{"schemaVersion":1,"recordId":"wtc7-observed-fire-progression-v1","reviewedDate":"2026-09-23","title":"The afternoon fires moved through the building","label":"NIST fire observations \u00b7 broad locations, approximate times","timeBasis":{"origin":"September 11, 2001, 12:00 noon EDT","unit":"minutes after noon","startMinute":120,"endMinute":320,"displayPrefix":"\u2248","meaning":"Civil-clock observation times. These are separate from thermal-model elapsed hours and collapse-solver seconds."},"coordinateSystem":{"u":"0 west, 1 east, interpolated across the registered trapezoid at each v","v":"0 north, 1 south","uAndVAre":"region center","sizeUAndSizeVAre":"full normalized rectangle widths","geometry":"Map all four rectangle corners bilinearly into the registered floor footprint.","verticalExtent":"Authored display height within the floor; no flame-height or temperature measurement."},"intensityMeaning":{"0":"Do not display active fire. Read evidenceStatus: either flames were not visible in a named area or no later observation locates them.","0.15":"Spot-fire emphasis, chosen for display.","0.35":"Diminished/low-flame emphasis, chosen for display.","0.7":"Visible-fire emphasis, chosen for display.","1":"Intense-flame emphasis, chosen for display.","physicalMeaning":"None of these numbers is heat release, gas temperature, steel temperature, flame volume, or a calibrated fire intensity."},"presentationLimits":["These boxes visualize the general progression described by NIST from exterior photographs and video. They are not NIST solver output or exact three-dimensional fire boundaries.","All box centers, widths, inward depths, transitions and display intensities are authored. Cardinal areas and approximate sequence come from the cited observations.","Interpolation between checkpoints illustrates direction only. The source often describes starts, stops, interior bypasses and gaps, so a smoothly moving box does not imply smooth fire spread.","A dark region means no active display cue. It does not prove the fire was extinguished or that its steel had cooled. Exterior views give limited information about the interior.","Separate region IDs prevent active blocks from travelling through major unobserved intervals. Explicit gap keys fade locations after their last report.","Floors 7\u20139 and 11\u201313 are the sustained-fire focus. This dataset does not claim that these were the only floors with any observed fire."],"rendererContract":{"sameId":"Interpolate center, full widths and display intensity between adjacent keys with the same region ID.","differentId":"Crossfade only; do not morph or travel between unrelated IDs.","emptyRegions":"No active fire volume at this key.","outsideTimeRange":"Clamp to the displayed 2:00\u20135:20 p.m. interval. Every floor has explicit endpoint keys.","captionPriority":"Show approximate clock plus the floor/key timeLabel; expose confidenceNote and cited observations in evidence view."},"sources":[{"id":"nist-1a-fire-account","label":"NIST NCSTAR 1A \u00b7 \u00a72.3, pp. 18\u201321","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=60"},{"id":"nist-1-9-fire-summary","label":"NIST NCSTAR 1-9 \u00b7 \u00a75.6.4, pp. 242\u2013246","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=286"},{"id":"nist-1-9-late-images","label":"NIST NCSTAR 1-9 \u00b7 \u00a75.6.3, pp. 230\u2013241","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=274"}],"floors":[{"floor":7,"generalDirection":"North along west face, then east along north face","observations":[{"id":"f7-west-onset","minute":122,"timeLabel":"Shortly after 2:00 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Fire appeared on the west side and spread north toward the northwest corner.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=61","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 61"},{"id":"f7-northwest-turn","minute":180,"timeLabel":"By about 3:00 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"The fire had turned the northwest corner and was spreading east across the north face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=61","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 61"},{"id":"f7-north-midpoint","minute":192,"timeLabel":"About 3:12 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"North-face flames reached Column 47, beyond the face midpoint, then stopped advancing.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=287","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 287"},{"id":"f7-early-flames-diminish","minute":195,"timeLabel":"About 3:15\u20134:15 p.m.","timePrecision":"approximate unless explicitly stated","status":"diminished_to_spots","text":"The larger flames died down. Small localized spot fires remained west of Column 47.