SGT. 1ST CLASS KARL A. PETERSEN
Company A, 1st Battalion (Combat Aviation Brigade),
109th Infantry Regiment
Pennsylvania Army National Guard
Honesdale, Pennsylvania

In March 2006, I was the unit supply sergeant for an infantry company at Al Asad Airbase, Iraq. We were in the process of getting replacements for our two Marine platoons so they could rotate out. During this time, the incoming Marines received a lot of hands-on training — mostly weapon system familiarization of the systems for the assigned gun trucks. Most of the younger Marines were unfamiliar with these systems, so we tried to cover as much as possible. Sometimes, they would request extra training, which is what led to the following incident.

One morning, three of the new Marines asked if they could conduct hands-on training with the MK-19 grenade launcher. The platoon sergeant for the Marines allowed them to go into the convoy security teams’ building unsupervised, but instructed them to not touch any other items. In this room, there was a wall with a plywood shelving unit that was separated into 10 areas. This was where each gun truck downloaded its vehicle-specific equipment — such as weapons, ammunition and pyrotechnics — after a mission.

In the middle of the room, the Marines placed an MK-19 on a wooden box and began to conduct their training. As two of the Marines continued familiarizing themselves with the weapon, the other Marine went to inspect the other items on the shelves. He picked up an AT4 launcher and carried it over to the other Marines. Believing he was holding an expended round, the Marine went through the sequence of preparing the round for firing.

Standing just three feet from the other Marines, he cradled the AT4 in front of him at waist level and pointed the front of the weapon to his left and the back toward the shelving unit. He then took out the transport safety pin and pushed the cocking lever forward, unknowingly arming the launcher. When he held down the red safety release catch and pushed the trigger button, the AT4 fired inside the building.

I was in the next building with my company executive officer and unit armorer when we heard a thud. It sounded different from incoming fire, so we ran outside to see what happened. As I ran from the supply building, I saw white smoke billowing from the convoy security building and two dazed and confused Marines walking out the door. While several people ran to help, the Marines’ platoon sergeant came blazing by on his bicycle and hurried into the building. A few seconds later, he came out with the last Marine. After ensuring they were all OK, he went back inside the smoke-filled building to check for fire.

We followed him inside — fearing whatever had happened might ignite the other ammunition stored in the building. We found the AT4 launcher tube lying on the floor and figured it had been fired. Upon further inspection, we discovered the rocket had punched through a three-quarter-inch plywood wall that was 15 to 20 feet away, penetrating into the ammunition storage area that was on the other side. The round traveled between some crates of MK-19 rounds and other pyrotechnics before flying another eight to 10 feet and finally striking the exterior wall of the building. Fortunately, the rocket had not traveled far enough to arm (the manual states 33 feet as the minimum arming distance).

So how could this incident happen? Well, a few days earlier, the Marines went through an AT4 familiarization class that used a previously fired round we kept in our supply room. However, that round wasn’t marked as “INERT.” The Marine who fired the AT4 thought since the live round was identical to the one he saw in familiarization class, it, too, was inert and he could go through the arming steps like he did during training. Wrong!

These three Marines were lucky to be alive after this incident. However, one positive did come out of it. From that day on, all of our training devices were marked as INERT.


FYI

According to Field Manual 4-30.13, Appendix F, “Markings stenciled or stamped on munitions items include all information needed for complete identification. Components in which all explosive, incendiary, or toxic materials have been simulated by substitution of inert material are identified by impressed INERT markings. Components in which all explosive, incendiary, or toxic materials have been omitted are identified by stamped EMPTY markings.”