As the only Jet capable base in South Vietnam during the opening stages of the US involvement in Vietnam, Da Nang soon became very congested and its facilities were soon being stretched to the maximum. To relieve some of the congested air space around Da Nang the USMC made the decision to establish a new base at Chu Lai, south of Da Nang. The Chu Lai base was to be in all effects a land-based aircraft carrier utilising a very short metal runway, with catapult launching and arrester hook landing procedures. Although Chu Lai was to allow an extra two extra squadrons to be deployed in addition to relieving some of the pressure on Da Nang its presence would not long go unnoticed by the communist guerrillas. Soon, as many as 3,000 Viet Cong had the Chu Lai base under siege, with the result that the base?s F4 Phantoms were soon being fully employed on strictly base security operations, rather than taking their part in the ?Rolling Thunder? operations against North Vietnam. Chu Lai Phantoms would also be involved in one of the most horrific air accidents during the Vietnam conflict. A F4 Phantom from USMC squadron ?VMFA-542? was in a mid-air head on collision with a KC-13OF whilst the latter was in the process of refuelling two other Phantoms from USMC squadron ?VMFA-314?. Both of the colliding aircraft were destroyed immediately with the loss of eight air crew. Of the two VMFA-314 aircraft that had been taking on fuel, one crashed into the sea after the crew had ejected, whilst the other made a forced landing at Chu Lai