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=287","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 287","minuteRange":[195,255]},{"id":"f7-late-north-return","minute":255,"timeLabel":"About 4:15\u20134:25 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Fire reappeared farther east; a larger fire developed east of Column 47 roughly ten minutes later.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=287","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 287","minuteRange":[255,265]},{"id":"f7-late-flames-diminish","minute":278,"timeLabel":"About 4:38\u20134:40 p.m.","timePrecision":"approximate unless explicitly stated","status":"diminished_and_later_unknown","text":"The new north-face flames had died down. No later images established the subsequent eastward progression.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=287","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 287"}],"visualKeys":[{"minute":120,"timeLabel":"2:00 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"The first localized west-face observation follows shortly after 2 p.m.; this is not a no-fire finding."},{"minute":122,"timeLabel":"Shortly after 2 p.m.","regions":[{"id":"f7-early","u":0.14,"v":0.62,"sizeU":0.28,"sizeV":0.32,"intensity":0.7,"observationIds":["f7-west-onset"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":170,"timeLabel":"Before 3 p.m.","regions":[{"id":"f7-early","u":0.14,"v":0.16,"sizeU":0.28,"sizeV":0.32,"intensity":0.7,"observationIds":["f7-west-onset","f7-northwest-turn"]}],"evidenceStatus":"authored_between_observations","confidenceNote":"Authored turning checkpoint within the reported west-to-north progression; 2:50 p.m. is not an independently observed arrival time."},{"minute":180,"timeLabel":"About 3:00 p.m.","regions":[{"id":"f7-early","u":0.28,"v":0.15,"sizeU":0.34,"sizeV":0.3,"intensity":0.7,"observationIds":["f7-northwest-turn"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":192,"timeLabel":"About 3:12 p.m.","regions":[{"id":"f7-early","u":0.57,"v":0.15,"sizeU":0.3,"sizeV":0.3,"intensity":0.7,"observationIds":["f7-north-midpoint"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":195,"timeLabel":"About 3:15 p.m.","regions":[{"id":"f7-early","u":0.57,"v":0.15,"sizeU":0.3,"sizeV":0.3,"intensity":0,"observationIds":["f7-early-flames-diminish"]},{"id":"f7-spots","u":0.47,"v":0.15,"sizeU":0.18,"sizeV":0.3,"intensity":0.15,"observationIds":["f7-early-flames-diminish"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"The larger perimeter flames died down; the small block represents residual spot fires, not continued uniform burning."},{"minute":255,"timeLabel":"About 4:15 p.m.","regions":[{"id":"f7-spots","u":0.47,"v":0.15,"sizeU":0.18,"sizeV":0.3,"intensity":0.15,"observationIds":["f7-early-flames-diminish"]},{"id":"f7-late","u":0.66,"v":0.15,"sizeU":0.22,"sizeV":0.3,"intensity":0,"observationIds":["f7-late-north-return"]}],"evidenceStatus":"authored_return_boundary","confidenceNote":"Display ramp begins around 4:15 p.m., when the fire returned east of Column 47; the larger fire is shown at the next 4:25 p.m. checkpoint. This zero starts the display transition, not a no-fire finding. It prevents the later eastern cue from appearing during the earlier period when NIST reports only localized spot fires west of Column 47."},{"minute":265,"timeLabel":"About 4:25 p.m.","regions":[{"id":"f7-spots","u":0.47,"v":0.15,"sizeU":0.18,"sizeV":0.3,"intensity":0,"observationIds":["f7-early-flames-diminish"]},{"id":"f7-late","u":0.71,"v":0.15,"sizeU":0.26,"sizeV":0.3,"intensity":0.7,"observationIds":["f7-late-north-return"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":278,"timeLabel":"About 4:38 p.m.","regions":[{"id":"f7-late","u":0.73,"v":0.15,"sizeU":0.26,"sizeV":0.3,"intensity":0,"observationIds":["f7-late-flames-diminish"]},{"id":"f7-late-spots","u":0.73,"v":0.15,"sizeU":0.12,"sizeV":0.3,"intensity":0.15,"observationIds":["f7-late-flames-diminish"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Larger flames had died down. NIST describes spot fires in the late north-face images; exact inward extent is unknown."},{"minute":285,"timeLabel":"After about 4:40 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"Authored fade after the last localized image. Missing blocks mean no later fire-location record, not extinction."},{"minute":320,"timeLabel":"About 5:20 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"No later localized imagery in this record; interior conditions are unknown."}]},{"floor":8,"generalDirection":"East across north face; later northwestern burning and flames at east face","observations":[{"id":"f8-north-no-fire","minute":202,"timeLabel":"About 3:22 p.m.","timePrecision":"approximate unless explicitly stated","status":"no_visible_fire_in_named_area","text":"No fire was indicated near the center of the north face in the available image.