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 Vertical Acceleration Final Second, G Forces from :44-:45
Posted: Sep 28 2006, 08:59 PM

LGA Patriot
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I have analyzed further Flight Data Recorder Parameters in terms of vertical speed vs. G Forces to see if there was any indication of this aircraft pulling level to cross the lawn (should the aircraft be low enough to hit the poles). One of the only parameters we have from :44-:45 is G Force. All other parameters stop recording at :44.

Working from a normal airspeed below Vmo (where we know definitely there are no "errors") to the final second of recorder data we have a descent rate of 4637 fpm. This descent rate is not excessive to cause lag in the altimeter.

The descent rate did get up to 6300 fpm at the :32 second of recorded data. This was the highest descent rate. The G Forces here were at .8 G's.

While leveling to a 4900 fpm descent rate at :37 seconds, the aircraft pulled 1.6 G's at top vertical acceleration. So, in plain english, the aircraft needed 5 seconds and pulling 1.6 G's to slow the descent rate by 1400 fpm. This is a benchmark number.

At the :39 second of recording, the aircraft was descending increasing rate to 5,760 fpm. Then the aircraft pulled 1.7 G's (top force) to slow the descent rate to 3960 fpm at the final second of data :44. So this aircraft took 5 seconds and 1.7 G's to slow descent rate by 1800 fpm. Pretty much in line with above analysis.

The G's are recorded till supposed impact time of :45. We do not have altitude data for the :45 impact time. The G's were less than 1 G for that final second. Meaning, the aircraft was increasing its descent rate for that last second :44-:45 from 3960 fpm and higher. It should have been leveling and pulling out of the dive if it were just above the lawn. If the aircraft were higher, the data makes sense.

Conclusion: This is in direct conflict with the DoD Video and completely impossible to have this descent rate if the aircraft was low enough to hit the poles. If the aircraft was low enough to hit the poles.. it would have dug itself into the ground with this descent rate after the :44 second. The Vertical acceleration (G Forces) actiing on the aircraft would need more than 10 seconds at 1.7 G's to pull out of that dive. Or, it would need to pull more than 17 G's in 1 second to pull out. Impossible for the airframe. The wings would have ripped off.

In order to be level across the lawn, the aircraft should have started its correction (pull out of dive) at the :35 mark or before based on the G Forces recorded. It did not.

The FDR is consistent through all parameters i have checked thus far that AA77 did not hit the light poles.

Altitude, Vertical Speed, System indications, G Forces, Alternate Analysis working back from the poles based on vertical speed alone... etc.

Go here to download the csv file if you would like to cross check yourself.
Posted: Oct 6 2006, 10:09 PM

LGA Patriot
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At 09:37:42 The Flight Data Recorder was descending at 5520 fpm. The Flight Data Recorder shows .7 G's being pulled between :42 and :43 (1.7 G's total, 1 G is normal gravity and is the zero point). At 09:37:43 the descent rate had slowed by 1440 fpm to 4080 fpm. 1440 fpm is 24 ft/sec. 32 ft/sec^2 is acceleration due to gravity. 24/32=.75. The FDR cross checks with the math.

The FDR shows the aircraft pulling 1.7 G's at top force to slow the descent rate by 1440 fpm.

At :44 the descent rate was 3980 fpm. The average G's pulled between :43-:44 was 1.04 G's. The FDR shows .04 G's needed to slow descent rate by 100 fpm. Makes sense.

From the :44 time stamp to impact time of :45, the average G's were .66 G's. .66x32ft/sec^2=21ft/sec increase in vertical speed. 21ft/secx60=1267 fpm increase in descent rate from :44-:45 official impact time.

3980 as shown at :44 plus 1267 fpm increase in descent rate = 5247 fpm descent rate for the last second :44-:45 data.

Conclusion - This descent rate is impossible to have been accomplished if the aircraft was low enough to hit the poles. It would have dug itself into the ground long before getting to the pentagon. 5247fpm is also not enough to have hit the pentagon from the altitude recorded by the Flight Data Recorder.

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