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Soyuz countdown timeline
Posted: April 1, 2014

T-04:20:00 Russian State Commission Meets
The Russian State Commission meets to authorize fueling of the Soyuz rocket.
T-04:00:00 Fueling Begins
Loading of kerosene and liquid oxygen propellants begins for the Soyuz rocket's three lower stages.
T-01:45:00 Fueling Complete
The rocket is fully fueled for launch.
T-01:00:00 Gantry Retracts
The 170-foot-tall mobile service gantry moves to the launch position on rails, revealing the Soyuz rocket for launch.
T-00:10:00 Sentinel 1A on Internal Power
The Sentinel 1A spacecraft is switched to internal battery power for launch.
T-00:06:10 Key on Start
The launch key is put in place in the control center to begin the Soyuz synchronized countdown sequence.
T-00:05:00 Fregat on Internal Power
The Fregat-M upper stage is tranferred to internal battery power.
T-00:02:25 Upper Umbilical Retracts
The umbilical arm reaching the upper portion of the Soyuz rocket retracts. This event also ends the stream of spacecraft telemetry to the Sentinel 1A control center in Germany.
T-00:00:40 Soyuz on Internal Power
The Soyuz rocket transitions to internal power.
T-00:00:20 Lower Umbilical Retracts
The umbilical arm servicing the lower portion of the Soyuz rocket retracts.
T-00:00:17 Ignition
The ignition sequence begins for the Soyuz rocket's core stage and four strap-on boosters.
T-00:00:03 Full Thrust
The RD-107A and RD-108A engines reach their full power level, totaling more than 900,000 pounds of thrust.
T-00:00:00 Liftoff
The launch pad hold-down arms retract and the Soyuz rocket soars into the sky.

Data source: Arianespace