New FDR Decode

reply to post by 767doctor


I don't know if ,"why not right" is enough of a reason to make me feel all
warm and fuzzy inside.

Just the thought of Hani obtaining the local pressure values...setting one
altimeter (for no apparent reason) is a tough story to swallow, 'as is'.

Now add: stretching across to fiddle with a totally irrelevant knob while
flying a 757 for the first time.

Weird.

It’s kinda like me reaching down to the passenger side floor mat of my car
while driving 120 MPH on the freeway to fix a wrinkle just before I plan to
slam into a wall.

reply to post by turbofan


Well, ingrained habit?

Just the thought of Hani obtaining the local pressure values...

As already pointed out, not difficult for any pilot, even a student pilot would know where to look for hte ATIS frequency.(Ooops...Caps Lock was on, just noticed).

...setting one altimeter (for no apparent reason) is a tough story to swallow, 'as is'.

Again, habit?

And, lacking the CVR we just will probably never know IF he had someone else up there with him...there were five total, the other three could have kept the cabin secured.

Now add: stretching across to fiddle with a totally irrelevant knob while flying a 757 for the first time.

Don't fall for that trap!

Simulator practice, perhaps many hours...they had nearly unlimited funds.

And, on autopilot. Setting the baro knob is easy as it gets...you grasp, turn and watch the settings change...


[edit on 28 December 2009 by weedwhacker]

Originally posted by 767doctorWell, in the interest of transparency, we can only say that "There is no EICAS connection for FLT_DECK_DOOR" on the 757 fleets we have access to. For me, that would be Delta, TWA/American, Northwest, British Airways, ATA, Omni Air International and Ryan International - about 300 airplanes in all.

Fair enough!

The only thing we can say is that its not a stock feature on the 757; its a customer option. That is, the customer needs to pay extra for that feature, or install it themselves. I can say that none of the 300 ships, which I have manual access to, has this feature installed.

Coupled with the non-toggling data...it makes for a very weak theory.

there is still a sealed diaphragm that looks for changes to its resonant frequency with changes in ambient pressure. The change in ambient pressure still has to completely fill the sealed area on one side of the diapraghm(much like a bellows needs to have its sealed "test area" completely filled before the motion is accurate)before its frequency changes. Based on that, I'd say there is still a chance for lag, but not as much as traditional systems. Maybe you'd only see the lag under very high rate of climbs/descent, but it's there.

I'm going to disagree for a few reasons:

Based on the sensor used in my lab at work, I can say the "reaction"
time of the pressure change to the moment our software interprets a
change is within milliseconds.

We can monitor a change in pressure as much as one full atmosphere
when a vacuum seal breaks on the chamber in less than a quarter of a
second. This triggers a relay to shut down power to the RF amplifiers
in order to prevent damage to a flight device.

When I go back to work next week, I'll take a snap shot of the sensor
and also get a part number. We can look up the specs and find the
transient response, propogation delays, etc.

Another application of pressure sensing is in your car. I own two types of
software and acquistion systems that can monitor engine performance
and read input/output sensors around the engine.

By the time I tap the accelerator pedal, I can see the fuel injectors adjusting
their pulse width to add/reduce fuel on the computer screen.

In other words, the change is happening as quick as my eye can see an
update in the software. Keep in mind, the pressure in the motor is changing
much quicker and more abruptly than a descent in an aircraft. The
pressure is sensed, relayed to the car's computer...the computer sends
out instructions to adjust fuel ratio...the oxygen sensors measure this
change...send the data back to the computer...my analyzing software
reads all of this and updates me within a blink of an eye.

Those are just two real world examples of pressure sensors reacting
near instantaneously to provide information. Based on these inexpensive,
relatively incomplex systems, I cannot agree to the 'lag theory' with
respect to the sensor itself.

I believe the delay that you are viewing is intergal to the calibratoin system
in the form of latency (perhaps). This is not the same as the sensor
reacting to the pressure change...but rather the signal chain from your
DUT to the output screen of your test bench.

If you're willing to work with me, we can look up manufacturer data and
pull up the performance specs of these devices. I may even be able to
wire up a small circuit at home to illustrate how fast the pressure is sensed

IE: Connect a pressure sensor to a balloon and pop it.



