PLGR explosion injures one, prompts safety measures

An Army Global Positioning System (GPS) receiver manufactured by the Collins division of Rockwell International Corp. exploded during an exercise at Fort Irwin Calif. last month injuring one soldier who required hospitalization.

The blast caused the tri-service GPS Joint Program Office (JPO) to recommend safety measures that could affect the operation of thousands of military-standard GPS receivers until the cause of the explosion is determined through testing and corrective actions are taken.

The incident Federal Computer Week learned resulted from a "violent venting" of the battery in a Rockwell Collins Precision Lightweight GPS Receiver (PLGR) in a vehicle carrying Maj. Gen. Paul Kerns commander of the Army 4th Infantry Division Fort Hood Texas. The PLGR which was being used in a mount that draws power from the vehicle's electrical system exploded injuring the general's driver.

The PLGR is the standard tri-service handheld GPS receiver. The three services have fielded a total of 55 000 units with the Army purchasing the bulk. A spokesman for the Army Communications-Electronics Command (Cecom) which manages the PLGR program confirmed the explosion. He said that Cecom is conducting tests to determine the cause. The spokesman also confirmed the injury but said the soldier had totally recovered. Rockwell Collins declined to discuss the explosion referring all calls to the Army.

Military e-mails indicate that Cecom will try to narrow down the cause of the explosion focusing first on the possibility of such an incident occurring with the receiver operating in a stand-alone mode then in a vehicle mount configuration.

Until the cause of the explosion can be confirmed the tri-service JPO has recommended that all batteries be removed from the PLGRs when they are connected to vehicular power. But the message warned such a move has "operational considerations. It will cause faster use of the memory battery causing the memory battery to fall below the adequate power level."

This one e-mail added will result in "loss of the Comsec [communications security key]." The security key allows military receivers to tap into an extremely accurate signal from GPS satellites which deliver a location in the 5- to 10-meter range compared with the 100-meter accuracy available to nonmilitary receivers. The security key also enables military receivers to tap into anti-spoofing signals contained in the military code allowing those receivers to distinguish between a real GPS signal and one transmitted by an enemy attempting to broadcast false information on the GPS frequencies.

The loss of the COMSEC key the message said "in turn [could] cause a loss of almanac and user waypoint data." Because of these problems the JPO suggested that "users should assess their operational impact and risk before removing the BA-5800 [battery]."

The Defense Department considers GPS as one of the key technologies of modern warfare because it allows units to locate themselves with pinpoint accuracy. PLGRs will serve as a key technology in next year's Force XXI digitized battlefield demonstration.