JOHN M. ABNEY
Safety Department, Marine Corps Installations East
Marine Corps Base Camp Lejeune, N.C.
Unit leaders face difficult decisions during combat conditions that sometimes force them to alter established orders and operating procedures. However, simulated combat scenarios, such as those that occur during training exercises, should not be an excuse to ignore technical manual instructions. Doing so could have deadly consequences, like what occurred in the incident described below.
The Marines departed their release point about 10 a.m. While en route to their first checkpoint, the convoy suffered a simulated improvised explosive device attack. In accordance with the rules of the exercise, the IED disabled a Medium Tactical Vehicle Replacement, so the Marines attached it to another MTVR in the convoy. The Marines from the disabled MTVR moved to the troop compartment of the towing vehicle, and the convoy continued on its route until they reached a 30-35 percent grade with a slight left turn.
As the vehicles descended the grade, the towed MTVR gained speed. The operator applied the brakes to the towing MTVR; however, the inter-vehicular airlines were not attached, which prevented him from slowing the towed vehicle. The mishap MTVR driver pumped the brakes in an effort to slow the vehicles’ descent. This caused a variation of momentum between the two vehicles, increasing the inability to maintain control.
The towing MTVR skidded slightly to the right toward an embankment as the towed vehicle continued on a straight path, which caused both to jackknife. The towing vehicle, having the most momentum, began a driver-side-to-passenger-side roll, eventually landing upside down on the embankment, killing one Marine and injuring four others in the troop compartment.
So how did this accident occur? Unfortunately, the Marines who attached the tow bar to the disabled vehicle failed to attach the MTVR inter-vehicular airlines and safety chains between the two, which was a common practice in Iraq. Some Marines in Iraq adopted a towing method where the tow bar was initially attached to the front towing shackles of MTVRs and HMMWVs and then fastened to the hood of the vehicle using cargo straps. This allowed for quick recovery procedures because the disabled vehicle only had to unfasten the cargo straps, connect to another vehicle’s pintle hook and continue on its route.
However, the MTVR tow bar technical manual requires that the inter-vehicular airlines and safety chains be used during all towing operations. Without the inter-vehicular airlines, the MTVR can’t brake evenly across all six axles of the towing and towed vehicles. Without this braking ability, momentum can cause the towed vehicle to speed past the towing vehicle and flip both. If the tow bar connection were to break, the safety chains are the final failsafe to ensure the coupled vehicles stay together. Unlike the 5-ton vehicle, the MTVR tow bar is a separate table of equipment item with its own SL-3. Unit leaders must ensure all SL-3 items for the tow bar are on hand for operations.
Furthermore, the operator committed two errors that contributed to this mishap. The post-mishap investigation indicated that the mishap vehicle was being operated in the Highway 0-2 central tire inflation system terrain setting rather than the required Cross-Country CTIS setting. The Cross-Country CTIS setting would have provided the operator with more traction and perhaps lessened the possibility of the vehicle losing control. Future convoy commanders must consider the type of terrain they will traverse and include CTIS settings in the convoy checklist.
The operator also made post-mishap statements that he focused his attention on the scenario-driven events happening in front of his vehicle rather than on the towed vehicle. This momentary loss of situational awareness led the operator to attempt to travel the decline at too great of a speed. Operators involved in towing operations need to understand the impact that a towed vehicle has on their maneuverability. It is recommended that all motor transport operators receive training on towing procedures with practical application that allows Marines to experience the difficulties involved in towing operations.
Towing presents a challenge for unit leaders and individual operators. Both need to be aware of the convoy speed, tow bar SL-3 and CTIS settings during all movements. Failure to follow the technical manual creates the possibility for mishaps such as this one.