New FDR Decode

reply to post by R_Mackey


Mackey, I have been wrong about a lot of things and have no problem admiting it. I remember when I started looking into this stuff I triangulated off the wrong tree on the Doubletree video and identified a low altitude helicopter (actually a smudge flying past on the video) as a plane. The math was right, the tree was wrong. Took me about a week to figure that one out. Hey, I married my wife and that turned out to be a big mistake.

Forgive me, but I don't take internet forums too seriously, nor do I consider them a serious venue. This is the only one I post on and that is very infrequently. When I do, I don't treat the subject matter too seriously because I find that most people just want to argue. I sit here stunned that a professed engineer would actually assert that a pressure altimeter measures altitude. No it does not. It measures air pressure and infers from it altitude. If the plane is sitting at the gate and a cold front moves through, it will measure the pressure change and infer a change in altitude unless it is told that the barometric pressure changed. It has no way of knowing otherwise.

I'm also stunned that you would not insist on a standard reference system for discussion of measurements (ENG 101). If the end topic is the terminal event at the Pentagon, where everyone is using the USGS database, then all measurements related to the discussion should be made in reference to the same standard. I guess the USGS could be the wrong standard to use, but it is the only one common to both.

I really am not concerned with what you think. I had these discussions over PA with Cpt Bob years ago and although he won't admit it, he knows I am quite familiar with the topic

Originally posted by turbofan



Is this "the" R_Mackey?

Much respect for doing the right thing if so.

No, it isn't. Ryan has been asked on a few occasions to join and has refused. If you read Mackey's posts on JREF, you would know this isn't him.

More likely Rob Balsomo or one of his friends.

reply to post by ImAPepper


No Pepper, this is Mackey for sure. He is just mad at me cause I took issue with him on measurement error once and is getting payback. But that is okay though, I'm starting to understand why they had a tough time getting the Ares rocket off the ground this week.

posted by turbofan

Is this "the" R_Mackey?

Much respect for doing the right thing if so.

posted by ImAPepper

No, it isn't. Ryan has been asked on a few occasions to join and has refused. If you read Mackey's posts on JREF, you would know this isn't him.

More likely Rob Balsomo or one of his friends.

posted by 911files
reply to post by ImAPepper

 

No Pepper, this is Mackey for sure. He is just mad at me cause I took issue with him on measurement error once and is getting payback. But that is okay though, I'm starting to understand why they had a tough time getting the Ares rocket off the ground this week.

Gee Dr Pepper; a busy little beaver making false accusations again? It seems that the NASA rocket scientist joined up specifically on October 30 2009 to correct the incessant errors JREF disinformation specialists 911files and Reheat and weedwhacker have been spitting out. Why would Rob Balsamo or one of his friends want to be a NASA rocket scientist?

Can you point out where in the last few pages that Ryan Mackey is in error? John Farmer is infamous for his mathematical errors of epic proportions.

[atsimg]http://files.abovetopsecret.com/images/member/63b7387179af.jpg[/atsimg]

Originally posted by ImAPepper

Originally posted by turbofan
Is this "the" R_Mackey?
Much respect for doing the right thing if so.

No, it isn't. Ryan has been asked on a few occasions to join and has refused. If you read Mackey's posts on JREF, you would know this isn't him.

More likely Rob Balsomo or one of his friends.

Really. More playground fun from the PfT club! Why am I not surprised. Sure reads like Cap/t Bob.

Preston, you guys crack me up. I guess since the guys at JREF caught this and are talking about it, might as well let the proverbial 'cat out of the bag'.

No it not Mackey but I was going to play along for awhile for the fun of it with the real Mackey's consent, but I guess we'll just have to say hello to Capt'n Bob, aka R_Mackey. Good morning Capt'n

reply to post by turbofan


Funny, stars for this? Nevertheless,

Impact sensing would include accelerometers no doubt.

Of course. BUT, where are they located? And, what are their actual functions? (Hint...Laser-ring gyros).

I read something about Bleed Air Ducts, however I'd have to look into that further.

Feel free to waste your time, it's yours to waste. If you do not know what Bleed Air is, then I won't bother to help you here. Come back and tell us how many accelerometers are mounted in the Pneumatic System, ok?

Engine smoke would be picked up by Air/Fuel ratio sensors, fuel and/or oil pressure sensors, turbine RPM sensors ...ummm...what else...