[edit on 28-12-2009 by turbofan]

reply to post by Lillydale


there are many who describe the actual impact. You may continue to blind yourself to these details, But you will gain no traction for your conspiracy claims.l Is that clear?

Steve Anderson Shortly after watching the second tragedy, I heard jet engines pass our building, which, being so close to the airport is very common. But I thought the airport was closed. I figured it was a plane coming in for landing. A few moments later, as I was looking down at my desk, the plane caught my eye. It didn't register at first. I thought to myself that I couldn't believe the pilot was flying so low. Then it dawned on me what was about to happen. I watched in horror as the plane flew at treetop level, banked slightly to the left, drug it's wing along the ground and slammed into the west wall of the Pentagon exploding into a giant orange fireball. Then black smoke. Then white smoke.

Deb Anlauf Anlauf was watching TV coverage of the Trade Center burning shortly before 9:30 a.m. when she decided to return to her 14th-floor room from another part of the hotel. Once in her room, she heard a "loud roar" and looked out the window to see what was going on. "Suddenly I saw this plane right outside my window," Anlauf said during a telephone interview from her hotel room this morning. "You felt like you could touch it; it was that close. It was just incredible. "Then it shot straight across from where we are and flew right into the Pentagon. It was just this huge fireball that crashed into the wall (of the Pentagon). When it hit, the whole hotel shook."

Gary Bauer “I was in a massive traffic jam, hadn’t moved more than a hundred yards in twenty minutes. My office called to tell me about the first plane in New York, the reaction was ‘horrible accident.’ And then they called about the second plane, and clearly that meant something much worse was going on. It was only then that I really noticed where I was in that traffic jam. I was going past the Pentagon, really inching a yard or so every couple of minutes. I had just passed the closest place the Pentagon is to the exit on 395 . . . when all of a sudden I heard the roar of a jet engine. I looked at the woman sitting in the car next to me. She had this startled look on her face. We were all thinking the same thing. We looked out the front of our windows to try to see the plane, and it wasn’t until a few seconds later that we realized the jet was coming up behind us on that major highway. And it veered to the right into the Pentagon. The blast literally rocked all of our cars. It was an incredible moment.

Sean Boger "I just looked up and I saw the big nose and the wings of the aircraft coming right at us and I just watched it hit the building. It exploded. I fell to the ground and covered my head. I could actually hear the metal going through the building."

Donald R. Bouchoux "At 9:40 a.m. I was driving down Washington Boulevard (Route 27) along the side of the Pentagon when the aircraft crossed about 200 yards in front of me and impacted the side of the building. There was an enormous fireball, followed about two seconds later by debris raining down. The car moved about a foot to the right when the shock wave hit. I had what must have been an emergency oxygen bottle from the airplane go flying down across the front of my Explorer and then a second piece of jagged metal come down on the right side of the car."

I have run past my character count. But that just a sampling of my post elsewhere in response to a no planer denying there were witnesses to the actual impact



[edit on 31-12-2009 by A W Smith]

Originally posted by A W Smith

And all that drivel has exactly what to do with the FDR decode ?

reply to post by JFrickenK


JFK....what is the MANTRA of the "no planers" like CIT, P4T, LCF, etc, etc, etc???

Well, in one nutshell, they keep flapping on about how the FDR "Can't be trusted" to be accurate data, despite vast amounts of corroborating evidence to suggest American flight 77, not limited to, but including:

This new FDR decode;

And the re-iteration, as A W Smith posted, of just a FEW of the valid eyewitnesses;

And the damage pattern, consistent with a Boeing 757;

And the debris and fragments recovered, consistent with a Boeing 757;

And.....


Why bother going on? The gravy train is coming to a stop, for the CT sites, hopefully. Well, at least and until you attract a whole new crop of gullibles who will no doubt be flabbergasted by the snake oil and trinkets, and gladly pony up some bucks or pesos or Euros or sheckles to buy into the hoo-haa....

Originally posted by weedwhacker

< snip more non relivant drivel >

And that reply has exactly what to do with the FDR decode ?

