COLLAPSE ZONE
The structural collapse occurred at 9:57 a.m., 19 minutes after the impact. In the rescue industry it
is known as a "lean-to" collapse because of its one-sided nature. It took place at an expansion joint where the walls
and floors of the seam were not connected by rebar to allow for the expansion/contraction of the structure. It literally just
"slipped away". In this section we'll focus mostly on the debris found here as well as some damage evidence. Since we didn't find
significant wreckage outside the Pentagon, we'll start in the collapse zone and follow the aircraft path through the building
to the exit hole in the A-E drive.
Within the first second after impact, the American Airlines Boeing 757 penetrated 310 feet into the
Pentagon’s west wing corridors.........“The entire aircraft disintegrated rapidly as it moved through the forest of
columns on the first floor,” said Mlaker, who headed the team of structural, forensic and fire and blast damage experts.
(Source).
"Early Friday morning, shortly before 4 a.m., Burkhammer and another firefighter, Brian Moravitz
were combing through debris near the impact site. Peering at the wreckage with their helmet lights, the two spotted
an intact seat from the plane's cockpit with a chunk of the floor still attached. Then they saw two odd-shaped dark
boxes, about 1.5 by 2 feet long. They'd been told the plane's "black boxes" would in fact be bright orange, but
these were charred black. The boxes had handles on one end and one was torn open. They cordoned off the area and
called for an FBI agent, who in turn called for someone from the National Transportation Safety Board (NTSB) who confirmed
the find: the black boxes from AA Flight 77."
Newsweek
"Pentagon officials said the recorders, also called "black boxes" were found around 3:40 a.m.
under mounds of wreckage in the collapsed part of the building, where only a few pieces of the plane remain."
(The Washington Times September 15, 2001, Saturday, Final Edition Section: Part C; Metropolitan Pg. C1)
Black boxes - an aircraft's flight data recorder (FDR) and cockpit voice recorder (CVR) - are
two of the most important contributions to air safety since the beginning of the era of commercial flights.
The data collection devices - which are actually orange - are mounted in the tail of an aircraft.
BBC News
In conclusion we have confirmed eyewitness reports of pieces of the cockpit (front of aircraft) and the "black boxes"
(rear of aircraft) found "near the impact site".
The NTSB said in regards to the cockpit voice recorder, "It was quickly transported across the Potomac to the NTSB lab in Washington, D.C.,
where Cushman works with three other analysts, and its data was downloaded".
(Source)
The director of the FBI Robert Mueller said, "the agency had not gotten any information
from the voice data recorder from Flight 77".
(Source)