Yes, I mentioned that...N1, N2 (what you called "turbine RPM sensors). I mentioned oil pressure. Air/Fuel ratio sensors?!? (It's not a piston engine...) Where, in the FCU? I think what you're going for, here, is the F/F (fuel flow) measurements.

Originally posted by SPreston
John Farmer is infamous for his mathematical errors of epic proportions.

Actually Presto, it is P4T and crowd who is infamous for not being able to comprehend Newtonian physics and vector mechanics (both math based) and instead use graphics software to estimate 11+g pull-ups.

posted by 911files
Preston, you guys crack me up. I guess since the guys at JREF caught this and are talking about it, might as well let the proverbial 'cat out of the bag'.

No it not Mackey but I was going to play along for awhile for the fun of it with the real Mackey's consent

Ryan Mackey is indeed a famous personage, in addition to being a NASA rocket scientist spouting disinformation from the Forum of Magicians and Illusion.

The Short Reign of Ryan Mackey

More than likely it was one of your own JREFers attempting to setup another pathetic strawman argument to tear down. But keep up the good work as the numbers of awakened Americans and world citizens demanding a real investigation into 9-11 are growing. Thanks for the help guys, and thank you especially for sending jthomas to sabotage your precious 9-11 OFFICIAL STORY fairy tale.

[atsimg]http://files.abovetopsecret.com/images/member/63b7387179af.jpg[/atsimg]


[edit on 10/30/09 by SPreston]

reply to post by SPreston

...the incessant errors JREF disinformation specialists 911files and Reheat and weedwhacker have been spitting out.

I know nothing of Mr (or Ms) "reheat"...(other than when I see the screenname I think of after-burners, which I supposed is the intent...lost on all but other pilots, though...)

So, not sure if "reheat" has been or currently is on "JREF". I certainly have never posted there, only learned of the good stuff on the site from reading about it here.


Now, AS TO the FDR and what is (and isn't) in it, per the P4T, et al, please be so kind as to point out where the "reheat", and I have been "spitting out" any "incessant errors". We (each of us) can only speak from experience..."reheat"'s is, admittedly, NOT in the airplanes involved on 9/11, but from a military pilot's standpoint. I, on the other hand, DO have several thousands of hours in the B757/767. So, my information is, to the best of my writing abilities to convey, based on my experience and understanding.

I struggle to write in a way that isn't too technical (I fail there, I know...and eyeballs roll up into their sockets) but there is a point when, if you "dumb it down" too much for laypeople it may lose clarity...so it's a fine line.

There are only so many sources available on the 'Net to illustrate my points, so I have to fill in the gaps with verbiage. Again, not to "show off", but to demonstrate that I have knowledge that is not found by 'googling'...

Too many times there are amateurish misconceptions about matters of aviation uttered here on ATS, a kind of 'folk lore' urban legend thing --- I try to clear those up with facts. And, sometimes inadequate analogies, but usualy someone comes along to build on that, and help to clear up what I'd missed.

SO, I present the challenge to find any intentional "disinfo" on my part (I cannot nor will I speak for "reheat") when it comes to what I know about the SSFDR in particular (and, I've learned a lot...much more than we were ever required to know, just to operate the airplanes) and aviation and the B757/767 in general.

As far as I know, I have no clue who weedwacker is beyond his posts here. Reheat and Mackey I do know from JREF.

As even Reheat and Mackey can attest, I have serious issues with some aspects of the 'official story'. Reasonable people can however disagree and still respect one another's abilities and point-of-view. Darn, I even hang out with Mark Gaffney and we disagree on a lot of stuff, but he is an honest broker who sincerely wants to understand the events of that day.

However, this episode with the Mackey impersonator reveals the problem I have with P4T. They, nor their cohorts at CIT can be considered even remotely close to being 'honest brokers'. Deception and disinformation is their game, and they make government agencies look like truth fairies.

Speaking of mistakes, I wonder why those "verified by the FAA" cult have not corrected "the technologist's" mistake and misleading statements about baro altimeter accuracy. The 20' accuracy that Turbo has been touting is a manufacturer's tolerance on the instrument itself which does not include the piping and other installation issue such as, placement and performance of the static ports. Consequently, it is misleading and WRONG. It is obviously aimed to mislead those who don't know the difference between the instrument itself and the installed system.

The FAA required operational accuracy of the altimeter SYSTEM is 75'.

Now, doesn't that make one wonder why such experts would propagate a misleading number? It's quite easy to be mislead by fraudulent use of Internet links unless one knows and understands the system under discussion. Translation= Beware of snake-oil salesmen! To borrow a previous quote: That is student pilot level knowledge.

