SEQUENCE OF MAJOR EVENTS OF THE CHALLENGER ACCIDENT Mission Time Elapsed (GMT, in hr:min:sec) Event Time (secs.) Source 16:37:53.444 ME-3 Ignition Command -6.566 GPC 37:53.564 ME-2 Ignition Command -6.446 GPC 37:53.684 ME-1 Ignition Command -6.326 GPC 38:00.010 SRM Ignition Command (T=0) 0.000 GPC 38:00.018 Holddown Post 2 PIC firing 0.008 E8 Camera 38:00.260 First Continuous Vertical Motion 0.250 E9 Camera 38:00.688 Confirmed smoke above field joint on RH SRM 0.678 E60 Camera 38:00.846 Eight puffs of smoke (from 0.836 thru 2.500 sec MET) 0.836 E63 Camera 38:02.743 Last positive evidence of smoke above right aft SRB/ET attach ring 2.733 CZR-1 Camera 38:03.385 Last positive visual indication of smoke 3.375 E60 Camera 38:04.349 SSME 104% Command 4.339 E41M2076D 38:05.684 RH SRM pressure 11.8 psi above nominal 5.674 B47P2302C 38:07.734 Roll maneuver initiated 7.724 V90R5301C 38:19.869 SSME 94% Command 19.859 E41M2076D 38:21.134 Roll maneuver completed 21.124 VP0R5301C 38:35.389 SSME 65% Command 35.379 E41M2076D 38:37.000 Roll and Yaw Attitude Response to Wind (36.990 to 62.990 sec) 36.990 V95H352nC 38:51.870 SSME 104% Command 51.860 E41M2076D 38:58.798 First evidence of flame on RH SRM 58.788 E207 Camera 38:59.010 Reconstructed Max Q (720 psf) 59.000 BET 38:59.272 Continuous well defined plume on RH SRM 59.262 E207 Camera 38:59.763 Flame from RH SRM in +Z direction (seen from south side of vehicle) 59.753 E204 Camera 39:00.014 SRM pressure divergence (RH vs. LH) 60.004 B47P2302 39:00.248 First evidence of plume deflection, intermittent 60.238 E207 Camera 39:00.258 First evidence of SRB plume attaching to ET ring frame 60.248 E203 Camera 39:00.998 First evidence of plume deflection, continuous 60.988 E207 Camera 39:01.734 Peak roll rate response to wind 61.724 V90R5301C 39:02.094 Peak TVC response to wind 62.084 B58H1150C 39:02.414 Peak yaw response to wind 62.404 V90R5341C 39:02.494 RH outboard elevon actuator hinge moment spike 62.484 V58P0966C 39:03.934 RH outboard elevon actuator delta pressure change 63.924 V58P0966C 39:03.974 Start of planned pitch rate maneuver 63.964 V90R5321C 39:04.670 Change in anomalous plume shape (LH2 tank leak near 2058 ring frame) 64.660 E204 Camera 39:04.715 Bright sustained glow on sides of ET 64.705 E204 Camera 39:04.947 Start SSME gimbal angle large pitch variations 64.937 V58H1100A 39:05.174 Beginning of transient motion due to changes in aero forces due to plume 65.164 V90R5321C 39:06.774 Start ET LH2 ullage pressure deviations 66.764 T41P1700C 39:12.214 Start divergent yaw rates (RH vs. LH SRB) 72.204 V90R2528C 39:12.294 Start divergent pitch rates (RH vs. LH SRB) 72.284 V90R2525C 39:12.488 SRB major high-rate actuator command 72.478 V79H2111A 39:12.507 SSME roll gimball rates 5 deg/sec 72.497 V58H1100A 39:12.535 Vehicle max +Y lateral acceleration (+.227 g) 72.525 V98A1581C 39:12.574 SRB major high-rate actuator motion 72.564 B58H1151C 39:12.574 Start of H2 tank pressure decrease with 2 flow control valves open 72.564 T41P1700C 39:12.634 Last state vector downlinked 72.624 Data reduction 39:12.974 Start of sharp MPS LOX inlet pressure drop 72.964 V41P1330C 39:13.020 Last full computer frame of