The following timeline was compiled by William Harwood, CBS News, from telemetry data (through revision 14 of NASA's internal timeline) and transcriptions of the NASA-Select commentary, mission control audio loops and portions of a 13-minute in-cabin video recovered after the accident. The relevant data sources were released by the Columbia Accident Investigation Board.
The telemetry timing is exact, but the mission control audio and commentary entries are approximations. All such entries are tied to the assumption that shuttle commander Rick Husband's final transmission began at 8:59:32 a.m. EST, the moment the last valid data frame was transmitted from the orbiter. Likewise, the crew cabin comments by the astronauts were timed off on the assumption the tape began at exactly 8:35 a.m., which is the time NASA gave in a press release.
Audio loop entries will be updated as warranted based on digital time stamps from the Johnson Space Center audio control center. As it stands, however, the audio loop entries are believed accurate to within a few seconds.
To prevent interrupting the telemetry/mission control narrative, the NASA commentator entries are presented in blocks, as they were spoken. Readers should note, however, other events may be happening while the commentator is talking, as reflected in the times listed for those events.
Most telemetry entries include altitude in feet, Mach number and latitude and longitude in parentheses with north (+) latitude first followed by west (-) longitude, i.e., +36.398-150.847 means 36.398 degrees north latitude, 150.847 degrees west longitude.
Personnel mentioned:
MCC-FLIGHT - Entry flight director - Leroy Cain, mission control center
MCC-CAPCOM - Astronaut Charles Hobaugh
MCC-FDO (Flight Dynamics Officer; pronounced "FIDO") - Richard Jones
MCC-INCO (Instrumentation and Communications Officer) - Laura Hoppe
MCC-MMACS (Maintenance, Mechanical, Arm and Crew Systems Officer) - Jeff Kling
MCC-GNC (Guidance, Navigation and Control Officer) - Mike Sarafin
MCC-GC (Ground Control Officer) - Bill Foster
MCC-GPO (Guidance and Procedures Officer) - Doyle Hensley
MCC-EECOM (Emergency, Environmental and Consumables Operation Manager) - Katie Rogers
MCC-LSO (Landing and Support Officer) - Martin Linde
MCC-MOD (Mission Operations Directorate Representative) - Phil Engelauf
MCC-Commentator - James Hartsfield, NASA/JSC public affairs officer
STS-A/G (Shuttle Commander, air-to-ground audio) - Shuttle commander Rick Husband, aboard Columbia
STS-ICOM - Indicates cockpit intercom voice traffic captured on in-cabin video
At KSC, all voice recordings are "tagged" with IRIG-B time, which is accurate to milliseconds. Don't know about JSC.
The time information embedded within the shuttle telemetry comes from the shuttle MTU [Master Timing Unit], which is accurate to a few parts in 10-12.