Flight 77 FDR research

Everyone,

These are the two data sets I've been able to download from P4911T. The first is what I'm calling tabular and the second is what I'm calling L3 data. A segment of the first page from each is shown below.

These have been converted to jpeg from the original excel .cvs format, so the borders and row/column numbers ae not visible.

Are we all examining the same data?
Thanks

Tabular


L3

The tabular file I downloaded included pressure alt in feet and 2 altimeter settings CAPT and FO.

My tabular file shows altimeter reset to 30.22 on decent but P4911T states that the animation is based on 29.92. What gives?

My tabular file does not include inertial lat and long NAV readings but the L3 files does.

The NAV data plots like this according to the L3 file:



Why does the P4911T site show the last NAV data point at impact instead of the reported coordinates at 13:37:45 GMT?

Originally posted by darkbluesky
The tabular file I downloaded included pressure alt in feet and 2 altimeter settings CAPT and FO.

Thank you for answering that and for the Jpegs! This is very helpful. So L3 is the other file at the Pilots' site. Be sure also to chaeck the specialists' study. I can't understand all the params there... I think we have the sources sorted out now.

My tabular file shows altimeter reset to 30.22 on decent but P4911T states that the animation is based on 29.92. What gives?

a cover-up of the true alt, a fake animation, a fake CSV file, both fake, etc...

My tabular file does not include inertial lat and long NAV readings but the L3 files does.

Intersting...

The NAV data plots like this according to the L3 file:
(image) Why does the P4911T site show the last NAV data point at impact instead of the reported coordinates at 13:37:45 GMT?

You can seriously map this? I'm curious how you achieved that. If correct, this conflicts with the animation, showing a route south of the Citgo after all... What is TAS? Speed, right? EXCELLENT work, just hoping for clarification on how you mapped this and how accurate or off it may be.



[edit on 6-3-2007 by Caustic Logic]

Originally posted by darkbluesky
The tabular file I downloaded included pressure alt in feet and 2 altimeter settings CAPT and FO.

My tabular file shows altimeter reset to 30.22 on decent but P4911T states that the animation is based on 29.92. What gives?

I believe that Pressure altitude is recorded through the ADC (air data computer) at 2992 and then plotted/corrected according to the altimter setting on the Capt/FO altimeters.

I believe the reason they do this is that all three units. FDR, Capt. Alt and F/O Alt get their information from the same source the ADC. No sense in recording the identical same data from the three units just record it from the FDR and then correct it for the altimeter settings.

The animation is based on FDR Pressure altitude corrected for Capt's and F/O's altimeter setting.

If you ask what about if there is a difference between the Capts. and the F/O's altimeter setting I would respond that the Capts and F/O's alltimeters, set to the same barometric pressure have to indicate within a few feet for dispatch. I don't remember what it is but its not very much.

TAS = True Airspeed and is the IAS (indicated airspeed) corrected for altitude. The correction is 2% for every 1,000 ft altitude (e.g. at 0 ft 250kts IAS = 250 kts TAS, at 5,000ft ft, 250 kts IAS = 275 kts TAS).

At 500 ft, 450 TAS = 445 kts IAS (approx). The FDR should show that there is an overspeed alert, as Vmo (Velocity Max Operating) at that altitude for a 757 is approx. 350 kts IAS.

[edit on 6-3-2007 by mirageofdeceit]

Originally posted by mirageofdeceit
TAS = True Airspeed and is the IAS (indicated airspeed) corrected for altitude. The correction is 2% for every 1,000 ft altitude (e.g. at 0 ft 250kts IAS = 250 kts TAS, at 5,000ft ft, 250 kts IAS = 275 kts TAS).

At 500 ft, 450 TAS = 445 kts IAS (approx). The FDR should show that there is an overspeed alert, as Vmo (Velocity Max Operating) at that altitude for a 757 is approx. 350 kts IAS.

I looked at all the channels and could not find one for overspeed warning horn. All Transport Category certifcated airplanes have an aural warning horn for that and that would be recorded on the cockpit voice recorder.

Voice recorders are synchronized with the FDR during the investigation. If we had the voice recorder we could hear how the pilot or pilots obtained the current altimeter setting at 09:24:15 which is the time that both altimeters were reset.

Voice recorder loops are only 30 minutes long so as the crash was at 09:37 that information would still be on there. I also noticed that both the altimeters were set within 1 second of each other. I don't think if there was one pilot that he could set the captains altimeter and then reach over and set the copilots altimeter in 1 second.

You can seriously map this? I'm curious how you achieved that. If correct, this conflicts with the animation, showing a route south of the Citgo after all... What is TAS? Speed, right? EXCELLENT work, just hoping for clarification on how you mapped this and how accurate or off it may be.



[edit on 6-3-2007 by Caustic Logic]

Google earth displays lat and long of your cursor position accurate to 1/1000th second.