Turbo obviously does not understand acceleration as applied to aircraft accelerometers as evidenced by BS examples and his statements that the light pole(s) strike would definitely show up in the decoded data. Maybe enough to detect, maybe not depending on the location of the strike on the aircraft. His touting of accelerometer sensitivity is again misleading. How is one suppose to determine the difference between turbulence and a light pole hit? Those light pole were designed to breakaway from strikes by automobiles. I seriously doubt an impact would be distinguishable from normal burps in data by a 757 at 450 + knots.

Using his logic perhaps the - .5 lateral G accompanied by the - 1.08333 longitudinal G (the maximum able to be recorded) in the last frame of the FDR was the light poles. Is that enough, Turbo? Do you want to count that as the light pole strike or is it that suspended wall that you dismissed?

[edit on 30-10-2009 by Reheat]

Gee Dr Pepper; a busy little beaver making false accusations again? It seems that the NASA rocket scientist joined up specifically on October 30 2009 to correct the incessant errors JREF disinformation specialists 911files and Reheat and weedwhacker have been spitting out. Why would Rob Balsamo or one of his friends want to be a NASA rocket scientist?

Hello again Mr. Preston,

Can you please answer me the following, as they are in response to your above post?

- Please show where I made ONE false accusation.
- Please show proof that "R_Mackey" from this thread is a NASA scientist.
- Please provide proof that the 3 member of ATS that you called "disinformation specialists" are in fact that.
- Rob Balsamo nor are any of his minions have a fraction of the mental capacity it takes to work for NASA. You will have to ask Bob why he needs to create socks of JREF members. I haven't a clue.

Can you point out where in the last few pages that Ryan Mackey is in error? John Farmer is infamous for his mathematical errors of epic proportions.

Ryan Mackey didn't post on the past few pages.

Have a great weekend,

Dr. P.


[edit on 30-10-2009 by ImAPepper]

Originally posted by R_Mackey

Originally posted by Pilgrum
You're also not doing your credibility any favours by adhering to a claim that a PA reading at about 100' or less from the ground (within 20' at best) is superior in accuracy to the radio height indication (within 1'). .

The Main altimeter on an aircraft comes off the Air Data Computer. It is based on pressure and is highly accurate.

It is true that the Radar Altimeter is more accurate, but where the difference resides is in the fact Baro Altitude is above a known object (sea level) whereas Radar Altitude is not above any known object. This is why a Baro altimeter is primary for IFR flight and a Radar Altimeter is not even required to fly an approach to minimums served by 99.9% of the flying public.

Being that you know exactly how high you are above a determined object within 20 feet in Baro Alt (MSL), verses the fact you do not know how high you are above any specific object in Radar Altitude, Baro altitude is more accurate for placement of an aircraft in time and space.

The RADALT beats the pressure altitude, this is why they have RADALT. When you land the +-75 of the pressure altitude will not hack it.

www.allstar.fiu.edu...

An aircraft altimeter which has the current altimeter setting applied to the subscale should not have an error of more than ± 50 ft when compared on the ground against a known aerodrome/runway elevation. Altimeter initial certification requirements are ± 20 ft. at sea level increasing to ± 230 ft. at 40,000 ft. If the error is more than ± 50 ft. the accuracy of the altimeter is questionable and the problem should be investigated prior to flight. Investigation could include updating the altimeter setting, comparing with other altimeters, adjusting for height of location of altimeter and many other possibilities.

A radar altimeter indicates absolute altitude above the surface of the earth.

How accurate is the ADC when the aircraft is beyond certification speed and there is no correction value from flight tests, because there was no flight test done at 100 feet MSL above the certification speed? Vmo is 350/355 KCAS? 77 is going 483KIAS at 100 feet MSL.

RADALT = absolute altitude
Altimeter, pressure altitude = many errors checked ON THE GROUND to be ± 50 feet! On the ground, not flying, not flying at 483 KIAS, in a dive, pulling 1.7Gs.

Doubt they flew a 757 at 100 feet MSL, in a dive, pulling 1.7Gs at 483 KIAS to model the pressure altitude errors. What they did was model the 757 pressure altitude errors for landing and normal airspeeds as accurate as they could to gain certification of ± 20 feet at sea level, and ± 230 feet at altitude. This means the RADALT is orders of magnitude more accurate than pressure altitude which in engineering terms means someone is using opinions instead of science.

