Aging Navy planes are outmaneuvering maritime drones in catching cocaine hustlers traveling by sea, according to Homeland Security Department statistics.

The department’s more than 40-year old fleet of 14 P-3 turboprop aircraft, obtained from the military, flies in all weather conditions from as far south as the Galapagos Islands all the way north to the waters surrounding Central America. Two Guardian drones, the maritime version of DHS’ land-based Predator drones, cover roughly the same seas, just a little less south, and can outlast the P-3s in the sky by about 10 hours.

Still, in fiscal 2011, the aged jets helped intercept $11.1 billion worth of cocaine weighing the equivalent of 76 Volkswagen Beetles, a DHS Customs and Border Protection spokesperson said. But the high-tech drones did not contribute to any sea-based seizures during that time.

One likely reason for the drones’ relatively poor performance: The department’s inspector general reports that the Guardians and Predators sit idle 63 percent of the time that they are supposed to be flying, partly because they can’t be dispatched in inclement conditions. Also, a lack of staffing and equipment, Federal Aviation Administration restrictions and other constraints have grounded operations.

The accomplishments of the P-3s compared to the drones come at a time when privacy advocates, lawmakers and many Americans are skittish about expanded use of robotic eyes in the skies. By contrast, CBP has not received any privacy complaints about the P-3s, according to agency officials.

Another factor that may be inhibiting the unmanned aircraft is the Joint Interagency Task Force South, a command uniting DHS and the intelligence community as well as the Defense and Justice departments, is not yet comfortable having the Guardian help in the fight against drugs.

“We’re not using that specifically in that [task force] effort, again, because it’s a very focused capability,” Gen. Douglas Fraser, commander of the U.S. Southern Command, said in March, according to a transcript of a discussion Fraser had with the Defense Writers Group. Controllers must “have it at the right place at the right time to support efforts.”

Fraser also expressed doubts about deploying military unmanned aerial vehicles returning from the Middle East.

“I’m not sure just because it’s a UAV that it will solve and fit on our problem set, so we’re still working our way through that issue, because as we look at how we then transmit that information, how it gets to our partner military law enforcement partners and how they then use that, there’s a lot bigger architecture that needs to be addressed than just having a UAV,” he said.

The Guardians’ lack of demonstrated success in interdicting drugs raises questions about why DHS is paying for counternarcotics drone technology.

CBP officials describe the P-3s as more efficient than the Guardians, but less persistent. Drones can soar for up to 20 hours, whereas P-3s can stay in the air for a maximum of 12 hours.

In 2011, the manned planes caught an average of $30 million worth of cocaine per day, the CBP spokesperson said. During the last five years, they have detected more than 853,000 pounds of cocaine. Officials declined to comment on the success rate of the Guardians, or specify the amount of cocaine they have helped intercept since starting to launch in 2009.

It is difficult to weigh the costs of the two aircraft against each other. P-3s are priced at $36 million apiece, according to the Navy, while Homeland Security reports each of its drones cost $18 million. After a trial in fiscal 2004, Congress disbursed $240.6 million to establish a drone program at DHS. The department has since gradually acquired 10 of the aircraft and spent an additional $55.3 million on operations and maintenance from fiscal 2006 through fiscal 2011, according to the recent IG report.

CBP declined to specify the cost of operations and maintenance for each Guardian and P-3, but said personnel expenses for the two cannot be compared. While more people are required to pilot the manned aircraft, both vehicles rely on the same analysts to process and distribute video surveillance collected. The P-3s usually require a pilot, co-pilot, flight engineer and four detection enforcement officers. The unmanned aircraft systems need only a pilot, sensor operator and radar worker.

It should be stressed that drones have at times been effective at catching drug smugglers. Predator missions conducted over land areas have yielded victories. CBP officials reported that during fiscal 2011 drones contributed to the seizure of more than 7,600 pounds of narcotics. The Predators, not the Guardians, assisted with those seizures, the CBP spokesperson said.

Former DHS Counternarcotics Enforcement Director Grayling Williams sees benefits to retaining both the P-3s and the Guardians. He noted P-3s, like drones, don’t always detect narcotics on their own. Sometimes Joint Interagency Task Force South directs P-3 pilots to prime spots for catching images of criminals in the act, he said.

“Through JIATF-S they do get tips,” said Williams, who retired in December 2011. “Depending on what’s going on, they may get vectored into a certain area . . . It’s a combination of getting tips but also doing a good job at surveillance.”

Having both assets on hand allows the government to adapt tactics when criminals change their methods, he said. Traffickers constantly are altering their means of transportation to outwit U.S. authorities in the sea and the sky. Semisubmersibles, or partially underwater ships, can travel great distances without surfacing to refuel. Go-fast speedboats, the most popular vessels among smugglers in the Caribbean, often are used at night to evade detection.

On the P-3s, “these men and women are out there every day and they take their job extremely serious,” said Williams, now chief of internal affairs for the Baltimore Police Department.

He added that the manned turboprops and or unmanned aerial vehicle systems, or UASes, are equally quick to alert vessels from the Coast Guard of suspicious activity. “Whether it’s me sitting back here in an air conditioned room looking at a camera screen from the UAS” or in the air on the P-3, “they can just put a call out to the Coast Guard,” Williams said.

Regarding the alleged privacy drawbacks, he said people who are not breaking the law have nothing to fear from drone pilots. “You are talking about federal law enforcement. You are not talking about the U.S. military. You are not talking about a war zone,” he said.

The CBP spokesperson said there are clear aerial surveillance protocols to ensure that privacy and civil rights are protected. In addition, CBP treats video from manned and unmanned aircraft the same, using established evidence handling policies. Guardians carry the same sensor and radar technologies as P-3s. And the drone’s onboard camera is very similar to the ones attached to many of CBP’s other aircraft.