize the wiring and prepare the station for full operation. By the time regular missions began, the staff on Marco had grown into the fifty-person team that kept Site D-7 running around the clock.

The Eglin Gulf Test Range was a massive, highly classified overwater military testing ground, stretching across the eastern portion of the Gulf of Mexico. Approximately 120,000 square miles of overwater airspace where missiles were tracked, measured, communicated with, and control systems were tested.

Before every launch, the “Theater” had to be “Cleared” of two major problems: 

1.  The flight problem of commercial airline routes and private planes – the FAA assisted by closing down large blocks of airspace hours in advance, and

2. The surface problem: commercial fishing boats, shrimp trawlers, cargo ships entering the drop zones. Eglin used its own fleet of sea surveillance vessels with radar and low-flying search planes to spot vessels, alerting them via radio. The impact area (where missiles were expected to drop into the Gulf) had to be entirely clear before the countdown for the missile launch started.      

Occasionally, the targets used for the BOMARC missile tests were obsolete Mace and Matador missiles launched from a site in Venice, Florida. But more often the primary targets were not missiles but usually aircraft. The Air Force converted former military airplanes into remotely controlled drones, including QB-47 bombers and later QF-80 and QF-102 fighter aircraft (The “B” and “F” standing for Bomber and Fighter, with the “Q” standing for Drone). These aircraft were flown from remote control consoles located in north Florida at Santa Rosa Island and Port St. Joe. The pilots, who were professionals at flying these planes, sat in front of instrument panels nearly identical to those found inside an actual cockpit. Through radio-frequency communications, they could guide and fly the drones (actual unmanned bombers and fighter planes) hundreds of miles across the Gulf while the pilots never left the ground. Randy Gilmore recalls that when he left Marco in November of 1962 and was the Data Systems Chief Range Instrumentation Director and Manager of the entire test range, a Lt. Colonel friend of his, the Chief drone pilot, would drive out to a radar site in north Florida and “fly drones all over the Test Range” while Randy drove to another location 15 miles away and “controlled those missions as the Range Instrumentation Director.” 

What exactly were these technicians tracking as the BOMARC missile raced toward its target? Contrary to what many people might expect, the objective, unless the target was another missile, was usually not a direct hit. These drones represented a considerable investment, and destroying one during every test would have been extremely expensive. Instead, engineers programmed the missile to pass as close as possible to the target aircraft. The most important measurement became what engineers called the “miss distance." If the missile passed within the required distance at the correct speed and altitude, the test was considered successful. The BOMARC missiles were either detonated by a Range Safety Officer or, in most cases, plunged into the waters of the Gulf of Mexico.   

That required extraordinarily accurate tracking equipment. The Marco Site D-7 originally operated with two mobile radar units, but these were eventually replaced by the fixed-based FPS-16 radar manufactured by RCA. The newer radar proved to be much more accurate and considerably easier to maintain. As computers became increasingly important during the late 1950s and early 1960s, the FPS-16 radar was modified for computer control, representing one of the many ways the Air Force was gradually moving from analog electronics into the digital age. Because not every piece of equipment evolved at the same pace, technicians also relied upon analog-to-digital and digital-to-analog converters so that older and newer systems could communicate with one another.

Radar alone, however, could not tell the entire story. Every missile and drone continuously transmitted telemetry, a steady stream of electronic information reporting the health of onboard systems (altitude, speed, fuel consumption) throughout the flight. At the same time, Marco personnel monitored atmospheric conditions over the Gulf. Why was this necessary? Radar signals do not always travel in perfectly straight lines. Layers of temperature and humidity above the water can bend radio waves, sometimes causing targets to appear slightly above or below their true position. To compensate, technicians regularly launched weather balloons and radiosondes to measure the atmosphere's refractive conditions, allowing engineers at Eglin to correct their radar calculations and maintain accurate tracking.

Collecting all of this information would have meant little if it could not be delivered back to Eglin immediately. The Gulf Test Range functioned because every station communicated continuously with every other station. Most of these connections relied upon microwave relay towers, but the longest stretches across open water presented a different challenge. The solution was a remarkable technology known as tropospheric scatter, often shortened to "tropo-scatter." By directing powerful radio signals into the lower atmosphere, engineers could send information beyond the horizon without relying on vulnerable undersea cables. The system connected Port St. Joe with Anclote Point and linked Marco Island directly with Cudjoe Key in the lower Keys, allowing time, position, telemetry, and voice communications to move instantly throughout the range.

Back at Eglin's Central Control Facility, all of the information collected at Marco appeared on large vertical plotting boards where Range Safety Officers followed each mission second by second until the missile dove into the Gulf. If a missile ever malfunctioned and turned toward the Florida coastline, the officer had only seconds to react. With the flip of a switch, an encrypted destruct command could be transmitted instantly to the missile, ending the flight before it endangered people on the ground.

Although the Vitro technicians operated the equipment on Marco’s Site D-7, they were also one part of a much larger national defense system. Information gathered at Site D-7 became part of the Semi-Automatic Ground Environment, better known as SAGE, an enormous NORAD command air-defense network headquartered in Montgomery, Alabama. During what was referred to as the “command guidance” stage, SAGE radar tracked both the missile shot from Eglin (using a ramjet engine to power it) and the target and sent steering commands to the BOMARC’s onboard guidance equipment via radio. When the missile was near the target, “terminal guidance” was handled by the BOMARC’s own active radar homing system, which locked into the incoming aircraft or missile. The same technology that evaluated missile tests also strengthened America's ability to detect and intercept hostile aircraft during one of the tensest periods of the Cold War.

When the day's testing was finished, life at Site D-7 returned to a more relaxed pace. Most of the employees drove home to Naples, while a few lived nearby in Goodland. The station even fielded a softball team where Randy was the catcher, but many weekends were spent fishing the Ten Thousand Islands or enjoying Marco's quiet waterfront long before the island became a major resort community.

Today, little remains to remind visitors of the remarkable work once performed there. Yet behind the fences at Site D-7, fifty technicians quietly operated one of the most sophisticated electronic facilities in Southwest Florida. Their work never appeared in newspaper headlines, but every successful missile test over the Gulf depended upon the information they gathered and transmitted back to Eglin Air Force Base.

To be continued … Part Three: “Hurricane Donna and the End of Marco’s Missile Tracking Station”