Up, up, and very far away.

At least, that’s the U.S. military’s eventual goal for Phantom Eye — a ginormous, hydrogen-powered uber-drone. The vehicle, manufactured by Boeing and designed as a huge surveillance tool, performed its first test flight at NASA’s Dryden Flight Research Center last week, the company announced on Monday.

But Phantom Eye, which boasts a mammoth 150-foot wingspan, isn’t soaring to great heights just quite yet. During last week’s test, shown in the video above, the mega-drone reached an altitude of 4,080 feet and stayed airborne for a total of 28 minutes, reaching a cruising speed of 62 knots.

That’s a far cry from what the military wants the drone to eventually do. Phantom Eye is supposed to reach a maximum altitude of 65,000 feet and stay aloft for up to 96 hours — that is, four whole days — at speeds reaching 150 knots. That would make the flying spy the biggest and longest-loitering drone the United States has. (Don’t worry, it’s not armed.)

The Phantom Eye’s size means the drone can be loaded up with a whopping 450 lbs. of sensors and cameras — which will come in handy for toting the military’s forthcoming spy gear, like Gorgon Stare, designed to spy on “city-size” areas, or the Army’s ARGUS sensor, which collects the equivalent of 79.8 years of video footage each day. Combine that capacity with a lengthy loiter time, and you’ve got a high-flying spy system that can peek on entire cities for days at a time.

Phantom Eye’s flight debut was a small step forward for the ambitious drone, which Boeing first introduced in 2010. But the test wasn’t flawless — the giant spy machine sustained a broken landing gear upon touchdown. This isn’t the first time the mega-drone has encountered technical difficulty. Although Boeing initially planned to test-fly the Phantom Eye in 2011, that date was pushed back because of unspecified tech concerns.

Not to mention that, in 2010, the company aspired to an initial test flight of 8 hours. Last year, company officials told Danger Room that the Phantom Eye’s first flight had been scaled back to “maybe two to four hours.” Obviously, those goals are both far cries what Phantom Eye ended up accomplishing: 28 minutes in the air.

Of course, that’s what testing is for, and in any event, Phantom Eye is years away from actual military use. Still, it’s a little unclear what value a gigantic drone has, given that Congress is pushing the Air Force to deploy giant spy-blimps, which can lug even more spy gear while loitering for longer periods of time. But the blimps are technically complex and expensive, and the Air Force is getting cold feet about them.

Whether blimp-crazed politicians like it or not, Phantom Eye might turn out to be the military’s long-distance surveillance champ.

Video: Boeing