This formula approximates the force that would be
exerted on an aircraft when it transitions from its downward path to level
First we determine the mass of the aircraft.
Flight 77, a Boeing 757, had taken off from Washington Dulles International
airport, and was bound for Los Angeles. Assuming its fuel tanks were full,
and ignoring the weight of the 64 passengers, and cargo (which should be
available if one wants to include them), the weight of the plane would be
about 255,000 pounds (Boeing
For our calculation we'll assume that weight and mass
are equal, i.e. 255,000 pounds.
For velocity we turn to the official account that Flight 77 struck the
Pentagon at "530 miles per hour" (The 9/11 Commission Report, p10).
For our calculation we'll assume that speed and velocity are
equal, i.e. 530 mph (speed is a scalar and velocity is a vector).
To calculate the radius, we could begin with a statement in The 9/11
Commission Report (p9): Flight 77 was "5 miles west-southwest of the
Pentagon" when it "began a 330-degree turn. At the end of turn, it was
descending through 2,200 feet".
Pilots for 9/11 Truth base their calculation on the Flight Data Recorder
obtained pursuant to a Freedom of Information Act request filed with the
National Transportation Safety Board, and carefully constructed topography of the area below the flight path.
Leaving aside the discrepancies between the official account of Flight 77,
and the Flight Data Recorder (which NTSB refuses to answer), Pilots for 9/11
Truth calculated a radius equal to about 579 feet.
From this they calculated the force on the Boeing 757 at 34 Gs, i.e. 34
times the force due to gravity.
There has been some criticism of the calculations performed by Pilots for
9/11 Truth, and they have answered
With mass, velocity, and radius equal to 255,000 lbs, 530 mph, and 579 feet
respectively, the preceding formula
yields force equal to 8,276,850 lbs, i.e. the Boeing 757 would act as if it
had increased its weight by 8,276,850 lbs, or more than 32 times its normal weight.
With a virtual weight of about 8.5 million pounds, Flight 77 could not have
levelled off before striking the Pentagon. It would have crashed before it
reached the Pentagon.
This fact alone is sufficient to refute the official account of "Flight 77."
Pilots for 9/11 Truth did another calculation
by lowering the height of "Flight 77" below that shown by the FDR. They
lowered it to to the top of the Virginia Department of Transportation
communications antenna that sits below the alleged flight path.
With this very conservative case, they calculated the force on the Boeing
757 at 11.2 Gs. "11.2 Gs was never recorded in the FDR. 11.2 Gs would rip
the aircraft apart" they state.
Frank Legge and David Chandler, Scientists for 9/11 Truth, do not take into account the 4-storeyNavy Annex on the north side of
Columbia Pike (its southeast corner is at
an elevation of 124 feet) and the gas station and
electric power line west of the Pentagon. These appear to be higher than the flight path
calculated by Legge and Chandler, which even if theoretically possible, is at least an
order of magnitude more difficult than striking the Pentagon from the east. Stiking from the east
is likely to inflict more damage to top military commanders whose offices overlook the
Potomac River on the eastern side of the Pentagon.
Frank Legge and David Chandler ignore the overwhelming evidence against their conclusion. Their analysis
requires one more step: calculating the probability that Hani Hanjour could fly a Boeing
757 in a spiral turn from 7000 feet along their calculated flight path to strike the western
wall of the Pentagon between the first and second floor as described in the Pentagon
Building Performance Report.
can prove a theory wrong, by establishing facts that are
inconsistent with the theory. In contrast, evidence cannot prove a
theory correct because other evidence, yet to be discovered, may exist that
is inconsistent with the theory."