Courtesy of George Devorshak, Colonel, USAF (Ret)
In the Fall, 1966, 7th Air Force tasked the 12th TFW to take over the MIG CAP missions over the Gulf of Tonkin being flown by the 479th TFW F-104 force at Udorn Royal Thai Air Base. A representative of the 12th TFW went to Udorn to get briefings on the mission in order to complete an orderly and efficient transition of this mission to the 12th TFW.
The mission was to establish a Combat Air Patrol to counter potential MIG attacks against two support aircraft code-named Silver Dawn and BigEye flying over the Gulf of Tonkin off the coast of Haiphong Harbor. The CAP track consisted of the northernmost point being no closer than 15 nautical miles from Hainan Island, with the closest leg of the CAP orbit to North Vietnam being just outside of SA-2 Surface-to-Air missile range, and generally centered abeam Haiphong. These, of course, were Route Package 6 missions.
Phantoms were selected for this mission because of their endurance, long-looking radar, and their superior air-to-air armament load which consisted of 4 AIM-7D Sparrow missiles, 4 AIM-9B Sidewinder missiles, and a full centerline GAU-16 20 millimeter cannon pod with 1200 rounds of high-explosive, armor-piercing, and tracer ammunition.
The missions were commonly referred to as "Silver Dawn." Each mission, consisting of a flight of 4 aircraft, was normally scheduled to be about 4 and one-half hours in duration, including transit time to and from Cam Ranh Bay. Two aircraft were to be on CAP station at all times, and the other two would cycle to and from KC-135 tankers flying over the Gulf of Tonkin just off the coast of DaNang, well south of the MIG CAP track. Each flight of 4 aircraft was to be relieved by another flight of 4 aircraft during the day, with a total of 12 F-4's from the 12th TFW committed every day to this mission. As often happens in combat, however, contingencies occur, and sometimes replacements did not show up because higher-headquarters diverted the replacements to another mission or because aircraft broke. Not infrequently, a flight had to stay on this MIG CAP for two "shifts" and occasionally three "shifts," resulting in over 12-hour missions. The Silver Dawn and BigEye missions were considered important enough by higher-headquarters so that if there was no CAP available, other missions over North Viet Nam were cancelled. Aircrews tasked for these MIG CAP missions quickly learned that it was prudent to carry along food and drink, and "piddle packs."
A short time after the 12th TFW started flying the Silver Dawn missions, the 12th TFW also started getting tasked to fly MIG CAP and Escort missions for pairs of EB-66's that were flying Electronic Warfare missions in Route Package 6. Almost all of these missions were north of Hanoi, just below the Chinese buffer zone that was established about 15 nautical miles south of the China border. The EB-66's seemed to be a priority target for the North Vietnamese at that time because very often 2 MIG-21's would attack the flight at very high airspeed, 1 pass, then head into China with impunity because of the buffer zone that they must have known existed.
At that time, the entire air structure was divided into 10 nautical mile grids, with double lettering designations. For example, the grid that encompassed Hanoi and Phuc Yen airfield was AG (Alpha Golf). The Mig's were parcelled in three categories; Blue was Mig-21, Red was Mig-19, and White was Mig-17. So if a threat came up, we would hear a call over the radio such as "BLUE, ALPHA GOLF." This kind of radio call prompted the MIG CAP fighters to "point" in that direction from wherever they were to acquire and counter the threat, and it also prompted the flight of 2 Phantoms at the KC-135 tankers awaiting their turn at CAP to immediately return to the CAP area for support as necessary.