Because of the open LOX fill/drain valve, the Atlas's propellant system suffered a loss of fuel flow and pressure that caused the B-2 engine to operate at only 65% thrust.

Due to the imbalanced thrust, the Atlas lifted at a slanted angle, which also prevented one of the launcher hold-down arms from retracting properly.

The test was conducted with the Mercury astronauts in attendance in order to showcase the vehicle that would take them into orbit, but 64 seconds of flight ended in another explosion, prompting Gus Grissom to remark "Are we really going to get on top of one of those things?

"[3] This failure was traced to improper separation of the right launcher hold-down pin, which damaged the B-2 nacelle structure and caused helium pressurization gas to escape during ascent.

The hold-down pin had not retracted due to a sheared retaining bolt in the bell crank pulley system in the right launcher arm.

The flight of 7D resulted in improved maintenance procedures for the launcher equipment at CCAS and use of higher heat steel in the bell crank retaining bolts.

Although assorted minor failures and hardware bugs affected these flights, the overall success rate was a major improvement over the first half of the year.

An explosion ripped apart the thrust section, followed by structural failure of the propellant tanks, causing the Atlas to fall back onto LC-13 in an enormous fireball.

The Atlas went in for a repeat performance on April 8 when Missile 48D, launched from LC-11 and intended as the first closed-loop test of the AIG (All Inertial Guidance System), experienced combustion instability again, this time in the B-2 engine.

Since the propulsion system had not attained sufficient thrust, the launcher hold-down mechanism did not release the missile, which stayed in place and burned on the pad.

On 48D, the rough combustion did not occur in that engine and the lack of RCC cutoff was not a problem (B-1 thrust was terminated instead by the turbopump overspeed sensor).

It could not be determined with certainty if the lack of an exhaust duct had anything to do with the failures, and in any case, camera coverage did not offer any evidence in support of this theory.

Aside from re-installing the exhaust duct, camera coverage of the flame deflector pit at ignition would also be increased and greater efforts made to ensure that the booster engines were free of contaminants.

The flight was largely successful however an open circuit resulted in the programmer not receiving the VECO discrete from the guidance system at the intended T+300 seconds.

A backup command from the programmer performed VECO eight seconds later, consequently the RV landed 18 miles (28 km) further downrange than intended.

This resulted in depletion of control helium and decay in propulsion system performance, and so the Mark III Mod 1B reentry vehicle landed some 40 miles (64 km) short of its intended target point.

Missile 47D (September 12) lost sustainer thrust starting at T+220 seconds due to an apparent loss of helium control pressure to the gas generator.

81D (October 13) failed when the LOX quick disconnect pressure sensor malfunctioned due to the loss of a heat shield at liftoff.

The most notable flight in this stretch was Atlas 71D on October 13 which carried three mice and other experiments in a biological nose cone which successfully completed a 5,000-mile (8,000 km) lob downrange from LC-11 at the Cape.

This missile utilized a dry start method without any hold-down time at liftoff with no apparent ill effects and all airborne systems performed well aside from an unexplained decrease in B-1 and sustainer thrust a few seconds before BECO.

The sustainer shut down at T+181 seconds, likely due to a rupture from the excessive pressure level, and the missile fell an estimated 2,300 miles (3,700 km) short of its target.

Beginning at T+86 seconds, the V-2 vernier shut down followed by loss of B-1 engine gimbaling control, telemetry power failure, and booster thrust decay.

In March, a series of operational SAC tests were carried out with minimal telemetry to reduce weight and allow the missiles to fly for as long a range as possible—five Atlas D and F flights.

The missile began to tumble out of control shortly after liftoff and self-destructed at T+33 seconds after having performed a 320° loop, showering the area around the pad with flaming debris.

On April 23, 1964, Missile 263D launched from CCAS LC-12 as part of Project FIRE, a series of suborbital tests designed to verify Apollo command module ablative heat shield material.

The Atlas ICBM program concluded in early 1965, however refurbished missiles continued to be flown from VAFB for various orbital and suborbital mission for years afterward.

The first attempt using Atlas 172D miscarried when an incorrectly set sustainer PU valve caused fuel depletion and premature SECO.

The guidance system did not issue the separation command to the pods, which remained attached to the sustainer section as it reentered the atmosphere and burned up.

The second attempt, using Missile 68D on May 28, was an even bigger fiasco when a LOX leak during ascent resulted in a thrust section explosion two minutes into launch.

Mk 2 "heat sink" re-entry vehicle (RV) with a W49 thermonuclear weapon, combined weight 3,700 lb (1,680 kg) and yield of 1.44 megatons (Mt).