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=287","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 287"},{"id":"f8-north-onset","minute":219,"timeLabel":"About 3:39\u20133:40 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"A substantial fire was visible near the north-face center, spreading east.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=287","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 287"},{"id":"f8-west-north-return","minute":222,"timeLabel":"About 3:42 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Intense burning appeared near the north end of the west face. NIST inferred earlier interior spread had bypassed the northwest corner.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=287","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 287"},{"id":"f8-east-first-window","minute":null,"minuteRange":[233,242],"timeLabel":"Between 3:53 and 4:02 p.m.","timePrecision":"NIST estimated clip time interval; not an exact arrival time","status":"visible_fire","text":"A small flame appeared on the east face and grew more intense within seconds. The video clip is timed between 3:53 and 4:02 p.m.; intense east-face flames were filmed roughly two minutes later.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=271","sourceLabel":"NIST NCSTAR 1-9 \u00b7 pp. 227\u2013228 (PDF pp. 271\u2013272)"},{"id":"f8-east-arrival","minute":235,"timeLabel":"About 3:55 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"The north-face fire reached the east face, where intense external flames developed.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f8-north-diminish","minute":242,"timeLabel":"Soon after 4:00 p.m.","timePrecision":"approximate unless explicitly stated","status":"diminished_to_spots","text":"Visible burning near the north-face center died down; remaining small fires appeared deeper inside.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=287","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 287"},{"id":"f8-north-low","minute":250,"timeLabel":"About 4:10 p.m. \u00b1 at least 5 min","timePrecision":"approximate unless explicitly stated","status":"diminished_fire","text":"Low flames remained between windows 8-45E and 8-49B on the north face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=274","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 274"},{"id":"f8-north-low-later","minute":260,"timeLabel":"Roughly 4:20 p.m.","timePrecision":"approximate unless explicitly stated","status":"diminished_fire","text":"Low flames were still visible between Columns 47 and 49 on the north face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=275","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 275"},{"id":"f8-north-spots","minute":278,"timeLabel":"About 4:38 p.m.","timePrecision":"approximate unless explicitly stated","status":"diminished_to_spots","text":"Only small spot fires were visible in the recorded eastern portion of the north face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=277","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 277"}],"visualKeys":[{"minute":120,"timeLabel":"2:00 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"No localized early-afternoon fire path is established here for Floor 8."},{"minute":202,"timeLabel":"About 3:22 p.m.","regions":[{"id":"f8-north","u":0.5,"v":0.15,"sizeU":0.34,"sizeV":0.3,"intensity":0,"observationIds":["f8-north-no-fire"]}],"evidenceStatus":"no_visible_flame_checkpoint","confidenceNote":"Zero applies to visible north-center flames in this image, not the whole floor."},{"minute":219,"timeLabel":"About 3:40 p.m.","regions":[{"id":"f8-north","u":0.52,"v":0.15,"sizeU":0.34,"sizeV":0.3,"intensity":0.7,"observationIds":["f8-north-onset"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":222,"timeLabel":"About 3:42 p.m.","regions":[{"id":"f8-north","u":0.63,"v":0.15,"sizeU":0.36,"sizeV":0.3,"intensity":0.7,"observationIds":["f8-north-onset"]},{"id":"f8-northwest","u":0.12,"v":0.19,"sizeU":0.24,"sizeV":0.38,"intensity":1,"observationIds":["f8-west-north-return"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":233,"timeLabel":"Earliest bound of the east-face arrival clip","regions":[{"id":"f8-north","u":0.80769231,"v":0.15,"sizeU":0.32615385,"sizeV":0.3,"intensity":0.7,"observationIds":["f8-north-onset","f8-east-arrival"]},{"id":"f8-northwest","u":0.12,"v":0.19,"sizeU":0.24,"sizeV":0.38,"intensity":0.15384615,"observationIds":["f8-west-north-return"]},{"id":"f8-east","u":0.86,"v":0.23,"sizeU":0.28,"sizeV":0.32,"intensity":0,"observationIds":["f8-east-first-window","f8-east-arrival"]}],"evidenceStatus":"authored_arrival_boundary","confidenceNote":"An explicit display boundary prevents the separate east-face cue from fading in as early as 3:42 p.m. NIST NCSTAR 1-9 pp. 227\u2013228 dates the first east-face flame clip between 3:53 and 4:02 p.m.; 3:53 is the earliest bound, not a measured ignition time. The existing north-face interpolation is preserved."