TDRS data 73.010 Data reduction 39:13.054 Start of sharp MPS LH2 inlet pressure drop 73.044 V41P1100C 39:13.055 Vehicle max -Y lateral accelerarion (-.254 g) 73.045 V98A1581C 39:13.134 Circumferential white pattern on ET aft dome (LH2 tank failure) 73.124 E204 Camera 39:13.134 RH SRM pressure 19 psi lower than LH SRM 73.124 B47P2302C 39:13.147 First hint of vapor at intertank E207 Camera 39:13.153 All engine systems start responding to loss of fuel and LOX inlet pressure 73.143 SSME team 39:13.172 Sudden cloud a long ET between intertank and aft dome 73.162 E207 Camera 39:13.201 Flash between Orbiter & LH2 tank 73.191 E204 Camera 39:13.221 SSME telemetry data interference from 73.211 to 73.303 73.211 39:13.223 Flash near SRB fwd attach and brightening of flash between Orbiter and ET 73.213 E204 Camera 39:13.292 First indication intense white flash at SRB fwd attach point 73.282 E204 Camera 39:13.337 Greatly increased intensity of white flash 73.327 E204 Camera 39:13.387 Start RCS jet chamber pressure fluctuations 73.377 V42P1552A 39:13.393 All engines approaching HPFT discharge temp redline limits 73.383 E41Tn010D 39:13.492 ME-2 HPFT disch. temp Chan. A vote for shutdown; 2 strikes on Chan. B 73.482 MEC data 39:13.492 ME-2 controller last time word update 73.482 MEC data 39:13.513 ME-3 in shutdown due to HPFT discharge temperature redline exceedance 73.503 MEC data 39:13.513 ME-3 controller last time word update 73.503 MEC data 39:13.533 ME-1 in shutdown due to HPFT discharge temperature redline exceedance 73.523 Calculation 39:13.553 ME-1 last telemetered data point 73.543 Calculation 39:13.628 Last validated Orbiter telemetry measurement 73.618 V46P0120A 39:13.641 End of last reconstructured data frame with valid synchronization and frame count 73.631 Data reduction 39:14.140 Last radio frequency signal from Orbiter 74.130 Data reduction 39:14.597 Bright flash in vicinity of Orbiter nose 74.587 E204 Camera 39:16.447 RH SRB nose cap sep/chute deployment 76.437 E207 Camera 39:50.260 RH SRB RSS destruct 110.250 E202 Camera 39:50.262 LH SRB RSS destruct 110.252 E230 Camera ACT POS -- Actuator Position APU -- Auxilixary Power Unit BET -- Best Estimated Trajectory CH -- Channel DISC -- Discharge ET -- External Tank GG -- Gas Generator GPC -- General Purpose Computer GMT -- Greenwich Mean Time HPFT -- High Pressure Fuel Turbopump LH -- Lefthand LH2 -- Liquid Hydrogen LO2 -- Liquid Oxygen (same as LOX) MAX Q -- Maximum Dynamic Pressure ME -- Main Engine (same as SSME) MEC -- Main Engine Controller MET -- Mission Elapsed Time MPS -- Main Propulsion System PC -- Chamber Pressure PIC -- Pyrotechnics Initiator Controller psf -- Pounds per square foot RCS -- Reaction Control System RGA -- Rate Gyro Assembly RH -- Righthand RSS -- Range Safety System SRM -- Solid Rocket Motor SSME -- Space Shuttle Main Engine TEMP -- Temperature TVC -- Thrust Vector Control NOTE: The Shuttle coordinate system used is relative to the Orbiter, as follows: +X direction = forward (tail to nose) -X direction = rearward (nose to tail) +Y direction = right (toward the right wing tip) -Y direction = left (toward the left wing tip) +Z direction = down -Z direction = up