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Fdr Vertical Speed, Altimeter lag issues addressed as well.

rob balsamo
post Oct 15 2006, 08:41 AM
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We all know the Dept of Defense video shows an object going level across the lawn. So "debunkers" have tried to offer the theory that the FDR altimeter may be lagging due to pressure differentials. I have plotted the last few seconds side by side to address this issue based on the FDR data.

Please remember the following altitudes are from the csv file and reflect Pressure altitude. You need to add 300 feet to get the actual altitude of the aircraft.

09:37:42 AM 307

09:37:43 AM 239

09:37:44 AM 173

09:37:45 AM
09:37:46 AM


Between :42-43: seconds is a 4080 fpm decent. A typical normal descent for a jet aircraft with a professional pilot at the helm.

Between :43-:44 seconds is a 3980 fpm descent. Again.. nothing major for a professional in a jet aircraft. This is even considered "normal". A steep descent sure.. but nothing "abnormal". Abnormal would be in excess of 7000 fpm.

The total fpm descent rate from 42-44 is 4020 fpm. Definitely a good rate of descent, but not abnormal for a professional pilot. Hani, if he did have training as a pilot in Cessnas, would only be used to 1,000 fpm descents. But we already know Hani couldnt control a 172, so i have no idea how he would handle 4000 fpm without hitting the pentagon lawn.

A quote someone was helpful to point out about altimeter lag...

e) Hysteresis: This error is a lag in the altitude indications caused by the elastic properties of the materials used in the aneroids. It occurs when an aircraft initiates a large, rapid altitude change or an abrupt level-off from a rapid climb or descent. It takes a period of time for the aneroids to catch up with the new pressure environment; hence, a lag in indications. This error has been significantly reduced in modern altimeters and is considered negligible at normal rates of descent for jet aircraft.
http://allstar.fiu.edu/aero/PSI.htm

Basically. The above quote is correct. That altimeters do lag. When you abruptly change altitudes. In other words, when you are level and quickly move the stick, you will see a lag in the altimeter momentarily. Then it catches up as your are in the descent. You will also notice most modern altimeters have reduced this lag and that it is negligible in modern jets (mainly due to static port design and computers installed on modern jets).

Another helpful quote from a training site I had found during a quick search (when arguing the lag issue). I used to actually teach this to new students when i instructed full time years ago in Cessna's and Cherokee's.

c. Lag in the altimeter.
(1) Make an abrupt pitch change and point out the momentary lag in the altimeter.
(2) Make small, smooth pitch changes and point out that the altimeter, for practical purposes, has no lag. .
http://www.geocities.com/cfidarren/iplesson1.htm

Now we see in the animation descent that it was deliberate, smooth and not abrupt. The descent rate wasnt abnormal for a modern jet. Therefore... no lag. This may be the reason why Boeing, the NTSB and the FBI do not want to help us decode the additional FDR data to help us confirm that there was most likely no lag. However, the data still needs to be decoded. You would think if this additional data supported the official story, they would be stepping forward to decode it. They arent. Also, if the additional data does lend itself to altimeter lag, then the increased descent rate would have to be explained as it currently conflicts with the DOD video of an object level across the pentagon lawn. Update: The Raw File has been decoded and presents no lag.



Now, if this altimeter is lagging, which we see from the above quotes it shouldnt be, the descent rate will increase from its present data and will be in further conflict with the Dept Of defense video (The "5 Frames Video") showing a level object crossing the pentagon lawn. The above object, which the NTSB says is AA77, its showing a 4000 fpm descent rate for the last two seconds of data in its present form. The video shows it level across the lawn for the very last second (1:26-1:27 in the above video).

If the official impact time was at 09:37:45, that means that AA77 would have had to pull out of a 4000 fpm descent instantaneously and be level across that lawn. IMPOSSIBLE! If this aircraft was too high to hit the light poles (480 feet as noted in the current data provided by the NTSB), it would have more time/altitude available to pull out of this descent and overshoot the pentagon. Leaving a fireball in its wake while quickly exiting the area. Very possible.