},{"minute":235,"timeLabel":"About 3:55 p.m.","regions":[{"id":"f8-north","u":0.84,"v":0.15,"sizeU":0.32,"sizeV":0.3,"intensity":0.7,"observationIds":["f8-east-arrival"]},{"id":"f8-east","u":0.86,"v":0.23,"sizeU":0.28,"sizeV":0.32,"intensity":1,"observationIds":["f8-east-arrival"]},{"id":"f8-northwest","u":0.12,"v":0.19,"sizeU":0.24,"sizeV":0.38,"intensity":0,"observationIds":["f8-west-north-return"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"The northwest display fades as evidence follows the eastern front; its exact burnout time was not observed."},{"minute":242,"timeLabel":"Soon after 4 p.m.","regions":[{"id":"f8-north-residual","u":0.65,"v":0.15,"sizeU":0.34,"sizeV":0.3,"intensity":0.15,"observationIds":["f8-north-diminish"]},{"id":"f8-east","u":0.86,"v":0.23,"sizeU":0.28,"sizeV":0.32,"intensity":0,"observationIds":["f8-east-arrival"]}],"evidenceStatus":"mixed_observation_and_display_fade","confidenceNote":"The eastern block fades after its last localized checkpoint; zero there is a display cutoff, not a measured extinction time."},{"minute":250,"timeLabel":"About 4:10 p.m.","regions":[{"id":"f8-north-residual","u":0.65,"v":0.15,"sizeU":0.28,"sizeV":0.3,"intensity":0.35,"observationIds":["f8-north-low"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":260,"timeLabel":"About 4:20 p.m.","regions":[{"id":"f8-north-residual","u":0.65,"v":0.15,"sizeU":0.2,"sizeV":0.3,"intensity":0.35,"observationIds":["f8-north-low-later"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Low north-face burning; the box recenters on the smaller surviving visible area, not a reverse-moving fire front."},{"minute":278,"timeLabel":"About 4:38 p.m.","regions":[{"id":"f8-north-spots","u":0.76,"v":0.15,"sizeU":0.14,"sizeV":0.3,"intensity":0.15,"observationIds":["f8-north-spots"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Small visible spots only; their placement is qualitative."},{"minute":285,"timeLabel":"After about 4:40 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"Authored fade after late localized observations. No new fire path is inferred."},{"minute":320,"timeLabel":"About 5:20 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"No later localized fire record is supplied here."}]},{"floor":9,"generalDirection":"East across north face","observations":[{"id":"f9-before-onset","minute":225,"timeLabel":"About ten minutes before first flames","timePrecision":"approximate unless explicitly stated","status":"no_visible_fire_in_named_area","text":"Earlier images gave no indication of fire in the later north-face ignition area.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=288","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 288"},{"id":"f9-northwest-onset","minute":235,"timeLabel":"Shortly before 4:00 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"A small fire appeared on the west side of the north face; its route to that location was not observed.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f9-north-center","minute":250,"timeLabel":"About 4:10 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Flames spread east to about the midpoint of the north face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f9-north-east","minute":260,"timeLabel":"About 4:20 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"The fire advanced about halfway from the midpoint toward the northeast corner; the western portion was dying down.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f9-north-spots","minute":278,"timeLabel":"About 4:38 p.m.","timePrecision":"approximate unless explicitly stated","status":"diminished_to_spots","text":"Only small spot fires remained visible in the eastern part of the north face. NIST found no evidence of later behavior after about 4:40 p.m.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=288","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 288"}],"visualKeys":[{"minute":120,"timeLabel":"2:00 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"No early localized fire path is documented for Floor 9."},{"minute":225,"timeLabel":"Before about 4 p.m.","regions":[{"id":"f9-north","u":0.23,"v":0.15,"sizeU":0.18,"sizeV":0.3,"intensity":0,"observationIds":["f9-before-onset"]}],"evidenceStatus":"no_visible_flame_checkpoint","confidenceNote":"No visible flames in the later north-face onset area. The exact pre-onset time is approximate."},{"minute":235,"timeLabel":"Shortly before 4 p.m.","regions":[{"id":"f9-north","u":0.23,"v":0.15,"sizeU":0.18,"sizeV":0.3,"intensity":0.35,"observationIds":["f9-northwest-onset"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"3:55 p.m. is an approximate display placement for \u201cshortly before 4\u201d; the route into this area is unknown."