A highly promoted, high-flying unmanned reconnaissance aircraft may be getting too expensive to use in risky operations, a congressional committee says. The military says costly new enhancements are necessary to make the craft an effective target-hunter.

With new capabilities sought by the military, the cost of the Global Hawk spy plane, which made its combat debut in the Afghanistan conflict, is expected to reach $45 million to $50 million a copy, or as much as an F-16 fighter, Air Force officials say.

At issue are the competing visions for one of the Pentagon's latest technological wonders, the unmanned aerial vehicle, known as UAV.

With a proposed price tag of $10 million each, the Global Hawk was proposed years ago as a cheap substitute for manned reconnaissance planes like the U-2, whose pilots are at risk whenever they cross enemy territory to snap photographs or eavesdrop on communications.

The House Intelligence Committee, in a recent report on its classified intelligence budget, says the military has gotten away from that vision, however, opting to load up UAVs with expensive cameras and other sensors.

"You are no longer dealing with a cheap aircraft," said Rep. Michael Castle, R-Del., a member of the committee. "While not disposable (at $10 million), you could at least afford to lose them. Now you're dealing with something you don't want to risk losing."

But some in the military say the idea of expendable UAVs is out of date, and money spent to equip a Global Hawk with the best cameras and electronic eavesdropping technology will pay off in better intelligence on America's adversaries. Military officials say they fully expect the planes to go in harm's way and survive.

Senior Pentagon chiefs are standing by the plane. They say efforts are under way to reduce the cost.

"It's a tremendous platform," Pete Aldridge, an undersecretary of defense who is the Pentagon's chief weapons buyer, said in an interview with reporters. "To start all over again and design yourself a high-flyer like that -- it's going to cost just as much. It's just a matter of fixing it."

The plane's military value has increased to the point that the Pentagon wants to add defensive countermeasures to protect it from attack, which would add still more to its cost, officials said.

The Global Hawk is designed to fly well above any battlefield, at about 65,000 feet, safely out of range of many anti-aircraft weapons. It can loiter over a target area for more than a day to transmit reconnaissance pictures back to base. It carries no weapons.

Its endurance also allows it to photograph an area as large as Illinois in a single mission, said Air Force Lt. Col. Douglas Boone, who oversees the program.

Six have been built, and a seventh is to be completed this year. Three have crashed, including two that were used in the conflict in Afghanistan, leading some to question its reliability.

Although military officials say such crashes are to be expected in a new aircraft program, the Air Force has grounded the remaining three to seek the causes.

Beginning next year, the military wants to build at least 50 more, and the entire Global Hawk program is expected to cost $3.8 billion.

Another House criticism of the Global Hawk is it performs essentially the same mission as the U-2 -- taking many photographs from far away -- while the mission of the retired SR-71 Blackbird remains unfulfilled. The SR-71 performed what the military calls "penetrating reconnaissance," flying closer to a target for high-quality pictures.

The SR-71 could safely fly over enemy territory because it was so fast no missile or plane could catch it. A new plane, either with a pilot or without, probably would use stealth, rather than speed, to escape. Plans for a proposed UAV, the DarkStar, which would have performed this mission, were scrapped in 1999 after a prototype crashed.

Boone expects the Global Hawk to replace the U-2 in a decade or so. Any replacement for the SR-71 requires more money from Congress, he said.

The Air Force envisions Global Hawk as the largest of a family of three UAVs. Another is the Predator, a smaller, lower-flying plane that can transmit video. At least 70 have been built and 24 lost, including some in combat. The CIA has armed several Predators, which it has used to strike at suspected al-Qaida targets in Afghanistan.

These are more affordable than their big brother at about $4.5 million each.

A third plane, called the Predator B, also is in development. Boone describes the Predator B as a hunter-killer that would fly higher than the Predator and lower than the Global Hawk. It would be designed to carry short-range missiles or guided bombs.