If you account for altimeter lag, the descent rate is increased to more than 4000 fpm.

Something is rotten in Denmark.

Now we all know why Boeing and the NTSB do not want to explain nor decode the further data we have. It will only conflict further with the DOD video if they want to use the "lag" excuse. But we know from the quotes its improbable the altimeter showed lag.

Final conclusion, either..

A. altimeter is accurate via the 4 sources of information we have that match and conflicts with the official govt story regarding the light poles and DOD video.

or...

B. The increased descent rate makes it that much more improbable (read: impossible) an object was able to be level across the lawn in the DOD video.
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rob balsamo
post Oct 15 2006, 08:42 AM
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The possible altimeter lag was calculated from a point where there isnt any lag (at normal speed below Vmo and almost level flight) to the end of data. It was ~5500 fpm descent for that period of time. If the altimeter was lagging at the end of data where it shows a 4000 fpm descent rate for the last second in its current state, lagging would mean the descent rate would be in excess of 4000 fpm. Concluding a further conflict with the DoD video which shows something level across the lawn...



Now the argument is that the above video could show a descent even though it shows level with the lawn. And I agree. The gradient for the lawn and that section is roughly 300 fpm descent (43MSL at base of poles - 38 feet at pentagon base = 5 feet x 60 seconds = 300 fpm). Being that the above object is clearly level with that front lawn, it means that object at the MOST has a 300 fpm descent rate. That is in direct conflict with the 4000 fpm descent rate already shown on the FDR. The FDR recording stops just to the right of that camera view. In other words, where the FDR stops, the DoD video begins. They conflict.
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rob balsamo
post Oct 15 2006, 08:42 AM
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FDR stops here, just above the highway in a 4000 fpm descent.


(edit: also note the right bank angle. That also conflicts with the official story that the aircraft needed a left bank angle in order to account for the generator damage. The right bank angle is recorded in the FDR up till reported impact time of :45).





DoD video begins here, just as it crosses the highway level across the lawn with a 300 fpm descent gradient.



They conflict.
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dMz
post Jan 21 2009, 04:36 PM
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QUOTE (johndoeX @ Oct 15 2006, 06:41 AM) *
...
A quote someone was helpful to point out about altimeter lag...

e) Hysteresis: This error is a lag in the altitude indications caused by the elastic properties of the materials used in the aneroids. It occurs when an aircraft initiates a large, rapid altitude change or an abrupt level-off from a rapid climb or descent. It takes a period of time for the aneroids to catch up with the new pressure environment; hence, a lag in indications. This error has been significantly reduced in modern altimeters and is considered negligible at normal rates of descent for jet aircraft.
http://allstar.fiu.edu/aero/PSI.htm

Basically. The above quote is correct. That altimeters do lag. When you abruptly change altitudes. In other words, when you are level and quickly move the stick, you will see a lag in the altimeter momentarily. Then it catches up as your are in the descent. You will also notice most modern altimeters have reduced this lag and that it is negligible in modern jets (mainly due to static port design and computers installed on modern jets)
...

If anyone is interested in really getting technical regarding "pressure lag" in semi-closed systems (out of scope for our purposes here as far as I'm concerned), here is a bit on gas dynamics in tubes (the highly astute reader should already know that "vacuum" is by definition a pressure differential, abstract construct):

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

Gas flow in tubes
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tnemelckram
post Jul 31 2009, 11:58 PM
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Hi All!

Maturin's Post 39 on the Data File Created Before Actual 'Black Box'? thread below mentioned the 29.92 Pressure Altitude adjustment, which made me curious about the subject. I re-watched the discussion of the subject about 39 minutes into Pandora #2, and got even more curious when Rob narrates that the FDR data reflects a pressure altitude correction on the way down but it is not reflected in the animation as it was on the way up by a kickback of the altimeter needle. So I downloaded the FDR data and extracted the tables below. They show Pressure Altitude, Barometric Pressure, and the change in altitude1 from the prior reading for the the 18 seconds up and 17 second down through 18,000 feet. For some context, the PA and BP for the first FDR reading, take off and final FDR reading are also in the tables.

