FAA ATC Audio Anomalies

[TheLoneBedouin]

However, it is still right there at AAL77.COM where it has always been. Please try to stay on topic TLB.

Sorry but I can't seem to find the article that was included in Gaffney's book on your site.

Can you provide a link?

You know, it's the one where you assert a 2-plane conspiracy theory involving a north side flyover of an E4B at the time of the attack.

Gaffney states outright in the book that it supports the notion that the RADES data had been manipulated. Naturally a north side flyover of ANYTHING at the time of the attack would require the data to be doctored.

Here is what Gaffney said on page 102:

At my request, Farmer drafted a somewhat-less-technical paper summarizing his two-year investigation of the Pentagon event. (It is attached as an Afterword to this book.) He presents both physical evidence and eyewitness testimony that a second plane was in the vicinity at the time of the Pentagon strike. He thinks this other plane may have shadowed whatever struck the building. Farmer's paper is relevant to this discussion, because there is no hint in the RADES radar data that a second plane was in the area.

So obviously it DOES support evidence manipulation and therefore IS relevant.

Interesting how it is introduced as a "summary" of your 2-year "investgiation" which is very much how it reads.

Got a link to the article as it was published in the book?

 

[BCR]

Sorry but I can't seem to find the article that was included in Gaffney's book on your site.

Can you provide a link?

You know, it's the one where you assert a 2-plane conspiracy theory involving a north side flyover of an E4B at the time of the attack.

Gaffney states outright in the book that it supports the notion that the RADES data had been manipulated. Naturally a north side flyover of ANYTHING at the time of the attack would require the data to be doctored.

Here is what Gaffney said on page 102:


So obviously it DOES support evidence manipulation and therefore IS relevant.

Interesting how it is introduced as a "summary" of your 2-year "investgiation" which is very much how it reads.

Got a link to the article as it was published in the book?

You sure got a way of derailing a thread TLB. It is not the subject of this thread and is not related to this thread, an FAA ATC audio anomaly is. Your questions are addressed in another thread and it is linked there where it is the topic.

 

[gumboot]

Another good point. I am assuming that there is only one original record. I'm not sure why there would be more than one, but might be something to consider.

I think it would be an almost certainty that there's more than one source because DAT only carries four channels at most, so that means only 3 audio channels per recorder. Even assuming you had some sort of super DAT that carried dozens of different channels on one tape, you can still have interference from the input of one channel that gives it an anomaly.

What you potentially have here is multiple source inputs going to multiple recorders, and then being stored for a period of time in a perishable format before being digitised.

There's veritable oceans of opportunities for data corruption, without bringing redaction into the mix.

This is the FAA regulation relating to the use of recorders, and makes it clear that there would normally be many different recorders in use.

I believe the number after the facility code (in this case 108 and 98) refers to the recorder number.

 

[beachnut]

You sure got a way of derailing a thread TLB. It is not the subject of this thread and is not related to this thread, an FAA ATC audio anomaly is. Your questions are addressed in another thread and it is linked there where it is the topic.

He likes you.

Good luck on your tape stuff. I doubt anyone altered your tapes on purpose.

 

[ktesibios]

I downloaded the two files 911fileslinked to in the OP, imported them into a ProTools session and started looking for the item which most interested me- the dropout shown in the first screencap in the OP.

Despite scrolling through the whole thing at a zoom which would have made a ten second dropout obvious I could not find it. Since this apparently occurs at 13:51 (UTC?) and the filename implies that it contains only 13:29 to 13:44, I assume that it would be after the end of the file.

I'd really like to take a close look at the change in amplitude of the timing signal shown in the second screencap, but unless I know exactly where it is relative to the beginning of the audio file I'm unlikely to be able to find it.

What I want to look for there is any waveform discontinuities which might indicate an edit. The mere fact that the amplitude changes is not in itself particularly suspicious; small (<1 dB) changes in recording sensitivity along the length of a reel are actually pretty common in analog recording (some of the newer high-output "+9" tapes such as Quantegy's 499 & GP-9 are particularly annoying in this regard).

The dropout doesn't strike me as suspiocious per se either. The screencap in the OP shows it as having a duration of about 10 seconds, which could well be the result of the copyist leaving the digital recording running while changing tapes on the source machine.

The timing signal appears to be a mid-frequency tone, amplitude modulated so as to produce a 2-cycle burst at a higher level every 10 mS, with longer bursts apparently marking 100 mS and 1S intervals. If my eyeball guess is correct, it wouldn't be hard to design a bit of circuitry which would keep track of elapsed time on the tape, which, if the start time of the recording is known, would give you time-of-day.

IMHO, this is a damnably cheesy way of putting a timestamp on the recording. All the FAA would need to do is to pick up a SMPTE timecode generator on eBay, preset the generator and start it in sync with the clock on the wall, let it run continuously and presto! a continuous timestamp on the tape, with 33 mS resolution, readable with common off-the-shelf hardware (there are even drum machines that can read SMPTE, for "Bob"'s sake), providing the ability to synchronize tapes from different recorders (providing they all have the same timecode stirped on them) and extremely difficult to edit without producing an easily detectable discontinuity in the time data.

 

[BCR]

Unfortunately I wanted to have equivalent samples and the gap was not covered by both files. I can trim a wav file with just the gap, or a larger one with the entire anomaly. Just let me know which you prefer (file size constraints for downloading). I am in the process of decoding the time waveform (right-channel) and I'll post the results once completed. At this point I can tell you that it is a 1000 bit per second block, seperated into 100 bit data fields (the 100ms you refered to) by the 1111111100 seperator. 1100000000 = 0 and 1111100000 = 1 in binary. There seems to be a conversion to Hex involved which I am working on currently.

Thanks for taking a look at it and let me know which segment of the wav file you need and I'll get it uploaded for you to download.

FYI: Each data block begins with two seperators 1111111100 1111111100, and the first data field is seconds. 1's and 0's being represented by amplitude change.

 

[Cheap Shot]

IMHO, this is a damnably cheesy way of putting a timestamp on the recording. All the FAA would need to do is to pick up a SMPTE timecode generator on eBay, preset the generator and start it in sync with the clock on the wall, let it run continuously and presto! a continuous timestamp on the tape, with 33 mS resolution, readable with common off-the-shelf hardware (there are even drum machines that can read SMPTE, for "Bob"'s sake), providing the ability to synchronize tapes from different recorders (providing they all have the same timecode stirped on them) and extremely difficult to edit without producing an easily detectable discontinuity in the time data.

The FAA went digital a while back, the old recorder is sitting on top of filing cabinet in the basement at Boston Center. In some incidents it is not uncommon for the Q&A specialists remove dead time from a tape, no one wants to listen to two minutes of dead time, I doubt they did it with tapes from 9-11, but you never know.

 

[gumboot]

IMHO, this is a damnably cheesy way of putting a timestamp on the recording. All the FAA would need to do is to pick up a SMPTE timecode generator on eBay, preset the generator and start it in sync with the clock on the wall, let it run continuously and presto! a continuous timestamp on the tape, with 33 mS resolution, readable with common off-the-shelf hardware (there are even drum machines that can read SMPTE, for "Bob"'s sake), providing the ability to synchronize tapes from different recorders (providing they all have the same timecode stirped on them) and extremely difficult to edit without producing an easily detectable discontinuity in the time data.

Some FAA facilities were still using a voice time stamp back then, like the NORAD recordings.

 

[BCR]

DCA 98 Extended Segment (187mb)