The Two Baro Corrections Options

[wstutt]

Since I am not a pilot and have never flown a plane, I have a question.

I see there are two Barometer Correction columns in the NTSB's CSV file for AAL77 named "BARO COR NO. 1 (IN) (inHg)" and "BARO COR NO. 2 (IN) (inHg)" and that they appear to be independent of each other. Does that mean that the captain and first officer each have their own pressure altitude gauge and that these columns are showing the corrections for true altitude set by the captain and first officer on their own gauges independently of each other?

This post has been edited by wstutt: Jun 19 2008, 05:32 AM

[rob balsamo]

yes

[wstutt]

Thanks Rob,

I notice that in the NTSB CSV files, at about 9:24:16 EDT, both Baro Corrections are increased from about 29.92 to about 30.24. According to the government's story, Hani Hanjour was flying the plane at that time.

I would have thought that Hani Hanjour would have been operating one set of controls, either the captain's or the first officer's. So why would have both Baro Corrections have been changed at that time (unless of course the government's story is wrong)?

Warren.

[hiram]

On the existence of FRD

I have read of fair quantity of posts on PFT, some of them most interesting, I also have looked trought videos in particular that one on the flight path of AA77.
My native language beeing french, I am afraid I did'nt fully understand all the explanations given by competent professionals.

Of what I have gathered, it seems that AA77 flew to low by datas given by the FAA due to a bad calibration of its altimeter.

We arrive at a "Alice in Wonderland" situation where a plane seems to hit the pentagon but instead just flies over it and disappears into oblivion in the same time as it drops its flight recorders at a convenient place for the authorities to find.

If AA77 really flew the "corrected" way it must have landed somewhere (or beeing shot down in the best national interest), once the FDRs recovered, the encased datas duly edited could be released to the public.

If AA77 flew directly to another place, one had to "invent" datas ab nihilo. Same if AA77 did'nt exist at all.


The sole rational conclusion to which I am now able to reach is that the datas provided by the FAA are false.
It is then illusory to find in them a usefull information regarding AA77.

If explanations on this theme exists, I would be interested to learn of them.


One of your recent posts examine the fact that AA77 could have cut light poles after an skillfull and risqué manœuvre. As I am not an aviation professionnal I would know at what ultimate low altitude an aircraft such as AA77 can fly at ± 460 mph without incurring major damages due to ground effect.

Thanks in advance.



Hiram

[dMz]

As an aside, highly relevant to this thread,

if anyone really wants to delve into the technical/scientific aspects of pressure measurement and gauge response (times), one must discuss conductance:

http://www.tau.ac.il/~phchlab/experiments/...ime_vacuum.html

http://www.lesker.com/newweb/Technical_Inf...ctance_Calc.cfm

Of course, I don't remember any of our MSM/OGCT loyalist "debunkers" ever using this word before. Hmmm....

We'd need some verifiable Boeing or barometer manufacturer specific data to continue here.

[simba]

On the existence of FRD

I have read of fair quantity of posts on PFT, some of them most interesting, I also have looked trought videos in particular that one on the flight path of AA77.
My native language beeing french, I am afraid I did'nt fully understand all the explanations given by competent professionals.

Of what I have gathered, it seems that AA77 flew to low by datas given by the FAA due to a bad calibration of its altimeter.

We arrive at a "Alice in Wonderland" situation where a plane seems to hit the pentagon but instead just flies over it and disappears into oblivion in the same time as it drops its flight recorders at a convenient place for the authorities to find.

If AA77 really flew the "corrected" way it must have landed somewhere (or beeing shot down in the best national interest), once the FDRs recovered, the encased datas duly edited could be released to the public.

If AA77 flew directly to another place, one had to "invent" datas ab nihilo. Same if AA77 did'nt exist at all.


The sole rational conclusion to which I am now able to reach is that the datas provided by the FAA are false.
It is then illusory to find in them a usefull information regarding AA77.

If explanations on this theme exists, I would be interested to learn of them.


One of your recent posts examine the fact that AA77 could have cut light poles after an skillfull and risqué manœuvre. As I am not an aviation professionnal I would know at what ultimate low altitude an aircraft such as AA77 can fly at ± 460 mph without incurring major damages due to ground effect.

Thanks in advance.



Hiram

For me it's quit simple, the radio barometer altitude was 273ft prior to impact... Is for me much more saying then the normal pressure altitude you normaly getting with the altimeter settings knob...

[SPreston]

For me it's quit simple, the radio barometer altitude was 273ft prior to impact... Is for me much more saying then the normal pressure altitude you normaly getting with the altimeter settings knob...

The MSL of the Helipad at the Pentagon is 39 ft, so if the FDR aircraft radio barometer altitude was 273 ft MSL, then it was 134 feet too high to hit the Pentagon 1st floor.

[phaeton666]

The MSL of the Helipad at the Pentagon is 39 ft, so if the FDR aircraft radio barometer altitude was 273 ft MSL, then it was 134 feet too high to hit the Pentagon 1st floor.

This may be stupid questions from a simulator pilot, but to which value did the "pilots" set the baro? Was this value correct for the weather situation? Where did they know this value from? Did they tune in some ATIS?
And most importantly, why did they do it? If I want to crash into a building, I don't care for instruments, especially with near perfect visibility. Usually I would need to set the baro if I want to fly an altitude below FL180 correctly, or if I want to set up my FMS for a landing.
Don't know about real pilots, maybe this is so automatic that no one thinks about this, but somehow I don't believe it.

Very strange.
Phaeton666

[rob balsamo]

273 Ft was recorded by the FDR off the Radar Altimeter. This altitude is above ground level, not MSL or Sea Level.

And yes, the "hijackers" would have had to get the altimeter setting from somewhere eg ATIS, listening on radio... etc.