Below are five mixed comments and questions. I know Rob, Maturin et. al. know a lot more about this that I do so please forgive me if I go over old ground. But I don't think this has been discussed before on the Board, so here goes.

1. The first and take off Baro Pressure readings are 30.20. On the way up through 18,000 presumably a real pilot makes a routine and proper adjustment to 29.92 and this appears at 8:27:52. Over the next 12 seconds the Baro Pressure reverts back to 30.21 three times before settling in at 29.92 at 8:27:10. However, on the way down, there is no such fluctuation back to 29.92 in the FDR data. The Baro Pressure moves smoothly from 29.92 at 9:24:14 to a higher range in the 30.00's without ever reverting back to 29.92. Does this inconsistent pattern have any meaning? Shouldn't the data show you about the the same thing in both cases?

2. After the Baro Pressure settles in on the way up, it only fluctuates in a very small range between 29.91 and 29.94 (.03). However, on the way down, it fluctuates between 30.01 and 30.29 (.28 range) before apparently settling in at 30.23, with the final reading also being 30.23. Does this inconsistent behavior have any meaning? Shouldn't the data show you about the the same thing in both cases?

3. It's highly dubious that Hani was sophisticated enough to even know to make the adjustment on the way down, but let's set that aside and assume he was. How would he know what the correct adjustment was? Are these commonly known or easily obtained? How are they distributed to professional pilots? Do they constantly change with the weather? Do they differ from location to location? When the reset is done, is it to the correct setting for the destination airport? How is the correct reset number determined?

4. Taking it a bit further, why would Hani select 30.23? As I understand it IAD's ground elevation is about 500 feet higher than DCA and outdoor Barometric Pressure increases at lower altitudes. If the correct reading at IAD is 30.20 and 29.92 is the default at 18,000 feet, then off the top of my head and using Hillbilly Calculus 30.23 seems to be pretty close for 500 feet lower, although a shade under 30.22 seems to fit even better. The appearance of 30.23 in the data seems almost too perfect to be true.

5. Even if Hani knew how to make the adjustment correctly, why the hell would he even bother, given that where he was purportedly heading safety and following proper procedures would be the least of his concerns? Did he want to leave a nice clean FDR record as a legacy?

TABLES



First
Time PrAlt BarP
08:19:00 00041 30.20

Take Off
Time PrAlt BarP
08:20:20 00083 30.20

Up Through 18,000
Time PrAlt BarP Alt<1
08:27:52 17709 29.91
08:27:53 17747 xxxxx +38
08:27:54 17785 30.21 +38
08:27:55 17823 xxxxx +38
08:27:56 17861 29.91 +38
08:27:57 17899 xxxxx +38
08:27:58 17938 30.21 +39
08:27:59 17976 xxxxx +38
08:28:00 18015 29.91 +39
08:28:01 18056 xxxxx +41
08:28:02 18093 30.21 +37
08:28:03 18132 xxxxx +39
08:28:04 18170 29.91 +38
08:28:05 18210 xxxxx +40
08:28:06 18247 29.94 +37
08:28:07 18288 xxxxx +41
08:28:08 18324 29.91 +36
08:28:09 18364 xxxxx +40
08:28:10 18402 29.92 +38

