| L-1 Day to L-10 Hours |
Falcon Heavy to Vertical |
| L-10:00:00 |
Countdown Initiation, Launch Vehicle Power-Up |
| L-6:00:00 |
First Weather Balloon Release |
| L-4:45:00 |
Range Controllers on Station |
| L-4:35:00 |
Attitude Control System N2 Loading |
| L-2:30:00 |
Launch Area Evacuation |
| L-2:30:00 |
Launch Vehicle Release System Test |
| L-2:25:00 |
TEA-TEB Bleed In |
| L-2:00:00 |
RF Link & FTS Checks (Round 2) |
| L-1:55:00 |
Data Flow Tests with Downrange Tracking Stations |
| L-1:45:00 |
Blast Danger Area Clear, Roadblocks Established |
| L-1:45:00 |
Propellant Load Setup (Transfer Lines Chill, Tank Vent) |
| L-1:40:00 |
Eastern Range Holdfire Checks |
| L-1:35:00 |
Weather Briefing |
| L-1:28:00 |
Launch Readiness Poll |
| T-1:25:00 |
Automated Countdown Sequence |
| T-1:25:00 |
Rocket Propellant 1 Loading |
| T-0:55:00 |
Flight Control System Setup (Flight Software Loading) |
| T-0:47:00 |
Go/No Go for LOX Load |
| T-0:45:00 |
Boosters/Core Stage Liquid Oxygen Loading |
| T~0:41:00 |
Stage 1 LOX Fast Fill |
| T-0:28:00 |
Range Readiness Check (Air Force & Coast Guard) |
| T-0:25:00 |
Spacecraft to Internal Power (Variable Time) |
| T-0:20:00 |
Second Stage LOX Load (S1 Throttle Down) |
| T-0:18:00 |
Second Stage Helium Load |
| T~0:13:00 |
1st Stage LOX Load in Pre-Topping |
| T-0:13:00 |
Countdown Recycle Point |
| T-0:12:45 |
Merlin 1D & MVac BTV Activation |
| T-0:10:15 |
Grid Fin Actuators Secured |
| T-0:10:05 |
Boostback Hazards Disabled |
| T-0:09:50 |
Flight Software Final Setups complete |
| T-0:09:45 |
TEA-TEB Ignition System Setup |
| T-0:09:45 |
Stage 2 Transmitter Re-Activation |
| T-0:09:00 |
M1D Trim Valve Setup Complete |
| T-0:08:00 |
M1D & MVac Hydraulic Pressurization |
| T-0:08:00 |
MVac Fuel Trim Valve Setup |
| T-0:07:35 |
M1D Engines to TVC-Null Position |
| T-0:07:30 |
Engine Chill Readiness |
| T-0:07:05 |
Stage 1 Helium Cushion Secured |
| T-0:07:00 |
Spacecraft on Internal Power |
| T-0:06:45 |
Engine Chilldown (Bleed Valves Open, both Stages) |
| T-0:06:30 |
M1D/MVac Hydraulics at Bleed Pressure |
| T-0:06:15 |
MVac Fuel Trim Valve Motions |
| T-0:06:00 |
Fuel Top-Up Flight Level |
| T-0:05:30 |
MVac FTV Motions complete |
| T-0:05:30 |
Flight Computers in Self-Alignment |
| T-0:05:20 |
Stage 1 Fuel Loading Complete |
| T-0:05:10 |
Launch Vehicle Heater Deactivation |
| T-0:05:00 |
Preliminary Tank Pressurization for Strongback Release |
| T-0:05:00 |
Transfer to Internal Power |
| T-0:05:00 |
Range Voice Checks |
| T-0:04:45 |
Stage 2 Thrust Vector Control Test |
| T-0:04:40 |
Stage 1 Helium Secured |
| T-0:04:30 |
Stage 2 RP-1 Bleed |
| T-0:04:00 |
Strongback Priming for Rapid Retract |
| T-0:04:00 |
Vehicle Release Auto Sequence |
| T-0:03:45 |
Stage 2 TVC Motions Complete |
| T-0:03:40 |
Ground Hydraulics Securing |
| T-0:03:25 |
Flight Termination System to Internal Power |
| T-0:03:00 |
FTS on Internal |
| T-0:03:00 |
Stage 1 POGO Bleed Verification |
| T-0:02:55 |
Verify Good Mvac TVC |
| T-0:02:45 |
Fuel Trim Valve to Flight Position |
| T-0:02:40 |
Stage 1 LOX Secure at Flight Level |
| T-0:02:30 |
Mvac Fuel Bleed Complete |
| T-0:02:25 |
Igniter Purge Complete |
| T-0:02:20 |
Strongback Secure for Launch 88.5° |
| T-0:02:25 |
Mvac Bleed Valve Motions |
| T-0:02:00 |
Stage 2 LOX Secure at Flight Level (Latest) |
| T-0:02:00 |
Transfer to Internal Power Complete |
| T-0:01:45 |
M1D Fuel Bleed Complete |
| T-0:01:35 |
Prop GSE Securing |
| T-0:01:30 |
Self-Align Verification |
| T-0:01:30 |
Final Engine Chilldown |
| T-0:01:25 |
Final Gas Close Outs (Helium termination) |
| T-0:01:15 |
Engine Chilldown Complete |
| T-0:01:10 |
Final FTS/AFSS Status Check |
| T-0:01:00 |
Flight Computer to start-up |
| T-0:00:45 |
Launch Director: Go for Launch |
| T-0:00:40 |
Stage 1, Stage 2 Pressurization for Flight |
| T-0:00:30 |
HOLD Call for Abort |
| T-0:00:15 |
Vehicle Configured for Flight |
| T-0:00:10 |
Latest VC Abort |
| T-0:00:07 |
Pad Deck Water Deluge System Activation |
| T-0:00:05 |
Side Booster Ignition Sequence Start |
| T-0:00:03 |
Core Stage Ignition Sequence Start |
| T-0:00:00 |
Strongback Kickback at Liftoff |
| T-0:00:00 |
LIFTOFF |