What does 4 feet mean from the RADALT? Something is 10 feet away from the antenna? What could be 10 feet away from the belly of a 757 going 483 KIAS, in a 3600 foot per minute dive at 1.7g? Not the top of the Pentagon because in less than 1/3 of a second Flight 77 reading 4 feet above the Pentagon roof in a 3600 fpm decent is a crash into the Pentagon.

Originally posted by Reheat
Speaking of mistakes, I wonder why those "verified by the FAA" cult have not corrected "the technologist's" mistake and misleading statements about baro altimeter accuracy. The 20' accuracy that Turbo has been touting is a manufacturer's tolerance on the instrument itself which does not include the piping and other installation issue such as, placement and performance of the static ports. Consequently, it is misleading and WRONG. It is obviously aimed to mislead those who don't know the difference between the instrument itself and the installed system.

Nor does Turbo understand that those numbers he was quoting were for operations within normal operating conditions. Data readouts and data generation from equipment being used outside of normal operating parameters (i.e. excessive speed) can and should be expected to be skewed and erroneous.

Its akin to their "max speed" argument - max speed is max speed and the aircraft cannot go faster than that. PfT aerologic at its finest.

Originally posted by trebor451

Originally posted by Reheat
Speaking of mistakes, I wonder why those "verified by the FAA" cult have not corrected "the technologist's" mistake and misleading statements about baro altimeter accuracy. The 20' accuracy that Turbo has been touting is a manufacturer's tolerance on the instrument itself which does not include the piping and other installation issue such as, placement and performance of the static ports. Consequently, it is misleading and WRONG. It is obviously aimed to mislead those who don't know the difference between the instrument itself and the installed system.

Nor does Turbo understand that those numbers he was quoting were for operations within normal operating conditions.

This is absolutely correct and I failed to include that. It doesn't even have to include any pressure anomalies around the static ports as previously suggested as a potential for errors. Since the altitude signal goes through the Air Data Computer (ADC) and the ADC had never seen that speed at that pressure it's anybody's guess at how that would affect the signal.

Originally posted by Reheat

This is absolutely correct and I failed to include that. It doesn't even have to include any pressure anomalies around the static ports as previously suggested as a potential for errors. Since the altitude signal goes through the Air Data Computer (ADC) and the ADC had never seen that speed at that pressure it's anybody's guess at how that would affect the signal.

Okay, to sum up, Turbo agrees that PA is based on air pressure and is very sensitive to changes in air pressure. As the real Mackey and others have suggested (and I agree with), the excessive speeds at low altitudes would create an abnormal air pressure environment difficult to predict.

Beyond that, there is also the issue of the measurement system operating outside the spec range which may well introduce errors in measurement. So one measurement related to altitude (PA) is in disagreement with four additional measurement systems (the 4 RA's) which even Turbo agrees are more accurate than PA.

So 4 out of 5 measurement systems are consistent with one another and one is not at the end of flight. Would someone remind me what the issue we are debating is again? Sounds like we all agree that the RA is operating within parameters and PA is giving erroneous values.

Originally posted by SPreston
Ryan Mackey is indeed a famous personage, in addition to being a NASA rocket scientist spouting disinformation from the Forum of Magicians and Illusion.

The Short Reign of Ryan Mackey

Why post a nonsensical personal attack from a group of conspiracy theorists who failed to earn Pulitzer Prizes for their delusions about September 11, 2001? Why not present evidence to support the fantastic claims implied by you. The journal of 911 studies publishes biased attacks on people instead of presenting evidence, they choose to attack people presenting facts and evidence instead of backing up their failed fantasies with science; clearly an anti-intellectual approach.

Instead of attacking Ryan Mackey with a “peer” (paranoid conspiracy theorists) reviewed "fake journal" letter, why not study the FDR and come up with evidence to prove how accurate the pressure altimeter is at 483 KIAS, in a dive, pulling 1.7 Gs.

On September 11, 2001 the altimeter setting set on Flight 77 at take off was 30.21. The altimeter reading stored in the FDR was 40 feet, at an actual elevation of 288 feet MSL. Corrected for 30.21 is “exactly” 306 feet. Is that an “exact” 18 foot error?

At 95 KIAS, on the ground, the altimeter reads 65 feet. Corrected for 30.21 we have 331 feet MSL with Flt-77 on the ground at Dulles. A 43 foot error and we are on the ground going 95 knots. What kind of error will be at 483 knots, 3600 fpm decent, pulling an average of 1.7Gs? At 483 knots, 5 times faster, will the error be 100 feet? The fact is Flt-77 impacted the Pentagon making the error “exactly” 98 feet if the last altimeter reading was 0.88 second from the Pentagon as shown on the FDR. Math and research is required.