Down through 18,000
Time PrAlt BarP Alt>1
09:24:10 18285 29.92
09:24:11 18245 xxxxx -40
09:24:12 18205 29.91 -40
09:24:13 18168 xxxxx -37
09:24:14 18126 29.92 -42
09:24:15 18088 xxxxx -38
09:24:16 18049 30.23 -39
09:24:17 18011 xxxxx -38
09:24:18 17972 30.01 -39
09:24:19 17932 xxxxx -40
09:24:20 17895 30.23 -37
09:24:21 17855 xxxxx -40
09:24:22 17815 30.07 -40
09:24:23 17775 xxxxx -40
09:24:24 17734 30.23 -41
09:24:25 17694 xxxxx -40
09:24:26 17653 30.29 -41
09:24:27 17612 xxxxx -41
09:24:28 17569 30.23 -43

Final
Time PrAlt BarP
09:37:44 00173 30.23

________________________
1. The altitude changes show that both the ascent and descent were smooth at around 40 feet per second. I thought they might be helpful as some sort of constant to use in comparing the two events, because they show that the plane's movement was practically identical.

This post has been edited by tnemelckram: Aug 1 2009, 12:27 AM
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rob balsamo
post Aug 1 2009, 12:24 AM
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Hi tn,

I just briefly skimmed your post, but this may help you...

http://pilotsfor911truth.org/forum//index....st&p=992727

Oh, and for question 3 and 4, see top of page at http://pilotsfor911truth.org/pentagon for the METAR. Its an hourly report which includes altimeter setting for the airport that is broadcast on a loop for an hour and is called ATIS (google it for a sample). If they update before the hour is up, it will be noted as a SPECIal (which you can see was updated right after the pentagon attack).

But the interesting thing is, where did "Hani" get 30.24? DCA was reporting 30.22. "Hani" supposedly got a more updated altimeter setting. But as you pointed out, the animation did not reflect this altimeter setting on the descent.

The subtle fluctuations during flight dont really mean anything, someone could have just been playing with the knob checking different pressures.

Also, when analyzing data, you may want to use the original NTSB CSV File instead of RO2 which it looks like you used above. RO2 cannot be argued with any govt agency because we decoded it and there are many anomalies in it. The original NTSB CSV file also has many anomalies, but they decoded it.
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tnemelckram
post Aug 1 2009, 12:49 AM
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Hi Rob!

Thanks for the link to your Post from the Good Ol' Days. Those numbers looked familiar!

EDIT TO ADD: Rob, I may not have read your entire post the first time and missed what you wrote below the link or or maybe you edited it and the edit crossed with this original post.

But I think this is something different. Your linked Post seemed to focus on the discrepancies between the FDR data and the Animation, comparing the two. What I'm suggesting is that the FDR data is internally inconsistent because you would expect the FDR data to show the same pattern both going up and going down through 18K (it's essentially the same event, although reversed). EDIT TO ADD: Thanks - your comment in your above Post about the fluctuations being insignificant addressed this!
SECOND EDIT: Well maybe it wasn't intended to address it completely. You only mentioned "subtle fluctuations" during flight as being insignificant. Maybe these aren't "subtle" and inconsistencies aren't the same thing as "fluctuations".

When you or anyone else gets a chance, it would be helpful to know the things about Baro Pressure adjustments in questions 3 and 4. The apparent ultimate adjustment to 30.23 looks spookily correct. Even if Hani knew that the adjustment was required, how would he have this additional information to do it correctly? EDIT TO ADD - Thanks for the lead in your above Post about METAR. I'm going to look at it and it should be helpful. I have a hard time believing that Hani would be able to make this adjustment, and that's after having an even harder time believing that he would be inclined to do it in the first place, given the alleged circumstances.

This post has been edited by tnemelckram: Aug 1 2009, 01:10 AM
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rob balsamo
post Aug 1 2009, 12:54 AM
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QUOTE (tnemelckram @ Aug 1 2009, 01:49 AM) *
When you or anyone else gets a chance, it would be helpful to know the things about Baro Pressure adjustments in questions 3 and 4. The apparent ultimate adjustment to 30.23 looks spookily correct. Even if Hani knew that the adjustment was required, how would he have this additional information to do it correctly?


