TUCSON, Ariz. -- An aerial drone, zooming somewhere out of sight high above the cooling scrubland, first spotted the group of nearly two dozen migrants.
Snaking through the Sonoran Desert on a warm, moonless night last month, the would-be immigrants traversed the rugged foothills southwest of Tucson, a few miles north of the U.S.-Mexico border.
It had been a relatively quiet shift in that area for U.S. Border Patrol agents, who paused to chat in their passing green-and-white SUVs as dusk crept closer. But just after 10 p.m. agents perked up, their radios crackling with activity.
A fixed-wing Cessna took over from the Predator B unmanned plane and from overhead the pilot helped direct agents toward the migrants, who wove around ocotillo and brush.
A helicopter swooped in, its spotlight beaming over the hillside and rotors slicing the desert solitude as agents dropped down a ridge to chase the scattering group.
All told, a dozen men and women in olive uniforms converged. They rounded up eight of the migrants, walked them toward their gathered trucks and lined them up in a shallow drainage ditch along a washboard dirt road. A few of the migrants asked about the "camera in the sky" that had caught them.
A pilotless aircraft may have awed the failed migrants, but such success stories about U.S. Customs and Border Protection's quarter-billion-dollar drone program come in short supply, according to a Homeland Security Department inspector general's report released Monday.
Grounded by wind and bad weather, costly maintenance and poor planning, the underachieving aircraft have flown only a fraction of the agency's desired flight time from four bases in Arizona, Texas, Florida and North Dakota, the inspector general found.
In Arizona, where the agency keeps four drones, agents seemed pleasantly surprised that an unmanned craft had aided their efforts, though they had apprehended fewer than half of the detected migrants.
In its audit, however, the inspector general recommended that the agency stop buying the drones, manufactured by Poway-based General Atomics Aeronautical Systems, until officials can properly plan how to get the most out of the unmanned planes and budget for the program, which includes having enough equipment to perform their mission.
"CBP has not adequately planned to fund unmanned aircraft-related equipment," such as ground control stations, ground support equipment, cameras and navigation systems, the inspector general report says. "As a result of CBP's insufficient funding approach, future UAS [unmanned aerial systems] missions may have to be curtailed."
Customs and Border Protection officials said they concurred with the inspector general's recommendations and were committed to continuing to improve the drone program. In its written response to the inspector general's report, the agency said it had no plans to add more drones beyond the 10 already in operation or on order "unless directed by a higher authority."
The agency's previously stated goal was to expand to 24 drones, which cost about $18.5 million for the Predator B and $20.5 million for the maritime version, known as the Guardian, to operate. Those costs include maintenance, surveillance technology and ground equipment.
In the past year the agency has added two unmanned aircraft to its underutilized fleet and expects to receive its 10th system by September. The agency can still purchase up to 24 drones, but authorization is based on the availability of funding.
Officials this year also hope to secure permission from the Federal Aviation Administration to extend drone coverage just east of the San Diego metropolitan area, the last major section of the Southwest border to be patrolled by the aircraft.
Drones now patrol about 1,200 miles along the Southwest border from the Gulf of Mexico to just east of El Centro in southeastern California and can stay aloft for 20 hours.
Championed by Congress, derided by critics
The report echoes what critics -- including some Border Patrol agents -- have long said about the expensive, remotely controlled Predator B fleet.
They point to what they view as the program's meager returns since it began since 2006, as the drones have assisted in the seizure of nearly 50,000 pounds of drugs and the detention of about 7,500 people.
By comparison, decades-old P-3 Orion propeller planes, which once hunted submarines for the Navy, in the past five years have aided in the seizure or disruption of 863,000 pounds of drugs -- including 148,000 pounds of cocaine last year alone. Agency officials have described the plane as an "unsung hero."
"It is my sense that Congress has consistently overlooked (dare I say, 'ignored') not only the operational effectiveness, but also the cost effectiveness of the Predator [unmanned aerial vehicle] as a border surveillance tool," David Olive, a Washington-based homeland security consultant, wrote last year for the Security Debrief blog.
