But more importantly.

The flight recorder system was manufactured in 1997 so it was an update for this particular recorder system.

The aircraft was built in 1991 and did not actually have a door sensor.

The FDR shows 0's for the flight door because it was an unused block.

Your thread topic has just been debunked.

Sorry.


you didn't debunk anything, you just showed how little you know, this is from pilots for the truth forum:


"The FLT DECK OPEN parameter was not added to the FDR frame (757-3 A2) until 1997. The plane was manufactured in 1991 using an earler frame structure which did not include the parameter, so a binary 0 for an unused data block."


This claim is wrong because actually all the FDR system has been updated before 08/18/2001...

According to [link to www.boeing.com]

Airplanes manufactured before October 11, 1991, without an FDAU or DFDAU as of July 16, 1996.
Airplanes manufactured before October 11, 1991, with an FDAU or DFDAU as of July 16, 1996.
Airplanes manufactured after October 11, 1991, after August 18, 2000, and after August 18, 2002.

AIRPLANES MANUFACTURED PRIOR TO OCTOBER 11, 1991, WITHOUT AN FDAU OR DFDAU INSTALLED AS OF JULY 16, 1996.
The new rule requires that by August 18, 2001 the FDR record at least 18 parameter groups. For most airplanes, this is an increase from 11 parameter groups, as described in "Effects of 1989 FAA Flight Data Recorder Rule Change" on page 32.

The new rule requires that by four years from date of rule at least 22 parameter groups be recorded by the FDR. In this group are Boeing models 727, 737, 747, 757, 767, DC-10, and MD-80.

Flight 77 = N644AA 2460

Certificate Issue Date 05/08/1991

[link to registry.faa.gov]

N644AA = AIRPLANES MANUFACTURED PRIOR TO OCTOBER 11, 1991

So N644AA has been updated before August 18, 2001





Not so fast:

The aircraft was manufactured before October 11 1991.

The rule for these aircraft is:

AIRPLANES MANUFACTURED PRIOR TO OCTOBER 11, 1991, WITHOUT AN FDAU OR DFDAU INSTALLED AS OF JULY 16, 1996.
The new rule requires that by August 18, 2001 the FDR record at least 18 parameter groups. For most airplanes, this is an increase from 11 parameter groups, as described in "Effects of 1989 FAA Flight Data Recorder Rule Change" on page 32. On about half of all the Boeing 727, 737, DC-8, and DC-9 models the FDR system uses a single FDR, a result of the late 1980s replacement activity. Most of these FDRs should have enough spare inputs to accommodate the increased requirements with little or no modification required. Other parameter groups required to be recorded include the addition of both flight control surface positions and flight control inputs for all three axes (lateral, directional, longitudinal), lateral acceleration, and autopilot engagement status. Airplanes manufactured prior to October 11, 1991, with a FDAU or DFDAU installed as of July 16, 1996. The new rule requires that by four years from date of rule at least 22 parameter groups be recorded by the FDR. In this group are Boeing models 727, 737, 747, 757, 767, DC-10, and MD-80. Most of these airplanes record almost all the 22 parameter groups, some of which operators may ask Boeing to remove to save weight or to avoid maintenance costs if a parameter group is not required by a particular country's regulatory agency. The additional parameter groups required to be recorded include the addition of flight control surface positions and flight control inputs for all three axes, lateral acceleration, and autopilot engagement status.

Let me repeat this:

The new rule requires that by August 18, 2001 the FDR record at least 18 parameter groups.

If you read the rest of it you will glean that later aircraft will require 34, 57, or 88 parameter groups to be recorded.

The door sensor is not required on the earlier aircraft but they COULD have a flight recorder installed that had the capacity for more parameters, but they were unused blocks.

Or possibly it might have had to record 22 parameters, but that is still much less than the 34, 55, or 88 parameter capable recorders.

Feel free to provide a list of EXACTLY what the required 22 parameters were.