See my edited post above... smile.gif
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tnemelckram
post Aug 1 2009, 05:26 AM
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Hi Rob!

I found the following Article dated 2000 about delivering METARS to the cockpit via a heads up display. I think it is indicative of the state of the art on 0-11-2001. It seemed to be in more of a commercial aviation context as opposed to a lot of the links in my search which seemed obsessed with selling what are now much fancier computer-driven products to private pilots for use on laptops.

http://www.icao.int/anb/SG/METLINKSG/meeti...NK5/wp/ip18.pdf

QUOTE
.2.2 Currently this information is available in Repetitive Sequential (Automatically repeating and
broadcasting the information in the following products ATIS, ASOS, and AWOS) or Head-Down formats
(METAR); information can also be relatively dated when received by the crew. The data included in
automated reports and METARS are useful; however a real-time presentation of the more dynamic/varying weather phenomena is generally the most relevant for a given flight operation.

2.3 Repetitive Sequential access to information is cumbersome because the volume of immediately applicable information is included along with information that is not immediately applicable or
important (noise). The flight crew may be interested in the current wind vector, but may have to listen to[extraneous] information while awaiting the recording to come back to the current wind vector.

2.4 Head-down access to information can be cumbersome because the information is displayed
in a location, which is relatively distant from other flight-data presentation. This is not an ideal situation as it distracts the flight crew from flight data and the additional head-movement could induce spatial
disorientation in severe circumstances. In the case of data-linked METAR, the information can be dated


So I guess "Hani could have gotten" the Baro Pressure by (1) knowing how to tune to the right DCA radio frequency; or (2) knowing how to adjust some type of display located somewhere in or on the mass of instrumentation so that it would show DCA. If successful, then he has to be able to read the METARS format.

SO I'm thinking that "Hani" slips behind the controls of an aircraft that a proper pilot has all set up to fly West across the country. Burlingame was concerned about what lay ahead of him and certainly would not have either one of the radios or the heads down METARS display set to receive from DCA, which was behind him and not associated with his flight. Hani is turning the plane around to go East. He or one of his cohorts would have to know DCA's METARS frequency (now 132.65 according to AirNav) and how to change the tuning of the radio to that frequency. Or he would have to know how to adjust the heads down display apparatus to receive DCA.

In the FDR data, I saw various radio frequencies in the VOR (MOD) and VOR spaces. My research suggests that these are navigational beacons and would not transmit METARS data (is this correct?). I don't think they will shed any light on the matter of how "Hani" got 30.23. The only numbers that look like radio frequencies in all of the data seem to appear only as VOR data.

VHF LEFT KEYING was interesting but all that does is show whether the Pilot had the transmit button pressed and has nothing to do with what receiving frequency the radio was on (I think). There doesn't appear to be any way to determine what they might have been listening to from the FDR data.

WPT F/O, WXR DATA CAPT, and WXR DATA F/O all look like they might have something to do with the head down METARS display. They show "Select" or "Not Select" which I guess means "on" or "off".
This FDR data doesn't show where the data was coming from. However, since east-flying "Hani" would need different data that west-flying Burlingame, there should be a "Select" reading sometime after 12:50 when the plane was hijacked if he received the DCA METARS data through the heads down display. If someone who knows more than me thinks that this is likely to be fruitful, I'll plow through the data after 12:50 looking for a "Select" entry in one of these three items of FDR data. That way we can rule out one way for him to get the 30.23 adjustment.

That's as far as it goes for now. Rob's or anyone else's input would be appreciated.

PS. I still swear I smell something in the "internal inconsistencies" in the Baro Pressure data described in the above Posts. I suppose a lot depends on whether the FDR Baro Pressure data reflects just the reading shown on the instrument, or whether it reflects some measurement done by the device independent of whatever number the pilot sets it to (perhaps for calibration purposes each time it is changed). Are there any more-qualified noses that smell something stinky there?

This post has been edited by tnemelckram: Aug 1 2009, 05:40 AM
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