1198th Operational Evaluation and Training Squadron The 1198th Operational Evaluation and Training Squadron was a unit at Norton Air Force Base , San Bernardino , California from 1965 to 1972 which conducted the initial testing of C - 130 Hercules transports modified for special operations under the project names of " Thin Slice " and " Heavy Chain " which led to the MC - 130 Combat Talon s , still a key component of Air Force Special Operations Command . Its initial commander was Lt . Col . Robert Marks . History . With the onset of operations interdicting supplies on the Ho Chi Minh Trail in Southeast Asia during the Vietnam War , the need for aircraft specially modified for night missions became apparent , amongst other tasks . In 1964 Lockheed had modified six C - 123B Providers for " unconventional warfare " under Project " Duck Hook " and then been tasked with adapting the C - 130E when the " Duck Hook " aircraft proved inadequate for the newly launched MACV - SOG . Two C - 130Es , " 64 - 0506 " and " - 0507 " , c / ns 3990 and 3991 , were transferred to " another agency " in December 1964 , generally assumed to be the Central Intelligence Agency , and were " sanitized " ( stripped of all identifying marks and plates to ensure deniability if the airframes were lost on discrete operations ) . Modifications were made by Lockheed Air Services at Ontario International Airport , Ontario , California , and the aircraft were operated by the 1198th OE & TS out of Area II on the northeast side of Norton AFB , thirty miles east of Ontario . In April 1967 , two On Mark Marksman , civilianized A - 26 Invader s , were transferred from Intermountain Aviation , an air service related the US Central Intelligence Agency , to Air America , another air service connected to the Agency . The official role of these aircraft as stated in the specifications provided to Air America from Intermountain in March 1967 was " Aerial resupply , [ and ] low - level penetration . " Both aircraft had been highly modified with a variety of navigation and other electronic equipment for this role . Between June and October 1967 , the first aircraft , re - registered from N900V to N46598 , conducted low - level night time supply drops to CIA related forces in Laos during the so - called " Secret War " . The program was discontinued because the aircraft was too fast for accurate drops even with the special onboard equipment , and looked too much like a type of strike aircraft known to operate in the theatre . This was cited as often causing forces on the ground to be wary of turning on their marking lamps . The aircraft was damaged on takeoff at Takhli Royal Thai Air Force Base after being transferred to Overseas Aeromarine , Inc . The second aircraft , officially re - registered from N800V to N67623 , was intended for the same role but never used . Both aircraft were initially painted in Insignia Blue , plus white trim areas outlined with black pinstripe that led the type to be nicknamed " the Blue Goose . " In the end , both aircraft were handed over to the 1198th OETS at Norton Air Force Base , San Bernardino , California , a unit known for alleged participation in agent dropping and other clandestine missions in Southeast Asia ( Project Heavy Chain ) . The Squadron evaluated the two Marksman , but apparently found no use for them and scrapped both aircraft , which suffered from a chronic Invader issue of nose gear failure .