Simple matter to convert decimal degrees from DFDR to deg min sec with any scientific calculator or web site conversion program.

Then just find the lat and long on Google earth w/ the cursor and place a thumb tack. I think thats all P4911T did for two of their visual references. But they placed the last frame of DFDR data Time 13:47:45 at the Pentagon but the data clearly shows the last position reported was well SW of the Navy Annex.

This is the plot P4911T created:

Ooops - forgot about the CVR.

Descending at 5,500 ft/min leveling off for 239 ft is impressive stuff! SOOO impressive in fact, it can't be done in the real thing.

They would have to have started pulling up at 1,500ft to 2,000ft to avoid terra firma at that rate of descent (what was the g for this period???), meaning the rate of descent is a lot lower over this period than quoted in the pic above.

There is something WAY wrong with that. Even pulling the thing around like a fighter (possible to do) would make that maneuver very tough (read: impossible on the first try) for someone with no experience of inertia in a large jet like that, and at those speeds. That is some precise flying that only experience can bring, assuming the numbers are accurate at all (I suspect they are doctored and it never performed that maneuver).

Assuming 235ft is the actual altitude of the aircraft at the end f the 10 second period, that puts them only 60 ft above the ground after leveling off. I think even a fighter would be struggling to pull that off with those margins. A bit of quick work with the pitch and power is required to do it. What does the FDR show for this period (control position, pitch, power and g)?

[edit on 7-3-2007 by mirageofdeceit]

Originally posted by mirageofdeceit
Assuming 235ft is the actual altitude of the aircraft at the end f the 10 second period, that puts them only 60 ft above the ground after leveling off. I think even a fighter would be struggling to pull that off with those margins. A bit of quick work with the pitch and power is required to do it. What does the FDR show for this period (control position, pitch, power and g)?

For the last 60 seconds of flight the FDR Channel B (vertical acceleration) shows starting at 09:36:46 1.089 G's, at a pressure altitude of 869 feet with a maximum of 1.753 G's pressure altitude 307 feet recorded at 09:37:42 about 4 seconds before the alleged crash at 09:37:46 at which the vertical acceleration was recorded to be .618 G's at a pressure altitude of 173 feet.

I mis-understood what was being said regarding the 5,500 ft/min rate of descent. The last ten seconds of flight (up to immediately before impact). That makes more sense.

1.75g isn't much, even in terms of a commercial airliner, and now I'm not confused over the above, doesn't seem too odd.

I did spot this oddity in the CSV file of the FDR data: at 08:26:52 (around 15,000 ft) the F/O set his altimeter to 29.92.

Around 08:28:06 and passing 18,000 ft the Captain then set his altimeter to 29.92. Was the F/O PF on that flight, and set his altimeter early to avoid an altitude bust? He sets it over a minute before the Captain, and 3,000 ft below transition altitude.

I note that during this period there are no jumps in the FDR recorded altitude.

Later they are cleared from FL330 to FL350 (FMC step-climb or ATC)?

After that, they remain at FL350 from 08:45:54 to 09:01:14 (16 minutes), at which point they descend to FL250 in FL CH mode. The FMC has a message at this point (??? RESET MCP ALT ???). I know that if you change the altitude in the MCP (Mode Control Panel, often mis-referenced as the autopilot which is actually in the avionics bay) the new altitude appears in the FMC scratch pad after 5 seconds, but this does not generate an FMC MSG alert. FMC Messages must be cleared before the scratch pad can be used again by pressing the CLR button. Only the last message to occur is displayed.

The engines come back to approx, 50% N1 as the rate of descent increases.

The FMC message first occurs at 08:59:04 which is most likely a RESET MCP ALT alert, to tell the pilots the aircraft wants to change altitude, but there is an altitude constraint (the MCP altitude) preventing it. The pilots have to change the altitude to the new cleared altitude (as directed by ATC) then clear the FMC to descend by pressing VNAV. By going into FL CH mode, they have overridden the FMC vertical flight plan and gone into manual FLight CHange mode on the MCP.

3 minutes later, the aircraft starts a descent to FL250.

At 09:02:04 the FMC message is cleared.

****** Do we know the route this aircraft was flying that day?? ******

At 09:06:35 the aircraft levels off at FL250.

At 09:07:52 the AP is disconnected.

At 08:56:34 the transponder is switched off.

Note that I went back in time there. The FMC messages do NOT clear themselves. If there is a message, it shall remain. I doubt VERY much that the hijackers would go to the trouble of clearing this message, or would even know HOW to clear it. I'm also surprised that they knew what FL CH mode on the MCP did, as its function is not self-explanatory, or why they would use it to descend initially, only to disengage the autopilot for what happens next.

I've also been examining the DME distances. NAV1 was tuned to DCA (Washington D. C. 111.00 MHz as of 2004). This matches with the DME distance of 1.5 nm from the point of impact.

