T-0:00:02.7	Engine Start
The Russian-designed RD-180 main engine is ignited and undergoes checkout prior to launch.
T+0:00:01.1	Liftoff
The Atlas 5 vehicle, designated AV-012, lifts off and begins a vertical rise away from Complex 41 at Cape Canaveral Air Force Station, Florida.
T+0:03:39	Nose Cone Jettison
The payload fairing that protected the X-37B spacecraft during launch is separated once heating levels drop to predetermined limits.
T+0:03:39	Nose Cone Jettison
The payload fairing that protected the X-37B spacecraft during launch is separated once heating levels drop to predetermined limits.
T+0:03:44	Forward Load Reactor Jettison
The Forward Load Reactor deck that supported the payload fairing's structure to Centaur upper stage is released five seconds after the shroud's jettison.
T+0:04:24	Main Engine Cutoff
The first stage's RD-180 engine shuts down after completing its burn during the Atlas 5 launch.
T+0:04:30	Stage Separation
The Common Core Booster first stage of the Atlas 5 rocket separates from the Centaur upper stage. Over the next few seconds, the Centaur engine liquid hydrogen and liquid oxygen systems are readied for ignition.
T+0:04:40	Centaur Ignition 1
The Centaur RL10 engine ignites for its first burn of the mission.
T+0:17:18	Centaur Cutoff 1
The Centaur engine shuts down following its first burn. The launch will enter a news blackout following this milestone. Any subsequent Centaur burns, along with spacecraft separation, will occur in secret.

Data source: United Launch Alliance.