FOUR DECADES AGO ON A MID-WINTER MORNING AT LARSON AIR FORCE BASE in Washington state, a cold war routine was being played out by Strategic Air Command B-52D bombers and crews of the 768th Bombardment Squadron (Heavy). Crews were at the end of five days on ground alert, living together in the “mole hole,” within sprinting distance of their aircraft. It was “changeover” morning, with fresh crews relieving those coming off alert.
My crew and one other 768th crew had a mission to fly before going home for a two-day break, then five days of flying before our next ground alert tour. I was a young first lieutenant who, at the moment, was strapped into the navigator’s seat aboard a B-52D, call sign Ranger 42. It was January 5, 1966, and a 27-hour workday was just getting started.
In 1961, SAC announced that nuclear-armed B-52s were conducting airborne alert missions. Code-named “Chrome Dome,” these flights were a part of SAC’s nuclear alert posture for seven years. B-52 units rotated on flying routes over the Arctic and Mediterranean. The idea was to reduce retaliatory response time in the event of a missile attack. To that end, several two-ship formations of armed B-52s were airborne around the clock within striking distance of the Soviet Union.
Most Larson crews flew an Arctic route, and though it was a complex, challenging, and exhausting mission, we considered it routine. On this morning, waiting for takeoff clearance with engines idling, Ranger 42 sat just off the runway and behind Ranger 41, the other 768th B-52 making up our flight of two. Each aircraft carried two 9,000-pound B53 nuclear bombs. Secured in each cockpit was a sealed metal box containing the top-secret “go codes,” charts, and target data necessary for the execution of a retaliatory nuclear strike.
One minute after Ranger 41 lifted off the runway, Ranger 42 was rolling. As the pilot slowly advanced the power on the eight J57 jet engines, he made his customary takeoff announcement: “Everybody grab a throttle and run forward.” A mile and a half later, we broke ground in the distinctive nose-low B-52 climbout attitude, bumping our way through a patch of the leader’s wake turbulence, then fell into two-mile trail formation.
Over Pennsylvania, the flight took up an east-northeast heading for our rendezvous with a pair of KC-135 tankers in the “Black Goat” refueling area off Newfoundland. Each bomber would take on about 12,500 gallons, enough to carry us over the pole and down to our next refueling, over central Alaska.
At 60 degrees north latitude, south of Cape Dyer and the Arctic Circle, it was time to “go into grid”—an air navigation technique used in polar regions where the unreliability of the magnetic compass and the acute convergence of geographic lines of longitude (meridians) close to the pole rule out steering by conventional methods.
On normal polar charts, the convergence of meridians close to the pole causes one degree of change in true course for each meridian passed. This change occurs more rapidly the closer the aircraft comes to the pole. The practical effect of this is that in order to fly a straight course, the aircraft would have to be placed in a constant turn—not good.
To solve the problem, grid navigation necessitated reorientation of the aircraft’s heading reference to a false north, what we referred to as “grid north,” by replacing the polar chart with a chart containing a square latitude and longitude grid. Because the meridians on the new grid chart were parallel to the Greenwich Meridian, the angle between grid north and true north could be calculated and a new geographic heading reference established.
Once this new heading reference was resolved, the aircraft’s primary compass was switched to a gyro-stabilized, free-running mode, then simply reset and maintained on the new grid heading.