And since everyone else is I will also go off topic to say that I believe the 8 or so witnesses who have stated on camera that the plane approached from the north side of the Citgo...

I have yet to see just one who will go on camera supporting the SOC approach, and that DOES present a HUGE problem for you official story supporters.

Frankly I don't GAFF if it flew over or not...
THAT is irrelevant as MY government HAS lied to ME with it's lightpole story.

WTF else have they lied about ?
( I can think of several things which they lied about to the general public whilst I was active in the military )

reply to post by JFrickenK

And that reply has exactly what to do with the FDR decode ?

This, ladies and gents, is the very perfect example of a web tactic called "trolling".


But, to attempt to (once more) for those poor innocents who've only now tuned in, and may think that JFK is actually making some sort of valid point (he's not).........


The new FDR decode completely DESTROYS the 'north of citgo' theory once and for all. It completely DESTROYS the 'no-planers' and their magical mystery tour fantasy of the 'overfly' with explosions and lighting effects courtesy of a Hollywood SFX team. THAT is the relevant, non-snippable fact that makes it pretty clear to just about everyone else, except for those who are married to their fantasy for some other reason, as I've suggested already.

And weedhacker throws all the professionals who witnessed it go NOC under the bus.

Why am I not surprised ?



Mod Note: One Line and Short Posts – Please Review This Link.
Mod Note: Please Stay on Topic

[edit on Mon Jan 4 2010 by DontTreadOnMe]

Originally posted by JFrickenK
And weedhacker throws all the professionals who witnessed it go NOC under the bus.

Why am I not surprised ?

Call to false authority noted.

Aircraft crash investigators witnessed the north of citgo path? Or are you talking about the minority employees who professionally mow the grass at Arlington? Or the guy in uniform spending time actually talking to his friocken K9 as the plane flew south of citgo? Or the other guy in uniform who had his back to the annex and could only witness from his viewpoint from inside a motor vehicle? What fricken professionals are you speaking of JfrickenK that can disqualify the scores of witnesses who contradict their testimony and who actually saw the impact? And what prey tell has your comment have to do with flight data decode that slam dunks your conspiracy fantasy?

[edit on 31-12-2009 by A W Smith]

Originally posted by A W Smith

Originally posted by JFrickenK
And weedhacker throws all the professionals who witnessed it go NOC under the bus.

Why am I not surprised ?

Or are you talking about the minority employees who professionally mow < Snip >

Your racially motivated stance is noted.

Onto my ignore list you go.


Mod Note: One Line and Short Posts – Please Review This Link.
Mod Note: Please Stay on Topic

[edit on Mon Jan 4 2010 by DontTreadOnMe]

Originally posted by JFrickenK

Originally posted by A W Smith

Originally posted by JFrickenK
And weedhacker throws all the professionals who witnessed it go NOC under the bus.

Why am I not surprised ?

Or are you talking about the minority employees who professionally mow < Snip >

Your racially motivated stance is noted.

Onto my ignore list you go.

Well hell you ignore everything else that's inconvenient to your fantasy. Why am i not surprised by the actions of a small group of conspiracy hacks who demonize a minority taxi driver?


Mod Note: One Line and Short Posts – Please Review This Link.
Mod Note: Please Stay on Topic

[edit on Mon Jan 4 2010 by DontTreadOnMe]

I'll revisit the altimeter lag argument shortly, if anything just to tie up the loose ends from this discussion. I believe lag played a large part in the error of the pressure altitude in the final moments, but showing "proof positive" that lag caused the error is unnecessary. Here's why...

A short dialog with Warren Stutt, in reference to PfT's pressure altitude argument, got me thinking along some different lines. I suppose I knew all along that the 757's Air Data Computing/Pitot-Static System wasn't designed for such a flight profile as AA77s final "attack run", but I didn't think I could demonstrate such without information not currently at my disposal. A question from Warren about a parameter - Total Pressure(which I'll refer to as Pt)- got me digging in the manual about pressure limits. Long story short, I found a few things that should bury the "pressure altitude reads too high" issue for any rational mind.

