According to Douglass, the FAA controllers questioned the aircraft. "Say what aircraft type," requested the controller.

"We are a classified type and can't reveal our true altitude," responded the pilot.

A few minutes later the same pilot requested permission to descend to 30,000 feet and a flight path to "Las Vegas with final destination somewhere in the Nellis Range."

"Trip home a bit slower, eh?" asked the FAA controller. To which the mystery aircraft did not respond.

The exchange monitored by Douglass is similar to earlier military radio transmissions monitored in the late 1990s. An unidentified aircraft code-named "Stove Pipe" once requested permission to cross the California coast en route to Nellis.

The aircraft refused to give its true altitude and speed. Californians, however, were quickly made aware of Stove Pipe because it generated an intense sonic boom as it passed over the coastline.

The aircraft set off several earthquake monitors as it passed overhead at several times the speed of sound. The space shuttle is known to trigger earthquake detectors when it passes over California for landing at Edwards Air Force Base.

Area 51

The U.S. Air Force's famed Area 51, or Groom Lake Facility, is located northwest of the Nellis, Nevada, test range. Area 51 has long been the source of much speculation about UFOs and advanced aircraft.

While many in the UFO enthusiast community suggest that these advanced vehicles are a result of extraterrestrial technology, the fact is that these new systems are of very earthly origin.

It is true that UFOs are the subject of a government conspiracy and cover-up. During the early 1960s the CIA launched a secret project called "Ox Cart," not to hide alien life forms but to hide a multimillion-dollar spy plane.

Ironically, for a project named after one of the slowest vehicles on Earth, Ox Cart involved one of the fastest creations in flight history, pioneered by aviation legend Kelly Johnson. The Ox Cart vehicle was to replace the high-flying U-2, also built by Lockheed and Kelly Johnson. The CIA sought a replacement for the U-2 after the Soviet Union shot down Francis Gary Powers over its territory.

In response to the CIA requirement, Kelly Johnson and his team at Lockheed's famed Skunk Works developed the SR-71 Blackbird. The SR-71 could fly higher than the U-2, over 100,000 feet, and traveled at over three times the speed of sound.

UFO Cover-up

As part of Ox Cart, the CIA also launched an effort to cover up the testing of its new high-flying reconnaissance plane. That effort included circulating stories of space aliens and flying saucers flying over the Western skies.

The CIA cover story for the SR-71 worked well enough for it to remain a secret until President Lyndon Johnson released details of the aircraft during a speech.

For nearly 30 years the SR-71 remained the fastest aircraft in active service, flying over global hot spots in Asia, Europe and the Middle East.

No Blackbird aircraft was ever lost to enemy action, but one was destroyed when it was launching an even faster vehicle. During the 1980s, several SR-71s were modified to carry a ramjet-powered unmanned vehicle designed to over-fly the most dangerous targets.

The single-engine ramjet pilotless craft were carried aloft on the back of the Blackbird and launched at over 100,000 feet and at speeds in excess of 2,000 miles an hour. One of these unmanned aircraft failed immediately after launch, colliding with the SR-71, instantly destroying both aircraft.

The SR-71 was eventually retired and may have been replaced by the mysterious Stove Pipe craft that set off the earthquake detectors in California. Because of its nature and recorded high flight speed, most sources indicate that Stove Pipe was actually a manned version of the Aurora space plane.

Aurora

Although never officially confirmed, Aurora was also developed by the Lockheed Skunk Works during the 1980s. The space plane was designed to operate either in a manned or unmanned mode. Its Cold War mission was to penetrate the anti-missile defenses surrounding Moscow at Mach 8+ speeds and deliver nuclear bombs onto multiple targets.

Aurora was described as a very large diamond-shaped vehicle and most likely powered by a hybrid jet-rocket engine technology. The craft could attain speeds in excess of 8,000 miles an hour and fly at altitudes of over 50 miles. Aurora was armed with over a dozen nuclear warheads.

The reason it was developed to be both manned and unmanned was because of its dual missions - peacetime reconnaissance and wartime nuclear strike vehicle. During times of peace, the Aurora carried manned crews to supervise surveillance.

During wartime, the very powerful Aurora accelerated and changed directions at speeds that would crush a human under the high G forces. Aurora's nuclear strike mission was intended to be without a pilot because a human simply would not survive the ride.

However, Aurora had two great drawbacks: its price tag and its mission. Aurora reportedly was retired from service in the late 1990s due to budget constraints. Each vehicle reportedly cost over $2 billion. The price of Aurora operations could not be justified when the Cold War ended.

Invisible Airplanes

What is the Skunk Works testing today? The unofficial reports indicate that the super-secret aircraft builders are hard at work on an invisible airplane.

Stealth was the watchword for the Lockheed F-117 Nighthawk. However, the stealthy strike fighter was visible to the naked eye, limiting its attack missions to the deep dark of night.

Today, advances in light panel technology are pushing the limits of invisible airplanes. The fact is that aircraft stand out against the bright sky as darker objects, but by using bright panels of light the aircraft virtually disappears against the blue sky.

Ironically, the concept is not new. In the 1940s, the U.S. Navy developed operation "Yahootie," the first practical attempt to create an invisible aircraft.

U.S. Navy bombers were considered too slow to visually spot a German U-boat cruising on the surface and attack in daylight. U-boat commanders often spotted the lumbering bombers and dived safely away before the planes could attack.

In response, a string of bright lights were arrayed on the wings and propeller hubs of the sub-hunter planes. The bomber crews adjusted the lights to match the natural background light behind the aircraft, masking their planes against the sky.

The principle is called isoluminosity, the perception that different objects displaying the same brightness seem indistinguishable from each other.

The principle worked very well until 1942, when the Navy introduced airborne radar, allowing bombers to spot and kill submarines beyond visual ranges. The Navy abandoned Yahootie in favor of radar.

An advanced version of Yahootie, a manned surveillance aircraft, reportedly uses a combination of lights, low-noise engines and radar-absorbing skin to render itself practically invisible in daylight. The aircraft not only is invisible to radar but also its skin is layered with an array of high-intensity light panels that broadcast the same output as the sky around it.