Beckwith always blamed Carter for his interference in the details of the operation, such as not allowing him to use Army helicopter pilots.
And Beckwith was a moron who didnt know squat about aircraft. The pilots were almost all Marine with one Navy and one Air Force who qualified the series of tests.
All the Army pilots who tried out for the mission failed. Besides, the Army had no such long range aircraft in their inventory that could have been moved in secret like the RH-53 could have.