Editor’s Note: We recall watching this “runaway blimp” event unfold on the news last fall, immediately knowing how much trouble it was going to cause and how many people would be screaming loudly about cost overruns, failed programs, Big Brother, and pretty much everything else under the sun. It’s almost laughable to think the whole thing could have been avoided by the installation of batteries.
The blimp that broke loose from an Army facility in Maryland last fall, wreaking havoc with its mile-long tether, flew uncontrolled for hours because someone neglected to put batteries in its automatic-deflation device, Pentagon investigators have found.
The pilotless, radar-carrying blimp was part of the troubled JLENS missile-defense system, which has failed to perform as promised while costing the government more than $2.7 billion since 1998.
The runaway blimp episode was caused by a cascade of events spanning 13 hours, according to people familiar with the investigation, an overview provided to congressional staff members and a summary released by a military spokeswoman.
The six-sentence summary of the investigation said that “design, human, and procedural issues all contributed” to the mishap. Pentagon officials declined to release a copy of the investigative report.
The blimp was one of two moored at the Army’s Aberdeen Proving Ground. On Oct. 28, it was floating at an altitude of about 5,200 feet when its tether tore apart.
Fighter jets were scrambled to track the blimp as it wafted over Maryland and Pennsylvania, and commercial air traffic had to be diverted. The blimp’s tether damaged power lines, knocking out electricity to 35,000 rural Pennsylvania residents. The tattered blimp finally came to rest in high trees in rural Moreland Township, Pa.
The incident made JLENS a target of widespread ridicule and provoked fresh questions about the program.
JLENS — short for Joint Land Attack Cruise Missile Defense Elevated Netted Sensor System — is designed to provide early warning of enemy cruise missiles, drones or other low-flying threats.
The blimps, also called aerostats, can float as high as 10,000 feet. At that altitude, their powerful radar can see 340 miles in any direction, farther than land- or sea-based radar, according to the system’s prime contractor, Raytheon Co.
The 7,000-pound aerostats are anchored to the ground by 1-inch-thick Kevlar tethers, which also hold wiring for electricity.
The two blimps at Aberdeen were participating in an “operational exercise” intended to test the system’s ability to defend the Washington, D.C., area. The exercise was suspended after the accident.
The sequence of events that caused the blimp to break away began when a pitot tube, a narrow 18-inch-long device intended to measure air pressure within the blimp, malfunctioned. Ground personnel failed to detect or address the problem, investigators found.
Ordinarily, fans within the blimp would activate in response to a change in atmospheric conditions, such as increased winds. But because the pilot tube failed, the fans did not operate — and air pressure within the blimp started to drop.
The blimp turned so that it was perpendicular to the prevailing wind, instead of the desired parallel position. Gusts that reached 69 mph bent its vertical tail fins out of their normal shape.
This made the blimp unstable in the air, putting greater pressure on the mooring tether than it was designed to withstand, according to the investigative documents.
Still, the blimp was equipped with an automated device that should have caused it to deflate promptly and return to ground within two miles. The device failed to activate, because batteries had not been installed as a backup power source, according to people familiar with the investigation.
The original article on Military.com can be viewed here.
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