In September, plans to build an air base at Qui Nhon were suspended when the site conditions were found to be unsuitable.

[1] In late February 1966 Military Assistance Command, Vietnam decided to build a new jet-capable base at Phù Cát.

At this time the runway was a 3,000-foot (910 m) long dirt strip while the taxiways and parking areas were covered in Pierced steel planking (PSP).

[4][1]: 265 In September 1967 a detachment from the 4th Air Commando Squadron equipped with 4 AC-47 Spooky gunships began operating from the base.

[4] On 5 May 1968 the 174th Tactical Fighter Squadron (174th TFS), an Iowa Air National Guard unit equipped with F-100Cs deployed to Phù Cát AB.

[7] On 13 April 1969, Detachment 1 612th TFS left the base and was replaced by the 480th Tactical Fighter Squadron equipped with F-4D Phantom II combat aircraft which moved from Da Nang AB.

On 27 May the 416th TFS transferred to Tuy Hoa Air Base and the Commando Sabre Fast FACs were inactivated.

[2]: 452 On 1 February 1970 the base was hit by a People's Army of Vietnam (PAVN) rocket attack, killing one airman and wounding 15 others.

A Flight 17th Special Operations Squadron (17th SOS) equipped with AC-119G Shadows moving from Tuy Hoa Air Base replaced them at Phù Cát AB.

With more VC gathering for renewed attacks, the base commander contacted the 92nd Air Wing at Phan Rang AB for help.