The Utility Tactial Transport Helicopter Company (UTTHCO) was deployed to South Vietnam in 1962 
as a means of testing various new theories of airmobile warfare under development by the United States military.  
It operated in direct support of ARVN operations in various areas of the country, 
notably participating in the infamous ARVN attack on Ap Bac.  
UTTHCO units is included in the ARVN rather than the US OOB because it operated solely 
in South Vietnam before being redesignated and reincorporated into the US Army.  
It is better suited to the ARVN OOB because of this.