bje
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Could those readings be consistent with the starboard engine impact with the construction trailer?
AA77 FDR Data, Explained
- Thread starter Anti-sophist
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Could those readings be consistent with the starboard engine impact with the construction trailer?
Yes, that could be the cause of the lateral deaccel, but not likely the longitudinal of -1. I don't think the light poles would cause that much burp either way. Depending on where the light pole(s) struck we might not detect them at all.
Remember, since full throttle (or near that) was likely being used an engine flameout or explosion/seize could cause that kind of burp, as well, both ways.
As beachnut indicated it might help to know which direction is negative on lateral deaccel.
It's all a guess at this point. I don't think the expertise to resolve it precisely exists outside of industry experts, NTSB, FDR Manufacturer, Boeing, et al. That's why it takes months for a full NTSB accident investigation to conclude. We'll likely never see that as it's not important in the grand scheme of things.
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You are right, the -1 g long accer, is like stopping, you would feel you full weight wanting to go forward. .3 take off is feeling .3 of your weight pushed back in the seat.
that is longitudinal, the back and forth, like stopping in the car. The lateral is turning (side to side), being pushed against the door of your car, or away.
Could check a ground turn for takeoff to figure out sign and direction.
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Thanks for the compliment. I started to learn about computers and programing in 1980, so I guess that makes me a computer nerd of the 80s as well.God, I love geeks. Doesn't matter the topic nor how well I understand it, I stand in awe of thems, like Warren, what can make sense of it. And, as a computer nerd of the 80s, I understand both the difficulty and the need to make sense from insufficient data. Honestly, you kids these days? TOTALLY spoiled.
Warren.
I'll be adding the PITCH ANGLE CAPT, PITCH ANGLE F/O and PITCH ANGLE IRU parameters to the next release. I haven't yet found a parameter for VVI. The parameters are listed in the data frame layouts 757-3b_1.txt and D226A101-3G.pdf and in the NTSB's American Airlines Flight 77 FDR Report. If anyone finds a parameter that they believe is VVI or any other parameters they would like to see decoded, let me know.
Warren.
I sure would have thought it would be there, but it isn't. It's a fairly important indicator. Hmmm.
What is also interesting about that LONGITUDINAL ACCEL (G's) value of 1.083 is that it is the most negative value that the FDR can record. Note that the Raw LONGITUDINAL ACCEL value which that value is calculated from is 0. The raw value is an unsigned integer and my program calculates the value in G's from the raw value using the formula:
Value in G's = (5.0 / 1023) * 0.4166666 * Raw Value - 1.083333
I speculate that the actual deceleration of the aircraft was greater than 1.083 G's and the FDR recorded the greatest deceleration it could.
I don't understand what you mean by this, although word 243 in subframe 4 was the last word recorded in the final incomplete frame.
Warren.
How do you know this Warren?
In my opinion, there are only two possibilities that could cause that much deceleration, a flame out or impact with the wall. Most likely the latter. None of the other obstacles encountered would result in that great a value. Opinion - beachnut?
Pitch attitude will likely tell us what we need to know. I believe 3 degrees up was level flight at cruise, correct?
Well, since he's reverse engineered the Huffman tables, this is probably the maximum quantization of that measurement. Seems plausible. Nothing short of collision should give you a reading this high...
... unless it's averaged over a short period, and it's an instantaneous measurement. For example, the Space Shuttle sees a bit more than a 10 g (RMS) vibration at fundamental mode, but it only accelerates at up to about 3.5 g on average.
But I greatly doubt this measurement is capturing a vibration. I'm guessing it's either a preliminary impact, e.g. hitting the generators, or it's the real thing, or it's a preliminary impact that tore the accelerometer from its housing.
Very interesting this additional data is turning out to be.
ETA: Actually, a full-rate value like this (viz. "the highest number that it goes to") is usually a suspicious result, indicative of sensor failure. But since this value is coupled to another accelerometer value that is extremely high but not full-rate, it's more credible. At least I assume the lateral acceleration isn't pegged, is that the case?
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I fogot to point out the same when I posted the last value ...
Uid: LNG_ACCL
Abbrev: LNG_ACCL
Name: LONGITUDINAL ACCEL
Units: G's
Minimum Value: -1.08333
Maximum Value: 0.999498
Digits Displayed: 3
Signed Value: No
Parameter Type: Linear
Format is y = m*x + b: m = 0.002036, b = -1.08333
Sampling Freq.(hz): 4
Number of bits: 10
Locations/value: 1
Frame(s) Subframe(s) Word Start Bit End Bit
ALL 1234 33 3 12
ALL 1234 97 3 12
ALL 1234 161 3 12
ALL 1234 225 3 12
Number of Tests: 0
The data frame layout (757-3b_1.txt) is available here.
http://warrenstutt.com/NTSBFOIARequest2-1-09/index.html
That is not the last second of longitudinal acceleration; it is the last quarter of a second longitudinal acceleration. Sampled at 4 hz, someone will have to explain hz to Balsamo.
The final value could be in error, but to get close to this value would take hitting something substantial when you are going 483 knots accelerating. The max values for lateral acceleration are the same limits so the last lateral reading is not full scale at -0.564g.
0.019 0.21
-0.007 0.014
-0.18 0.118
-0.564 -1.083
This is the last second of lat and long accelerations respectively. From Warren's decode.
I can't figure out if bobbies dolt act is for real or just to sell DVDs to those who refuse to think for themselves outside the p4t pit of ignorance. Hard to find groups who actively strive to excel at ignorance and succeed as well as the drank the kool-aid p4t terrorists loyalists.
This is funny; I will post the ver accer in a second.
Capt truthNAZI Balsamo here are the seconds the NTSB gave to you years ago and you failed to decode them! Sad.
BTW, the 1.66 G is in the final four seconds! Game, set, match.
These are the last 4 seconds of data with average G each 8 samples of G,
0.725
0.659
0.92
0.858
0.94
1.121
0.828
0.783 0.85425
0.982
0.986
0.927
0.776
1.25
1.037
1.231
1.721 1.11375
1.604
1.781
1.762
1.964
1.879
2.264
2.044
2.181 1.934875
1.675
1.744
1.65
1.504
1.785
1.655
1.861
1.945 1.727375
Balsamo is the anti-mind reading expert.
Mackey wins the million! Balsamo is such a fraud. If only he did math. Okay, Balsamo is no act, he is dirt dumb stupid and he sells his moronic poppycock on DVD, now on sale in a 6 pack or some nonsense.
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Actually, it's not a "guess" -- it is, in fact, a "theoretical prediction confirmed by new data." Maybe we could have had the data years ago, but that's not the point. The point is, the more we uncover, the better our theory looks.
That's theory, not hypothesis, because it passes predictions just like these. Science wins again. Always does, because science is patient.
And the lack of science is,
, Balsamo.
According to page E1 of D226A101-3G.pdf a positive lateral acceleration is right in the same way that a positive longitudinal accelerate is forward.
I tried decoding that parameter but I got nonsense values. Check out my Notes on Parameters for the AAL77 FDR Decoder web page.
Warren.
ETA: I'll look for it within the data.
ETA: Fixed grammar.
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