A total of 21 Titan I launches took place during 1961, with five failures. On 20 January 1961, Missile AJ-10 launched from LC-19 at CCAS. The flight ended in failure when an improper disconnect of a pad umbilical caused an electrical short in the second stage. The Titan performed well through the first stage burn, but after second stage separation, the fuel valve to the gas generator failed to open, preventing engine start. Missiles AJ-12 and AJ-15 in March were lost due to turbopump problems. Missile M-1's second stage lost thrust when the hydraulic pump failed. Missile SM-2 experienced early first stage shutdown; although the second stage burn was successful, it had to run to propellant depletion instead of a timed cutoff. The added stress of this operation apparently resulted in a failure of either the gas generator or turbopump, as the vernier solo phase ended prematurely. Missile M-6's second stage failed to start when an electrical relay malfunctioned and reset the ignition timer.