},{"minute":250,"timeLabel":"About 4:10 p.m.","regions":[{"id":"f9-north","u":0.47,"v":0.15,"sizeU":0.32,"sizeV":0.3,"intensity":0.7,"observationIds":["f9-north-center"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":260,"timeLabel":"About 4:20 p.m.","regions":[{"id":"f9-north","u":0.66,"v":0.15,"sizeU":0.38,"sizeV":0.3,"intensity":0.7,"observationIds":["f9-north-east"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":278,"timeLabel":"About 4:38 p.m.","regions":[{"id":"f9-north","u":0.77,"v":0.15,"sizeU":0.16,"sizeV":0.3,"intensity":0.15,"observationIds":["f9-north-spots"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":285,"timeLabel":"After about 4:40 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"Authored fade beyond the last recorded locations; later eastward spread is not shown as observed."},{"minute":320,"timeLabel":"About 5:20 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"Later fire positions are unknown in the selected observations."}]},{"floor":11,"generalDirection":"North along east face; separate later north-face observations","observations":[{"id":"f11-east-start","minute":128,"timeLabel":"About 2:08 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Flames were observed near the south end of the east face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f11-east-north","minute":148,"timeLabel":"About 2:28 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Over about twenty minutes, fire spread north to roughly the middle of the east face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f11-long-gap","minute":150,"timeLabel":"After about 2:30 p.m. for over two hours","timePrecision":"approximate unless explicitly stated","status":"no_visible_fire_with_unknown_interior","text":"Subsequent images showed no burning for over two hours. The route and arrival time of the later north-face fire were not established.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=288","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 288","minuteRange":[150,278]},{"id":"f11-north-first","minute":278,"timeLabel":"About 4:38 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"A fire appeared just east of the north-face center; NIST described eastward spread from the center.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f11-north-dies","minute":292,"timeLabel":"About 4:52 p.m.","timePrecision":"approximate unless explicitly stated","status":"no_visible_fire_in_named_area","text":"Visible flames in that north-face area had died down.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f11-north-return","minute":309,"timeLabel":"About 5:09 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Fire reappeared near the center of the north face around Column 49.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=288","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 288"},{"id":"f11-north-west-late","minute":319,"timeLabel":"About 5:19\u20135:20 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Fire spread west from the center. Near collapse, flames were visible between Columns 50 and 52, without reaching the northwest corner.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=284","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 284","minuteRange":[319,320.3]}],"visualKeys":[{"minute":120,"timeLabel":"2:00 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"The first localized east-face observation is at about 2:08 p.m."},{"minute":128,"timeLabel":"About 2:08 p.m.","regions":[{"id":"f11-east","u":0.86,"v":0.77,"sizeU":0.28,"sizeV":0.3,"intensity":0.7,"observationIds":["f11-east-start"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":148,"timeLabel":"About 2:28 p.m.","regions":[{"id":"f11-east","u":0.86,"v":0.51,"sizeU":0.28,"sizeV":0.36,"intensity":0.7,"observationIds":["f11-east-north"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":155,"timeLabel":"After about 2:30 p.m.","regions":[{"id":"f11-east","u":0.86,"v":0.51,"sizeU":0.28,"sizeV":0.36,"intensity":0,"observationIds":["f11-long-gap"]}],"evidenceStatus":"authored_gap_boundary","confidenceNote":"The 2:35 p.m. key is an authored fade into the documented visibility gap, not an exact burnout time."},{"minute":270,"timeLabel":"Before 4:38 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"No active block crosses the unobserved east-to-north interior route."},{"minute":278,"timeLabel":"About 4:38 p.m.","regions":[{"id":"f11-north-first","u":0.65,"v":0.15,"sizeU":0.3,"sizeV":0.3,"intensity":1,"observationIds":["f11-north-first"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":284,"timeLabel":"About 4:44 p.m.","regions":[{"id":"f11-north-first","u":0.72,"v":0.15,"sizeU":0.32,"sizeV":0.3,"intensity":0.7,"observationIds":["f11-north-first"]}],"evidenceStatus":"authored_between_observations","confidenceNote":"Authored short eastward progression between the approximately 4:38 p.m. appearance and the 4:52 p.m. decline."},{"minute":292,"timeLabel":"About 4:52 p.m.","regions":[{"id":"f11-north-first","u":0.72,"v":0.15,"sizeU":0.32,"sizeV":0.3,"intensity":0,"observationIds":["f11-north-dies"]}],"evidenceStatus":"no_visible_flame_checkpoint","confidenceNote":"The visible flames in this area had died down."