I'll show the following:

- AA77 was travelling at 488 knots True Air Speed(TAS) at the end of data, some 141 knots above the 757's max operating speed(VMO). This obviously means that AA77 was operating well beyond the 757 flight envelope; meaning that the Air Data system was never tested, calibrated, or certified for such extreme conditions.

- The Total Pressure(Pt) at the end of data exceeded 42 in/Hg, resulting in a differential pressure of over 12 in/Hg between Total Pressure(Pt) and Static Pressure(Ps) This is important because, as I'll show, the 757 Maintenance Manual states that differential pressures over 10 in/Hg can cause damage to the Pitot-Static System. Enough said.

- The Air Data Computer is never tested for anything approaching the pressures that AA77 experienced approaching impact. As I'll show, pitot and static(speed and altitude) pressures are tested in pairs(this is because the Air Data Computer is calibrated to condition raw static/altitude data with different airspeeds, angle of attack, and air temperatures) which check only low speed/low altitude and progress in a linear fashion to high speed/ high altitude. High speed/low altitude profiles are not tested, and we can assume that the ADC is not calibrated to be accurate in such a regime, especially given how far beyond the flight envelope AA77 was.

- Finally, and probably most importantly: The 'Air Data Accuracy Test' allowable errors pertain to test conditions only, and don't include error from "..the aerodynamic effects of flight". Rob Balsamo will try to have you believe that the error pertains to flight conditions. I'll show that it doesn't.


757 Flight Envelope/VMO


Reference: 757 Air Data Accuracy Test

The far right hand column is the computed VMO(or Velocity, Maximum Operating) based on input pressures which simulate a range of airspeeds and altitudes. You'll notice that from 0' up to 18,000', the 757's VMO is 347 knots. The speed at the end if data is 488 knots, some 141 knots over VMO. That's not barely past the envelope; its into uncharted territory. No 757 has flown that far beyond VMO and lived to tell the story.

Why is any of this trivial information important? Because Air Data Computing Systems are only designed, tested, and calibrated for conditions within the vehicles performance envelope and perhaps even slightly beyond.



Differential Pressure Beyond Damage Threshold.

Reference:
757 Air Data Accuracy Test(from Boeing's Maintenance Manual.)
FDR Decode - Airspeed and Total Pressure(Pt) Fields at End Of Data
Total Pressure Conversion

Note the large bolded text at the beginning of the procedure which states:

"MAKE SURE THE DIFFERENCE BETWEEN TOTAL PRESSURE AND STATIC PRESSURE DOES NOT EXCEED 10 IN/HG....THIS WILL PREVENT DAMAGE TO THE PITOT-STATIC SYSTEM"

What that means is you cannot supply too high of an airspeed for a given altitude, or damage can occur. I've actually damaged and Air Data Computer once by not heeding a similar warning. The system is designed for only a certain range of pressures and up to a delta of 10 in/Hg between altitude and airspeed. This was grossly exceeded in the final moments of AA77's existence, as you will see.

Note the FDR Decode link above shows that Total Pressure(Pt) as 1442 mB's at the end of data. The Static Pressure(Ps) parameter is unavailable; however its not needed as we know that a pressure altitude of -99' MSL, AA77's altitude at end of data, is equivalent to 30.030 in/Hg. Since we have a mix of units, and we are looking for both units to be in in/Hg - we have to convert the 1442mB. Note the Total Pressure Conversion above and we'll see that 1442 mB is equal to 42.58 in/Hg. So we have:

a Total Pressure of: 42.58 in/Hg
a Static Pressure of: 30.03 in/Hg

..giving us a difference in pressure of 12.55 in/Hg. What did that note say again?

"MAKE SURE THE DIFFERENCE BETWEEN TOTAL PRESSURE AND STATIC PRESSURE DOES NOT EXCEED 10 IN/HG....THIS WILL PREVENT DAMAGE TO THE PITOT-STATIC SYSTEM"

There ya go, moving on...






