The F-106 grew directly out of the F-102 Delta Dagger, America’s first delta-wing interceptor. The F-102 had been troubled — it could not go supersonic in level flight until its fuselage was reshaped to the “area rule” — and the Air Force wanted far more performance. The improved aircraft, originally the F-102B, gained a much more powerful J75 engine, a redesigned intake and fuselage, and the advanced MA-1 fire-control system. The changes were so sweeping that in 1956 it was redesignated the F-106A, a new type in all but ancestry. The result roughly doubled the Dagger’s capability and gave Air Defense Command the interceptor it had wanted all along — even if it arrived years later and in far smaller numbers than first planned.

SAGE was one of the largest computer projects of the early Cold War: a chain of blockhouses full of room-sized vacuum-tube computers that fused radar tracks into a single air picture and could hand an interception straight to a fighter. Aboard the F-106, the MA-1 fire-control system flew that interception. Ground controllers could uplink steering commands, and the aircraft could be guided to the firing solution automatically, the pilot largely monitoring rather than flying. It was a genuinely futuristic idea for the late 1950s — and a fragile one. The MA-1 was famously troublesome, receiving a long series of modifications over its service life. Read the automation claims of the era with some caution: the system worked, but never quite as seamlessly as the brochures suggested.

When it entered service the F-106 carried no gun — interceptor doctrine of the day held that missiles and a nuclear rocket had made cannon obsolete. Its internal bay held up to four AIM-4 Falcon guided missiles and a single AIR-2 Genie nuclear rocket. Combat over Vietnam soon exposed the limits of missile-only fighters, and from around 1972 many F-106s were retrofitted with an internal 20 mm M61 Vulcan cannon in a programme nicknamed the “Six Shooter,” which also added a clearer canopy. The Genie was only ever fired with a live warhead once, in the 1957 “John” test — and never in combat.

Firm cost figures for the F-106 are scarce and inconsistent, as is usual for a 1950s–60s military aircraft. Contemporary sources place the flyaway unit cost very roughly in the region of $4–5 million in early-1970s dollars, but this should be read as an order-of-magnitude estimate rather than a precise, audited price. No reliable public cost-per-flight-hour figure exists for the type. What is better documented is the aircraft’s reputation for reliability: the F-106 is often cited as having one of the lowest accident rates of any Century-series fighter, which helped keep it economical enough to serve for almost thirty years. Treat any exact dollar figure attached to the Six with healthy scepticism.