"We've gradually been sending them out," he said about the $45 million planes that, because of their still-classified nature, were spared going to the so-called "boneyard" at Davis-Monthan Air Force Base where rows and rows of outdated military aircraft bake in the Sonoran Desert sun near Tucson, Ariz.

"They're basically unbolting the wings. They'll be in 'recallable' condition," he said, referring to the status Congress deemed for the fate of the F-117As.

Since 2006, when Air Force officials announced the fleet of 52 Nighthawks probably faced an early retirement because of expensive maintenance costs and the arrival of the superior F-22A Raptor stealth attack jet, they decided instead to return all but a few to secure hangars at Tonopah rather than send them to Arizona.

"They're not going to Davis-Monthan," Ponder said. "There was some speculation they would go there, but until they completely declassify everything, they're going to Tonopah."

Part of the reason is because some of the F-117A exhaust system is classified, he said.

The F-117A stealth jet with its secret, black coating and oblique, batlike shape revolutionized air warfare because it could evade radar detection and drop precision-guided bombs at night.

Much of the aircraft was made from off-the-shelf parts. The landing gear came from F-15 Eagles, engines from F-18 Hornets and controls from F-16 Falcons.

The Lockheed F-117A was developed under a tightly guarded program in the 1970s and early 1980s, with much of its testing and development taking place at the classified Area 51 installation along the dry Groom Lake bed, 90 miles north of Las Vegas, sources who worked there have said.

The F-117 fighter-attack jet made its first flight on June 18, 1981, and the first war-fighting Nighthawks were based at the Tonopah Test Range.

After the stealth program was declassified in November 1988, the first warplanes were deployed in combat over Panama during Operation Just Cause in December 1989 to help spur the surrender of military dictator Manuel Noriega.

Between 1989 and 1992, the war-fighting Nighthawks were assigned first to the 4450th Tactical Group and later the 37th Tactical Fighter Wing.

In the Persian Gulf War in 1991, 36 F-117As bolstered the allied effort against Iraq by bombing targets in Baghdad.

The original wing at Tonopah on Nellis Air Force Range was relocated to Holloman after the Persian Gulf War, with the first plane arriving at Holloman in May 1992.

Fifty-nine production models were made, with the last rolling off the line at Lockheed's Palmdale, Calif., plant on July 12, 1990. Seven were destroyed in crashes, including one lost in combat over Yugoslavia on March 27, 1999, in the Kosovo war effort.

Two F-117As spearheaded the U.S.-led invasion of Iraq during Operation Iraqi Freedom in March 2003. They flew unescorted over Baghdad and dropped bombs on Dora Farms, where intelligence sources thought Iraqi leader Saddam Hussein was hiding.

The F-117A made its public debut on April 21, 1990, when it was put out for a display that drew 350 media representatives from around the world and tens of thousands of viewers from the Las Vegas Valley.

Fittingly, the last four Nighthawks will depart Holloman for their return to seclusion at the Tonopah Test Range on April 21, exactly 18 years after the Air Force trotted them out for the world to see. Ponder said the four will fly first to Palmdale for "a short jaunt there" before heading to the Tonopah Test Range airfield.

In March, a trio of F-117s will fly to Wright-Patterson Air Force Base, Ohio, and then fly over the Pentagon and the Air Force Memorial.

The first 10 were retired in December 2006, Ponder said.

One aircraft will be left for static display at Holloman, but unlike one mounted for display at Nellis Air Force Base, "ours won't be on a stick. We'll have landing gear and all that," he said.

One F-117A will be destined for the Smithsonian National Air and Space Museum.

Contact reporter Keith Rogers at krogers@reviewjournal.com or (702) 383-0308.