Iran's claims to have brought down one of the U.S. Air Force's stealthy unmanned RQ-170 Sentinel reconnaissance aircraft are highly dubious, analysts and Pentagon officials said.
However, the loss of contact with the pilotless jet cast doubts on the service's claim that it has a good handle on maintaining uninterrupted control of such aircraft.
On Dec. 4, Iran claimed to have shot down the stealthy Lockheed Martin-built aircraft. Later, government officials claimed that it had used an electronic or cyber attack to bring down the bat-winged drone and that the aircraft was recovered largely intact. The Iranians have not produced any evidence to back up those claims.
While acknowledging that an unmanned aircraft is missing, a spokesman for NATO's International Security Assistance Force (ISAF)-Afghanistan, U.S. Army Lt. Col. Jimmie Cummings, declined to say whether the aircraft in question was an RQ-170.
"Reconnaissance missions are, by their very nature, sensitive and as a result, I cannot get into that kind of detail," Cummings said. "It was on a mission over western Afghanistan when the operators lost control of it and we have no indication that it was shot down."
Pentagon spokesman U.S. Navy Capt. John Kirby added that there is no evidence to that suggests any kind of hostile activity was involved in bringing down the aircraft.
"We have no indication that the UAV we know is missing was brought down by any hostile activity," Kirby said.
Loren Thompson, an analyst at the Lexington Institute, Arlington, Va., said that the Iranians have no way to detect or engage the stealthy Sentinel.
"It would be almost impossible for Iran to shoot down an RQ-170 because it is stealthy; therefore, the Iranian air defenses can't see it," Thompson said. "Partly for the same reason, it is exceedingly unlikely that they used a cyber attack to bring down the aircraft."
Thompson said that from everything he has seen, the missing aircraft is a RQ-170. The Sentinel was designed to operate in contested airspace where ground-based air defense exists but where there is no severe airborne threat, such as swarms of patrolling fighters. In western Afghanistan, "it was operating in an area where it potentially could be susceptible to ground air defense attacks," Thompson said.
The Sentinel was developed in the early 2000s at Lockheed Martin's Skunk Works facility in California at the same time as the company's X-35 Joint Strike Fighter concept aircraft. The aircraft is operated from Creech Air Force Base and Tonopah Test Range in Nevada, according to the Air Force. The service acknowledged the jet's existence in 2010 after the Sentinel was photographed in Afghanistan.
Thompson said the most likely scenario with the crash is a malfunction with the aircraft. If the plane crashed due to a hardware or software glitch, Iran is likely sitting on practically useless wreckage with little intelligence value, he said.
"The RQ-170 has a RTB [Return to Base] feature," Thompson said. "In the event of a loss of the command link, the aircraft will automatically return to its point of origin and land itself."
The very fact that the aircraft was lost suggests a malfunction rather than a shoot-down, Thompson said.
The RQ-4 Global Hawk has a similar built-in automatic feature to find and land at a divert airfield if the link is lost. The lost link, airfield diversion issue and the inability of UAVs' to avoid other aircraft traffic are bones of contention between the Air Force and the Federal Aviation Administration.
As such, the incident highlights a fundamental problem that plagues current unmanned aircraft, which is that they have little in the way of active defenses and very little situational awareness, Thompson said.
"I think it's kind of inescapable that incidents like this raise doubts about operating unmanned air vehicles in civil airspace," he said.
However, attrition rates for unmanned aircraft are going down steadily, Thompson said. Eventually, the mishap rates will match those of manned aircraft, he said.
It has been an unlucky year for disclosed stealthy "black" programs. Earlier in the year, a heavily modified stealthy version of the U.S. Army's UH-70 Black Hawk crashed during the Joint Special Operations Command (JSOC) raid on Osama bin Laden's compound in Abbottabad, Pakistan.
This latest crash would be the second reported loss of a classified stealth aircraft in 2011. The Air Force would not confirm or deny if another RQ-170 had crashed earlier in the year.