},{"minute":306,"timeLabel":"Before about 5:09 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"The next observed flames are a separate appearance near north-center."},{"minute":309,"timeLabel":"About 5:09 p.m.","regions":[{"id":"f11-north-late","u":0.51,"v":0.15,"sizeU":0.2,"sizeV":0.3,"intensity":0.7,"observationIds":["f11-north-return"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":319,"timeLabel":"About 5:19 p.m.","regions":[{"id":"f11-north-late","u":0.38,"v":0.15,"sizeU":0.26,"sizeV":0.3,"intensity":0.7,"observationIds":["f11-north-west-late"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":320,"timeLabel":"About 5:20 p.m.","regions":[{"id":"f11-north-late","u":0.34,"v":0.15,"sizeU":0.28,"sizeV":0.3,"intensity":0.7,"observationIds":["f11-north-west-late"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."}]},{"floor":12,"generalDirection":"East side to north face, then west; interior bypasses inferred by NIST","observations":[{"id":"f12-east-start","minute":128,"timeLabel":"About 2:08 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Fire was first seen toward the south end of the east face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f12-east-branches","minute":150,"timeLabel":"About 2:30 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Earlier east-face flames diminished. Fire had spread south into the southeast corner and north about two-thirds of the way toward the northeast corner.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f12-north-appearance","minute":177,"timeLabel":"Just before 3:00 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire_with_inferred_route","text":"Fire appeared east of center on the north face. NIST inferred an interior route that initially bypassed the northeast corner.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=289","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 289"},{"id":"f12-north-fan","minute":192,"timeLabel":"Within about fifteen minutes of 3:00 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"North-face flames spread east to engulf the northeast corner and west about one-third of the way across the face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=62","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 62"},{"id":"f12-northwest-approach","minute":225,"timeLabel":"About 3:45 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"The fire advanced west in starts and stops, reaching the area near Columns 55 and 56 toward the northwest corner.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=289","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 289"},{"id":"f12-northwest-low","minute":260,"timeLabel":"Roughly 4:20 p.m.","timePrecision":"approximate unless explicitly stated","status":"diminished_fire_in_named_area","text":"Low flames were also visible between Columns 51 and 52; the images did not resolve the full western fire extent.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=275","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 275"},{"id":"f12-northwest-corner","minute":300,"timeLabel":"About 5:00 p.m. \u00b7 uncertainty at least ten minutes","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Flames were visible at the northwest corner. Available western views between the earlier and later images were limited.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=281","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 281","minuteRange":[290,310]}],"visualKeys":[{"minute":120,"timeLabel":"2:00 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"The first localized observation is near the southeast end of the east face at about 2:08 p.m."},{"minute":128,"timeLabel":"About 2:08 p.m.","regions":[{"id":"f12-east-leading","u":0.86,"v":0.72,"sizeU":0.28,"sizeV":0.38,"intensity":0.7,"observationIds":["f12-east-start"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":150,"timeLabel":"About 2:30 p.m.","regions":[{"id":"f12-east-leading","u":0.86,"v":0.39,"sizeU":0.28,"sizeV":0.36,"intensity":0.35,"observationIds":["f12-east-branches"]},{"id":"f12-southeast-return","u":0.86,"v":0.85,"sizeU":0.28,"sizeV":0.3,"intensity":0.35,"observationIds":["f12-east-branches"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":165,"timeLabel":"Between 2:30 and 3 p.m.","regions":[{"id":"f12-east-leading","u":0.86,"v":0.28,"sizeU":0.28,"sizeV":0.36,"intensity":0,"observationIds":["f12-east-branches"]},{"id":"f12-southeast-return","u":0.86,"v":0.85,"sizeU":0.28,"sizeV":0.3,"intensity":0,"observationIds":["f12-east-branches"]}],"evidenceStatus":"authored_gap_boundary","confidenceNote":"Authored fade before the next north-face observation. It does not assert an exact eastern burnout time or an observed route through the interior."