WASHINGTON (CNN) -- Where do fighter pilots traveling faster than the speed of sound go when they really need to "go"?

Pilots have struggled for years with the lack of toilet facilities in flight.

Until recently, the answer has been: into a bag.

But it's not a great solution. "Piddle packs" -- heavy-duty bags containing absorbent sponges -- have been blamed for at least two crashes over the years, and they're not always tidy.

A few years ago, after enduring years of complaints from pilots, the Air Force let it be known that it was looking for an answer.

A small medical equipment development company in Milton, Vermont answered the call.

"The DoD put out a list of projects they needed solutions for," said Mark Harvie, president of Omni Medical Solutions. "Bladder relief for pilots was one of the items on the list and we were looking for a new project," he said. Watch how apparatus makes it possible for pilots to drink up, fly high »

That project turned into the Advanced Mission Extender Device, known in military jargon as the AMXD.

After four years of testing by the Vermont Air National Guard and the Air Force and about $5 million in government and private funds, AMXD is spelling relief for pilots aloft.

Under the old system, pilots routinely avoid liquids before taking off to prevent the unmentionable. But dehydration can make them more susceptible to the G-forces typically seen in fighter aircraft, Harvie said.

When nature's call becomes too pressing to ignore, a pilot has to fly and unbuckle the harness at the same time -- while using both hands to maneuver around in a seat to which he or she is virtually molded.

The aerobatic maneuver is even harder for female pilots.

On long or cold-weather flights, the amount of gear and clothing made the maneuver nearly impossible, and pilots would sometimes have no choice but to relieve themselves in their flight suits.

In the AMXD, a cup for a man and a pad for a woman is strategically placed before the pilot dons a flight suit.

An instructional DVD tells pilots: "When the time comes to urinate, unzip the flight suit, remove the hose.... The control unit will pump the urine from the cup to the collection bag, where it will be chemically gelled." See how the system works »

Pilots are free to think about other business.

Harvie said the reviews have been positive from pilots of both genders. "One woman had the device taken away after testing and was quite unhappy about having to return to the old method," he said.

"The AMXD worked as advertised. I believe it's a much better system and needs to be fielded ASAP," says an unidentified pilot in a testimonial on the instructional DVD.

The Air Force recently bought its first 300 systems for U.S. pilots around the world at $2,000 each.

There's room for expansion. The air service has more than 4,200 fighter pilots who fly planes that have no bathrooms, planes like the F-16, F-15, A-10 and the most advanced fighter, the F-22.

The system has already seen action in combat zones: Female helicopter pilots from the Netherlands used the system in Afghanistan.

Harvie said it's too early to know whether the device will become standard issue, but it has attracted plenty of interest. "The Navy and Army are starting to look at the system for ground troops and carrier pilots, and looking at a version for private-sector uses," Harvie said.

Harvie said the Belgian Air Force has bought the system for its F-16 pilots.

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