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

Last Updated Sunday, January 29 2006 @ 10:38 AM MST