The main spy system on the U.S. Navy plane that's being held in China is called "Big Look" — and does it ever. 

 

From a "radome" under the front of the plane and from covered pods called "canoes" on the aircraft's top and underside, dozens of sensitive antennae pick up signals from radar, radio, cell phones, perhaps even e-mail. 

"It's got more antennae than a dog has fleas," John Pike, a private military analyst, said Tuesday. "The communist Chinese would love to pop those canoes off and get a look." 

The EP-3E Aires II plane made an emergency landing Sunday at a Chinese naval air base after colliding with a Chinese fighter jet. The Pentagon says its 24 crew members, still detained in China, sent a message that they began destroying the plane's intelligence-gathering equipment and information before landing. 

One of only a dozen such planes in operation, the aircraft uses a complex combination of receivers, antennae, computers, displays and recording devices to intercept radar and other communications signals up to 460 miles away. 

Put more simply, "The airplane is basically a really big flying tape recorder," said Pike, director of GlobalSecurity.org, a private defense policy organization. 

U.S. officials bristle at talk that the plane was spying on China. 

"Spies take part in espionage, and that's not at all what we're talking about here," said Pentagon spokesman Rear Adm. Craig Quigley. "This was overt, routine surveillance and reconnaissance." 

Spying or not, virtually anything transmitted through the air would be within reach. 

"You're sort of sensing the air," said Daniel Goure, a former Pentagon official now at the Lexington Institute, a think tank in Arlington, Va. 

With the plane's capabilities, the United States could pluck all sorts of information from the atmosphere. The specific characteristics of Chinese radar sites on land, at sea, even on planes would be of particular significance. 

Armed with that information, U.S. officials could develop ways to jam and neutralize the radars, said Jeffrey Richelson, a senior fellow at the private National Security Archive. 

Tracking communications among Chinese military leaders and units also could help U.S. officials determine locations of military forces and ships, their capabilities, how frequently they go on maneuvers, even how well-trained they are. 

Operating to the south of China as it was, the plane's focus most likely was Chinese naval operations, Goure said. 

In 1996, the six-plane squadron that includes the aircraft on the ground in China flew 1,319 sorties and picked up 2,911 signals of "tactical significance" from land, sea and planes in targeted countries and located 72 "nonfriendly" submarines, according to an annual history of the squadron obtained by Richelson. 

Were the Chinese to be able to analyze what the United States was learning from the plane, they could figure out "how leaky their system is," says Goure. 

"Then they could change what they do and make it much tougher for us to get the information next time around," he added. 

Paul Beaver of Jane's Information Group, publisher of Jane's Defense Weekly, said China also might gain insights into how the United States deals with electronic warfare, which could have implications for U.S. allies such as Japan and Taiwan that use American technology. 

"The Chinese could counter their systems as well," said Beaver. "We literally don't know the scope of what damage this could do if the Chinese in fact boarded the plane." 

Joseph Prueher, the U.S. ambassador to Beijing, said Tuesday on ABC, "We have every reason to think the Chinese have been all over the airplane." 

The plane's main antenna is known as "Big Look" and is housed in a flat, elliptical dome under the fuselage that is 12 feet in diameter and 3 feet deep. Dozens more antennae are found in upper and lower housings known as canoes. 

The plane's interior features rows of radar consoles running down both sides, with huge racks of computers and 19 work stations, where technicians search for, collect and interpret information. A folding ladder is stored inside the cabin for boarding and deplaning. The lavatory and galley are in the rear. 

Sophisticated as its intelligence-gathering techniques are, the four-engine turboprop is anything but nimble in flight — a "flying pig" is how one military commander described it Tuesday — it lumbers along at about 345 mph.