10:00 a.m. September 11, 2001: Alarm System Detects a Possible Fire in WTC 7

The fire alarm system in World Trade Center Building 7 detects a possible fire somewhere in the building, although the exact location of this possible fire is not signified. The alarm system has been placed on “test condition,” which causes any alarms to be ignored, for a period of eight hours, beginning at 6:47 a.m. this morning (see 6:47 a.m.-2:47 p.m. September 11, 2001). [National Institute of Standards and Technology, 6/2004, pp. 28] But less than two minutes after the South Tower collapsed (see 9:59 a.m. September 11, 2001), while it is in this condition, the system registers an alarm. This does not necessarily mean there is a fire in the building, however. “Even though a fire alarm is indicated,” a report by the National Institute of Standards and Technology (NIST) will later comment, “the record might have been the result of dust entering smoke detectors.” The alarm record will show that the fire condition occurs in “AREA 1.” However, NIST will be informed that AREA 1 is not a specific area within WTC 7, but instead refers to the entire building. This means that “a fire detected in any fire alarm zone in the building would have resulted in the same AREA 1 identification,” NIST will state. While the alarm system is in test condition, as is currently the case, records of an alarm are recorded in its history file but alarm signals do not appear on the operator’s display. And NIST will state that none of the interviews conducted by its investigation team, which examines the collapse of WTC 7, “contained any mention of an alarm received at the fire command station” in the building’s third-floor lobby. [National Institute of Standards and Technology, 11/2008, pp. 68-70]