[edit on 1-1-2010 by 767doctor]

Air Data Computer Test Range


Reference:
757 Air Data Accuracy Test

Note the Maintenance Manual figure above. With a given set of test pressures(at left), you'll see the output altitudes and speeds with an accuracy figure and "delta" figure. The thing that's important here is the range that is being checked, note that the only airspeed checked with 0' altitude is 150 kts. The full range goes like this:

0' 150 kts
10,000' 200 kts
20,000' 300 kts
30,000' Mach 0.75
35,000' Mach 0.80
40,000' Mach 0.85

This is the calibration range that is tested for accuracy. Note that there is no 0' 490 kts test point, or anything remotely close to it. As I mentioned, the Air Data Computer is calibrated over the normal flight envelope, and this test shows that there are no tests for any speed/altitude combination outside that flight envelope. Actually, it even shows that only a relatively small range within the flight envelope is checked for accuracy - that being only the typical airspeeds for the given altitude.

The other thing to notice, again, is the difference between Total and Static Pressures(these are at left). You can see that over the test range, the maximum difference is about 4.8 in/Hg. Recall what AA77 was experiencing in the final moments; 12.55 with 10.0 being the damage threshold.



Air Data Computer Accuracy


Reference:
757 Air Data Accuracy Test


I'll keep this point short. Just note the highlighted portion at the bottom..

"..the aerodynamics of flight do not contribute to the tolerance allowance"

So, at 0' and 150 kts, a tolerance under test conditions of +/- 25' and +/- 2.0 kts is allowed. That is, to re-iterate, under perfect test conditions - not subject to aerodynamic disturbances. Rob will have you believe that the tolerance is for flight conditions, it's not. This renders any argument to the effect of "the accuracy for an altimeter at 0' MSL is +/-25', so AA77 is still (x)' too high". completely void, particularly when you take into account the other points made above.






I hope some of you found this to be enlightening. Most aviation experts here already kinda know most of this, but I thought showing it would be a good idea since these claims keep persisting. If anyone has any specific problems or corrections to the above, I'll gladly discuss them.

Tino:

The meta-argument of whether or not the altimeter was slightly lagging behind is sort of moot, but I'll dig up some stuff on the ADC's Pt and Ps transducers for you. I've looked quickly through the 'Functional Test'(bench test) for those sensors and there isn't a test for lag, just accuracy tests, leak rate tests, and latency tests for the output ARINC data words. IIRC, these were something like 250,000-1,000,000 nanoseconds. But that's obviously not related to the lag I was talking about. The leak rate tests could be something like what we're looking for, but I don't think we'll find anything too concrete...it's worth a look though.



ETA: Happy New Year everyone!



[edit on 1-1-2010 by 767doctor]

Awesome Jay, I'd be very interested in learning more about the ADC
with respect to the altimeter measurement.

I'm happy to see that you're not pushing the lag argument as per
"reaction time" of the sensor. No matter what side of the debate
you support, it's important to develop a sound theory based on facts
to help explain your position.

I'm much more impressed with your previous posts about design limitations
of the ADC, than buying into any sort of "lag" in the system.

The nano-second propogation is about right for response time of the
pressure sensor. I'll see if any sort of specification sheet is available
to confirm these numbers next week once I get part numbers.

Here's a bit more info that I've been digging up about modern solid
state altimeters:

Design of Frequency Modulated Altimeters

www.freepatentsonline.com...

link




[mod edit: fixed long link skewing page]

[edit on 2-1-2010 by 12m8keall2c]

 



I had printed out the part numbers for the Ps and Pt transducers for the Honeywell 4040800 ADC as well as the spec sheets, and test procedures but I left them in my tool box - that's where I got the information in my last paragraph above. In the interest of transparency, I'll bring them home Monday evening and post them here.

Like I said, there's nothing that really applies to lag in the bench test setup. But the leak rate test would give a good idea that there is an acceptable leak rate, which would lead to lag, but it would take a lot of number crunching to convert the leak rate into (x) seconds of lag. IIRC the latency test covers the "electronic lag" from the output of the transducers to ARINC data word encoding. It doesn't cover the process of pressure conversion within the transducers.

Like you said, we should base our theories on the actual facts. There are certain things I can show here, as I did with the posts above, using technical data. But there are other things I can't show here which relate to my experience in this field.....like lag.