Customs and Border Protection officials have defended the drones, saying they are also used to assist in disaster and emergency relief, such as flooding, and other reconnaissance. The Office of Air and Marine also has flown missions for other agencies, including the FBI, FEMA, the Defense Department, Texas Rangers and the U.S. Forest Service.
Critics like Olive have said that the drones haven't met expectations in other situations, such as the Deepwater Horizon disaster in 2010, when the on-scene commander waved off the drones after a couple of weeks because they weren't helpful.
The inspector general also found that the agency does not have agreements to get reimbursed for missions flown for other agencies nor does it have a formal process to handle requests from outside agencies or ways to prioritize such missions.
In 2011, the agency's Office of Air and Marine flew its drones more than ever -- roughly 4,500 hours and 75 percent above any other fiscal year.
But that flight time amounts to a quarter of the agency's goal. The systems cost about $3,200 per hour to fly, for a total of about $14.5 million last year alone.
The result: Unmanned aircraft last year helped to find about 7,600 pounds of marijuana and apprehend 75 people suspected of engaging in illicit activities, according to the agency.
Overall, the U.S. Border Patrol, which is also part of Customs and Border Protection, in 2011 seized more than 2.5 million pounds of marijuana and apprehended 340,252 people, agency records show.
Rep. Henry Cuellar, D-Texas, who has championed drones as the Democratic co-chairman of the Congressional Unmanned Systems Caucus, said that Customs and Border Protection has to go back to the basics and come up with a sound strategic plan for its drones.
"The first thing any agency should have is a strategic plan. I assumed they had a plan," said Cuellar. "We have to know where we are going before we start buying any more of the assets."
Yet, the program -- and drones in general -- continue to receive wide-ranging support from lawmakers. The unmanned systems caucus, which promotes "the overwhelming value" of drones and "the urgent need to rapidly develop and deploy" more of them, has nearly 60 members, including 11 California representatives and the Republican chair of the House Intelligence Committee.
The House Homeland Security Appropriations subcommittee recently pushed for an increase above the Homeland Security Department's request for $18.6 million to buy, deploy and operate sensors and other equipment used on its existing drones.
The Senate Armed Services Committee, meanwhile, has called for the broader use of unmanned aircraft in the country's national airspace as large numbers of drones used in Afghanistan and other operations may return to the United States as those battles wind down.
"Without the ability to operate freely and routinely in the [National Airspace System], UAS (unmanned aerial system) development and training -- and ultimately operational capabilities -- will be severely impacted," according to a recent committee report.
Technologically advanced -- weather permitting
Touted for their technological advances and airborne omniscience, the drones require on average an hour of maintenance for every hour in the air, the report states.
Between 2006 and 2011, the agency spent $55.3 million to operate and maintain the drones. Congress has only appropriated $12.6 million for such costs, which include training, satellite links, facility rental and contractor support, since the agency's drone program began, according to the report.
Customs and Border Protection figures show that Congress has appropriated $240.6 million to establish, operate and maintain the unmanned aircraft program, which consists of 10 systems, and spent about $224 million.
Yet, winds often keep the drones on the ground, as it happened in late May when a reporter visited the Corpus Christi Naval Air Station, where two such aircraft are based. Cuellar said in his two visits to the base pilots could not launch or retrieve crafts because of weather conditions. The Predator B design allows it to take off and land in winds up to 30 miles per hour.
Cuellar said he plans to address the issue next week during a House Homeland Security Subcommittee meeting. He said he has pushed the agency to station the drones at other places that provide more consistent flight conditions. But officials have been "stubborn" about keeping the drones on military bases for security reasons.
"That's almost insulting to say there's no other place along the Texas border that can provide security for [unmanned aircraft]," he said.
G.W. Schulz of the Center for Investigative Reporting contributed to this report.