},{"minute":177,"timeLabel":"Just before 3 p.m.","regions":[{"id":"f12-north-leading","u":0.73,"v":0.15,"sizeU":0.24,"sizeV":0.3,"intensity":0.7,"observationIds":["f12-north-appearance"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"A separate block marks north-face observation; no active block is carried across the inferred hidden interior route."},{"minute":192,"timeLabel":"By about 3:15 p.m.","regions":[{"id":"f12-north-leading","u":0.63,"v":0.15,"sizeU":0.32,"sizeV":0.3,"intensity":0.7,"observationIds":["f12-north-fan"]},{"id":"f12-northeast-return","u":0.86,"v":0.15,"sizeU":0.28,"sizeV":0.3,"intensity":0.7,"observationIds":["f12-north-fan"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":210,"timeLabel":"Between 3:15 and 3:45 p.m.","regions":[{"id":"f12-north-leading","u":0.4,"v":0.15,"sizeU":0.34,"sizeV":0.3,"intensity":0.7,"observationIds":["f12-north-fan","f12-northwest-approach"]},{"id":"f12-northeast-return","u":0.86,"v":0.15,"sizeU":0.28,"sizeV":0.3,"intensity":0,"observationIds":["f12-north-fan"]}],"evidenceStatus":"authored_between_observations","confidenceNote":"Authored progression between observed checkpoints. Continuous easing does not recreate the reported starts, stops or exact local burnout."},{"minute":225,"timeLabel":"About 3:45 p.m.","regions":[{"id":"f12-north-leading","u":0.2,"v":0.15,"sizeU":0.28,"sizeV":0.3,"intensity":0.7,"observationIds":["f12-northwest-approach"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":250,"timeLabel":"After 3:45 p.m.","regions":[{"id":"f12-north-leading","u":0.2,"v":0.15,"sizeU":0.28,"sizeV":0.3,"intensity":0,"observationIds":["f12-northwest-approach"]}],"evidenceStatus":"authored_gap_boundary","confidenceNote":"Authored fade where western views become limited; absence is a coverage gap, not a claim the northwest fire was extinguished."},{"minute":260,"timeLabel":"Roughly 4:20 p.m.","regions":[{"id":"f12-north-residual","u":0.35,"v":0.15,"sizeU":0.16,"sizeV":0.3,"intensity":0.35,"observationIds":["f12-northwest-low"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":278,"timeLabel":"Before about 5 p.m.","regions":[{"id":"f12-north-residual","u":0.35,"v":0.15,"sizeU":0.16,"sizeV":0.3,"intensity":0,"observationIds":["f12-northwest-low"]}],"evidenceStatus":"authored_gap_boundary","confidenceNote":"Authored fade of the last localized low-flame observation; no continuous western front is claimed."},{"minute":300,"timeLabel":"About 5:00 p.m.","regions":[{"id":"f12-northwest-late","u":0.1,"v":0.15,"sizeU":0.2,"sizeV":0.3,"intensity":0.7,"observationIds":["f12-northwest-corner"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"The source time is uncertain by at least ten minutes; this is a broad checkpoint rather than an exact ignition moment."},{"minute":315,"timeLabel":"After the last northwest observation","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"Authored fade after the approximately 5 p.m. image; no exact late burnout is established."},{"minute":320,"timeLabel":"About 5:20 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"The last localized Floor 12 fire shown here was near the northwest corner around 5 p.m.; its later extent is not resolved."}]},{"floor":13,"generalDirection":"North along east side, then west along north face","observations":[{"id":"f13-east-onset","minute":150,"timeLabel":"About 2:30 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"The first visible Floor 13 fire was on the east side.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=63","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 63"},{"id":"f13-east-untimed","minute":null,"timeLabel":"Somewhat later \u00b7 photograph untimed","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"An untimed photograph showed smoke and flames across much of the east face. Its exact position in the afternoon cannot be fixed.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=289","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 289"},{"id":"f13-northeast-north","minute":221,"timeLabel":"About 3:41 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire_with_inferred_route","text":"The fire had turned the northeast corner and reached about one-quarter of the way across the north face. The intervening spread was not directly documented.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=63","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 63"},{"id":"f13-north-midpoint","minute":242,"timeLabel":"Soon after 4:00 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Flames had spread at least to the midpoint of the north face.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1a.pdf#page=63","sourceLabel":"NIST NCSTAR 1A \u00b7 PDF p. 63"},{"id":"f13-east-north-dies","minute":278,"timeLabel":"About 4:38 p.m.","timePrecision":"approximate unless explicitly stated","status":"no_visible_fire_in_named_area","text":"Fires in the eastern portion of the north face had died down until flames were no longer observable there.