Flt-77 starts to liftoff; the FDR altimeter value is 49 feet, reading 74 feet 5 seconds before. We lifted the nose gear off the ground and the plane has jumped 25 feet down!? What?, the pressure reading altimeter systems says while we started to liftoff, the plane went down? The exact system has an error. A system checked on the ground to ± 50 feet, the pressure altitude system; who called it exact?

On the runway an error starts at 18 feet, growing to 52 feet, suddenly changing to 27 feet; all on the ground. The RADALT indicates Flt-77 is on the ground, the Pressure reading altimeter says we were at 306 feet, 331 feet, and 315 feet before leaving the ground.

Over the runway, the RADALT reads 99 feet, the pressure altimeter reads 180. The runway elevation is 288 to 310 feet, Flt-77 is actually 387 to 409 feet MSL, and the altimeter reads 446, at best a 37 foot error.

Entertaining the opinion based conspiracy theories; you can use the facts to destroy the delusion. The altimeter reading is an early value of each stored second in the FDR, the last altitude reading of 176 (at 30.22), or 64 feet uncorrected for errors above the roof line. Flt-77 is descending this last second, after the altimeter reading is stored, before the actual impact at the Pentagon Flt-77 will descend another 31 feet to be 33 feet above the roof uncorrected for errors. Take the errors from takeoff of 18 to 52 feet, and we have Flt-77 impacting the roof, or impacting the roof in less than .5 second. However!, we know exactly where Flt-77 impacted, not on the roof but where a jet fuel fireball the exact size for the amount of fuel on Flt-77 was located and where the passenger remains and the FDR were found. Except for delusional claims backed by opinions about Flt-77, the reality based evidence supports Flt-77 impacted the Pentagon.

Maybe I'm getting too lazy to look up operating specs and algorithms so perhaps someone could tell me (and everyone) a little more in-depth info on the radar altimeter operation.

There are 4 of them in this case - are they all in continuous operation and simply polled in sequence at 1 second intervals or is there some averaging function built into either them or the recorder's software?

What I'm getting at is whether the returned readings are instantaneous at the moment of polling or do they have a 'smoothing' function built in. If there's any degree of averaging or smoothing built in to the individual devices' firmware it would rule out a spurious and extremely odd reading like what we'd expect from passing over a car, tree, whatever that could produce a lower reading than actual ground level.

Originally posted by Pilgrum
Maybe I'm getting too lazy to look up operating specs and algorithms so perhaps someone could tell me (and everyone) a little more in-depth info on the radar altimeter operation.

There are 4 of them in this case - are they all in continuous operation and simply polled in sequence at 1 second intervals or is there some averaging function built into either them or the recorder's software?

I believe there only three antennas with one cockpit display. However, the FDR records data from all three inputs individually.

You're really asking this question in the wrong place. You need a highly qualified Avionics Technician. There isn't one here. There is one at JREF who user name is Apathoid. He is currently employed by a major Airline.

If he doesn't know he can look it up in the manuals.

Originally posted by Pilgrum
What I'm getting at is whether the returned readings are instantaneous at the moment of polling or do they have a 'smoothing' function built in. If there's any degree of averaging or smoothing built in to the individual devices' firmware it would rule out a spurious and extremely odd reading like what we'd expect from passing over a car, tree, whatever that could produce a lower reading than actual ground level.

The reading/display is as fast as it takes the radar signal to reflect/return from a reasonably solid radar reflective object. The time (of course) will depend on the distance to the object. There is no processing of the data except to render it on an instrument in altitude type format similar to other cockpit information.

Cars, or a group of trees, etc will reflect, so that's not a spurious or odd return, it is simply something that will reflect the radar. One would be able to interpret these type of returns to distinguish them with ground level returns when actually looking at the display, but on the FDR readout it would not be possible to interpret these as the altitude would be recorded at polling. A radar altitude trend would tell the true story, but not necessarily isolated individual readings. A single tree (depending on size) or pole generally won't reflect. Other items you'll need to ask specifically and I'll give you my opinion on their reflectivity based on experience.

Here is the Data Frame layout from the NTSB which might help with some of your questions.

warrenstutt.com...

[edit on 31-10-2009 by Reheat]

[edit on 31-10-2009 by Reheat]