I obviously can't show you here, but I have seen lag in B737s, 757s, 767s, MD11s, etc when doing pitot-static checks. A technician doing such a check can actually see the lag that pilots can't see. We have a test set which we physically connect to the aircrafts pitot-static system using pitot probe and static adaptors. We supply test pressure to simulate the plane in flight. As a tester, I sit in the cockpit with the remote(seen in the link above) and when I change altitudes, the remote shows the simulated pressure altitude in 5' resolution, as well as the target altitude and rate of climb/descent. Whenever passing an altitude, you can notice the remote altitude(which represents the ambient atmosphere) is always slightly ahead of the Capts and F/Os altimeters at high rates of change...say 5000 fpm or more(I use 5000 fpm during tests, so the task doesn't take all day). Once the target altitude approaches, the rate slows down and the lag becomes unnoticeable or eliminated completely.

Perhaps this lag is artificial, possibly the time it takes the pressure/vacuum source in the test set to reach the pitot/static ports as the hose lengths for the test set can be 20' or more. But then again, why wouldn't there also be "artificial lag" at lower rates of climb/descents? I really don't know, but as I said above, this is really just "gee whiz" info now as we have a more concrete source for the error.

I, too, appreciate your willingness to look at the larger picture, Tino. Sometimes it's easy to get "tunnel vision" when looking into some claims and you lose perspective of how said claim fits into the larger picture. You probably know as much from troubleshooting your car or electronics. Sometimes we get an idea, either based on instinct or previous experience, about what a problem will be and often be lead astray. I thought pneumatic lag had alot to do with AA77's altitude error, but now I'm not too sure it isnt a variety of other factors.

[edit on 2-1-2010 by 767doctor]





..............................................................................
[edit: removed unnecessary quote of entire previous post]
Quoting - Please review this link

[edit on 2-1-2010 by 12m8keall2c]

Thanks Jay, I'm all for, "looking at the big picture" and checking out new
theories.

If we were to look back in the data, where would we expect to see the
ADC begin to produce errors in PA? Near Vmo?

Can we use any altitude from about 4000' AGL to compare with RAD ALT,
along with accelerometer trends and landscape to check whether the ADC
was in error?

At some point there will be an obvious "bump" in the altitude readings
when the pitot-static system pukes due to overspeed, correct?

P.S. Check your U2U

Originally posted by A W Smith
reply to post by Lillydale

 

there are many who describe the actual impact. You may continue to blind yourself to these details, But you will gain no traction for your conspiracy claims.l Is that clear?

Many? No. Perhaps you should go back and try reading what I actually said again. Why is this so hard for people to do around here? My last post specifically refers to another post with a list of 3 witnesses. These 3 witnesses were held up as EYEwitnesses to the crash. I pointed out that 0 out of those 3 actually saw the impact. If you want to refute what I say, try reading what I said first.

I have run past my character count. But that just a sampling of my post elsewhere in response to a no planer denying there were witnesses to the actual impact

Hmmmm...not a no planer and have already acknowledged there were a few people that saw something impact. We have it on video. I get that part. My post was specific and if reading the entire thing and maybe the post it replied to in order to understand that might be a lot for you to handle but I suggest you give it a try before attempting to correct me again. Make sure you are actually correcting something someone said next time is all.



Mod Note: Please Stay on Topic

MOD NOTE: ATTENTION ALL 9/11 POSTERS

[edit on Mon Jan 4 2010 by DontTreadOnMe]

Mod note: No really. Stay on topic or don't post. -- Majic



[edit on 1/5/2010 by Majic]

I fervently hope that the work offered by Warren Stutt, a researcher who has no other agenda and is beholden to no one but himself, will finally put the lid on this issue.

Too much bad information has been promoted by certain self-serving "factions" on the InterWebs, based on a particularly BAD interpretation of the American Airlines flight 77 FDR data that was "decoded" and skewed in a way to support these sites' (previously mentioned) points of view, to further their agendas.

Thank goodness Mr. Stutt took the time and made the effort to clear the air on this issue.

It is a shame, however, that many will NOT accept reality, no matter that it is presented as squarely and plainly as possible. AND is corroborated by actual experts' contribution, not jsut a few bloggers on the 'net.