Radar operators at the Navy's long-range tracking facility here spotted the small twin-engine Cessna soon after it left Colombia one night last April and watched it head northwest across the Caribbean on a suspicious course.
Mexican police, notified by U.S. authorities that the aircraft appeared to be heading to the Yucatan Peninsula, were in position to witness the drop of 900 kilograms of cocaine, seize the shipment and make several arrests. The Cessna, unaware it had been discovered, was allowed to fly back to Colombia, still under the gaze of naval trackers who helped guide Colombian officials to the plane's jungle landing strip.
The episode highlights a new use for a military radar system intended originally to monitor Soviet bombers. With Moscow no longer the worry it once was, the Pentagon thinks it has found a way of salvaging this elaborate multimillion-dollar surveillance network by targeting drug-trafficking planes instead.
As overall U.S. military spending on drug smuggling declines, defense officials say the powerful spying system installed here in the Virginia countryside is a more cost-effective way of keeping tabs on drug-ferrying planes than the network of regional ground stations and balloons on which the United States has relied.
But some law enforcement officials, noting several operational problems with the new system and a decline in air trafficking that began before the system's introduction, are not yet sure the super radar is worth the expense.
At a set-up cost of about $14 million each and annual operating expenses per facility of $12 million to $14 million, the system is not cheap. Even with such high-tech wizardry, drug enforcement authorities end up seizing relatively few planes.
In a typical three-month period, radar detects about 20,000 aircraft traversing the Caribbean, according to figures supplied by the U.S. Atlantic Command. Only 45 of those flights are determined to be "suspect," and only about half are interdicted.
The tiny percentage of captures is a frustration for many involved in the effort, including Cmdr. Bob Hillery, who heads Fleet Surveillance Support Command, which operates the system.
"Surveillance is only part of the problem," he said. "There also aren't enough players to make the arrests."
The Defense Department is establishing a tracking installation in Texas similar to the one here and has plans for a third in Puerto Rico (notwithstanding local political opposition to the project). When fully operational in a few years, the three stations should be able to monitor virtually all the planes in the air over the Caribbean and the northern half of South America, where most of the world's cocaine originates.
Using an altogether different kind of technology than conventional line-of-sight microwave radar, the system here works by bouncing signals off the ionosphere, the outer region of the atmosphere that begins about 30 miles above Earth. The greatest advantage of such a "look-down" approach is to eliminate hiding places for drug-ferrying planes, officials say.
Traffickers have been able to elude microwave radar by flying low or behind hills or by maneuvering between closely spaced islands. Such actions do not escape detection under the new system.
But relying on the unstable ionosphere as a kind of radar backboard presents problems. Most important, radar coverage can vary significantly with the time of day, time of year, sunspot activity and other conditions. The new tracking system requires constant adjustment by operators who scan continuously for the most advantageous sections of the ionosphere and the clearest radio frequencies.
"A major sunspot storm and we'll have difficulty tracking," said Petty Officer Jon Seward, among the most experienced operators here. "Sometimes a plane we're following will fly into a black hole in our coverage, and we'll try everything we can but won't be able to find it again."
The Navy originally planned to build 12 such radar facilities to keep its battleships apprised of the location of Soviet aircraft. The system was designed to be mobile, hence its name, Relocatable Over-the-Horizon Radar, or ROTHR. But moving one of these installations is no easy matter. Its hundreds of antennae and miles of wiring require months to unpack and assemble.
The new use was conceived several years ago. While testing a prototype in a cornfield about 40 miles south of Norfolk, operators noticed that large commercial aircraft were not the only things the radar was seeing crisscrossing the Caribbean.
"We looked south and saw lots of things flying around," Hillery said. "With the Cold War ending, the Pentagon said, 'Why don't we just leave it where it is and make it part of the counter-drug effort?' "
The system consists of two installations about 70 miles apart: a transmission site in New Kent, Va., consisting of 32 antennae laced with wires; and a receiver site here, 372 pairs of 19-foot tall aluminum poles arranged in two parallel rows stretching 1 1/2 miles. Operators sit in a windowless room at the receiver site staring at dozens of consoles showing color-coded dots, lines and complex patterns.
In general, the Clinton Administration has shifted emphasis from interdiction of cocaine toward assistance to South American countries where the narcotic is produced. But a variety of U.S. military assets remain engaged in identifying and tailing aircraft that travel the Caribbean.
U.S. drug enforcement authorities draw intelligence from microwave radar systems at ground-based stations throughout the Caribbean, Central America and the northern coast of South America. They also employ aerostats, or radar balloons, that float about 15,000 feet above the surface and are tethered across the southern United States and the Bahamas. Additionally, some P-3 patrol aircraft and old Navy intelligence-gathering ships have been refitted with special radar to assist in monitoring drug flights.
But ROTHR's 24-hour, all-weather capability, 2,000-mile range and wide coverage area add up to a marked advance over anything the military has used before.
"It's the most significant technological upgrade to fight drug operations," said Capt. Bruce Cavey, chief of counter-drug operations for the Atlantic Command.
Not everyone, however, is ready to declare salvaging ROTHR worth the cost. Officials at the Drug Enforcement Administration, for instance, are withholding final judgment until some of the system's limitations are corrected.
"I'm not completely as sanguine as the Defense Department is," said Doug Wankel, DEA's chief of operations. "But I'm comfortable with the direction they're going in."