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=289","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 289"},{"id":"f13-north-west-late","minute":300,"timeLabel":"About 5:00 p.m. \u00b7 uncertainty at least ten minutes","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Intense burning was seen west of the north-face center, near Columns 54 and 55.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=281","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 281","minuteRange":[290,310]},{"id":"f13-near-collapse-flames","minute":318,"timeLabel":"Within a few minutes of 5:20:52 p.m.","timePrecision":"approximate unless explicitly stated","status":"visible_fire","text":"Flames remained near the same western north-face area. Brief flame jets were also filmed, but their exact time and cause could not be established.","href":"https://nvlpubs.nist.gov/nistpubs/Legacy/NCSTAR/ncstar1-9.pdf#page=284","sourceLabel":"NIST NCSTAR 1-9 \u00b7 PDF p. 284","minuteRange":[317,320.87]}],"visualKeys":[{"minute":120,"timeLabel":"2:00 p.m.","regions":[],"evidenceStatus":"visibility_gap","confidenceNote":"The first localized Floor 13 fire in this record appears around 2:30 p.m."},{"minute":145,"timeLabel":"Before about 2:30 p.m.","regions":[{"id":"f13-east-north","u":0.86,"v":0.53,"sizeU":0.28,"sizeV":0.46,"intensity":0,"observationIds":["f13-east-onset"]}],"evidenceStatus":"authored_gap_boundary","confidenceNote":"Authored fade-in boundary; this does not establish the actual ignition time."},{"minute":150,"timeLabel":"About 2:30 p.m.","regions":[{"id":"f13-east-north","u":0.86,"v":0.53,"sizeU":0.28,"sizeV":0.46,"intensity":0.7,"observationIds":["f13-east-onset"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"The source establishes the east side, not an exact window-length flame front."},{"minute":180,"timeLabel":"Between 2:30 and 3:41 p.m.","regions":[{"id":"f13-east-north","u":0.86,"v":0.32,"sizeU":0.28,"sizeV":0.48,"intensity":0.7,"observationIds":["f13-east-onset","f13-east-untimed","f13-northeast-north"]}],"evidenceStatus":"authored_between_observations","confidenceNote":"Authored bridge along the reported general east-side route. The broad later east-face photograph is untimed; 3 p.m. is not a measured checkpoint."},{"minute":210,"timeLabel":"Approaching the northeast corner","regions":[{"id":"f13-east-north","u":0.86,"v":0.16,"sizeU":0.28,"sizeV":0.32,"intensity":0.7,"observationIds":["f13-northeast-north"]}],"evidenceStatus":"authored_between_observations","confidenceNote":"Authored turn toward the observed 3:41 p.m. north-face location; exact arrival time and interior path are unknown."},{"minute":221,"timeLabel":"About 3:41 p.m.","regions":[{"id":"f13-east-north","u":0.77,"v":0.15,"sizeU":0.32,"sizeV":0.3,"intensity":0.7,"observationIds":["f13-northeast-north"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":242,"timeLabel":"Soon after 4 p.m.","regions":[{"id":"f13-east-north","u":0.55,"v":0.15,"sizeU":0.36,"sizeV":0.3,"intensity":0.7,"observationIds":["f13-north-midpoint"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":278,"timeLabel":"About 4:38 p.m.","regions":[{"id":"f13-east-north","u":0.55,"v":0.15,"sizeU":0.4,"sizeV":0.3,"intensity":0,"observationIds":["f13-east-north-dies"]}],"evidenceStatus":"no_visible_flame_checkpoint","confidenceNote":"Zero marks the eastern north-face area where flames were no longer visible; it does not establish no fire elsewhere."},{"minute":290,"timeLabel":"Before the next western observation","regions":[{"id":"f13-northwest-late","u":0.26,"v":0.15,"sizeU":0.24,"sizeV":0.3,"intensity":0,"observationIds":["f13-north-west-late"]}],"evidenceStatus":"authored_gap_boundary","confidenceNote":"Authored fade-in boundary for the approximately 5 p.m. western image, whose time is uncertain."},{"minute":300,"timeLabel":"About 5:00 p.m.","regions":[{"id":"f13-northwest-late","u":0.26,"v":0.15,"sizeU":0.24,"sizeV":0.3,"intensity":1,"observationIds":["f13-north-west-late"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate checkpoint. Box size, inward depth and brightness are authored for visibility."},{"minute":318,"timeLabel":"Minutes before collapse","regions":[{"id":"f13-northwest-late","u":0.25,"v":0.15,"sizeU":0.24,"sizeV":0.3,"intensity":0.7,"observationIds":["f13-near-collapse-flames"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"The block represents continuing reported western-area burning. Brief jets are not recreated or synchronized with hidden structural failure."},{"minute":320,"timeLabel":"About 5:20 p.m.","regions":[{"id":"f13-northwest-late","u":0.25,"v":0.15,"sizeU":0.24,"sizeV":0.3,"intensity":0.7,"observationIds":["f13-near-collapse-flames"]}],"evidenceStatus":"observation_checkpoint","confidenceNote":"Approximate endpoint from near-collapse observations; no exact flame measurement is implied."}]}]}