What I can't get to tally is the DME2 distance. This reads 3.2 nm DME at the point of impact in the FDR data, but the next closest VOR/DME to the crash site is ADW (Andrews, Washington D. C.) at 10 nm.

Where is this ghost DME???

Note that the VOR/DME system of the aircraft would have been in AUTO mode during the initial, normal part of the flight. The purpose of the system is to tune specifically DME stations, that have known points in space, so that the IRS system (Inertial Reference System) can update its position and keep the navigation accuracy of the system high. The IRS is an inertial platform comprising of laser ring gyros that tell the aircraft its latitude and longitude, as well as providing attitude reference and heading data that are displayed on the primary flight displays.

The system will attempt to tune one station on-track (that is, immediately ahead of the aircraft, or as close as this as possible), whilst tuning the other radio to an off-track DME station. This is so it can determine its position as accurately as possible.

[edit on 7-3-2007 by mirageofdeceit]

I quote myself

I note that during this period there are no jumps in the FDR recorded altitude.

This confirms that the FDR is assuming 29.92 in Hg in its recording.

This puts the aircraft too high above the building, as discussed earlier in the thread.

QUESTIONS:

* If it didn't crash, where did it go?

* There is an airport 1.5 nm due East of where the aircraft was alleged to have crashed. If it didn't crash, did any one in the tower at the airport see the/an aircraft flying low-level? It would have flown directly past the end of one of its runways (RW19/RW01).

* Is the reason no-one in the area reports strange low-flying aircraft due to the fact the airport is so close, and it is a normal occurrence and therefore not "odd"?

* Did any aircraft make an unscheduled landing at the airport (KDCA - Ronald Reagan Washington National)?

* The crash would have sent a plume of smoke up into the extended centerline of RW15/RW33 at KDCA; was anyone notified, and what action was taken at KDCA?

KDCA Field Elevation is 16 ft. 175 ft is still 164 ft above the ground, and still 89 ft above the roof of the Pentagon, assuming the altitude in the FDR is correct and is the actual aircraft altitude. It STILL didn't hit the building, even if the FDR is 100% correct. (WTF? ).

External Source

Yellow Line: Flight path of AA77
Red Line: Extended centerline of RW19, KDCA
Green Line: Extended centerline of affected runway
Blue Square: Location of ATC on the airport



[edit on 7-3-2007 by mirageofdeceit]

Originally posted by mirageofdeceit
dd.

I did spot this oddity in the CSV file of the FDR data: at 08:26:52 (around 15,000 ft) the F/O set his altimeter to 29.92.

Around 08:28:06 and passing 18,000 ft the Captain then set his altimeter to 29.92. Was the F/O PF on that flight, and set his altimeter early to avoid an altitude bust? He sets it over a minute before the Captain, and 3,000 ft below transition altitude.

I speculate that they had already been cleared above TA and when that happened he set 2992. It is not a good practice but it is done.

I note that during this period there are no jumps in the FDR recorded altitude.

No, FDR will not jump anywhere, it is set to 2992.

Later they are cleared from FL330 to FL350 (FMC step-climb or ATC)?

So the hijackers have not taken control yet because they would have no reason to comply with the altitude change since they know they are going to be headed back the other way.

After that, they remain at FL350 from 08:45:54 to 09:01:14 (16 minutes), at which point they descend to FL250 in FL CH mode. The FMC has a message at this point (??? RESET MCP ALT ???). I know that if you change the altitude in the MCP (Mode Control Panel, often mis-referenced as the autopilot which is actually in the avionics bay) the new altitude appears in the FMC scratch pad after 5 seconds, but this does not generate an FMC MSG alert. FMC Messages must be cleared before the scratch pad can be used again by pressing the CLR button. Only the last message to occur is displayed.

Any knob controlling autopilot functions are commonly referred to as 'autopilot'. The autopilot unit is indeed in the bay but it is not referred to as the "autopilot in the avionics bay," neither does anybody think of the 'autopilot' as being in the avionics bay. The autopilot is any knob you can touch with your fingers that controls autopilot function.

The engines come back to approx, 50% N1 as the rate of descent increases.

The FMC message first occurs at 08:59:04 which is most likely a RESET MCP ALT alert, to tell the pilots the aircraft wants to change altitude, but there is an altitude constraint (the MCP altitude) preventing it. The pilots have to change the altitude to the new cleared altitude (as directed by ATC) then clear the FMC to descend by pressing VNAV. By going into FL CH mode, they have overridden the FMC vertical flight plan and gone into manual FLight CHange mode on the MCP.

3 minutes later, the aircraft starts a descent to FL250.

At 09:02:04 the FMC message is cleared.

****** Do we know the route this aircraft was flying that day?? ******

At 09:06:35 the aircraft levels off at FL250.

At 09:07:52 the AP is disconnected.

At 08:56:34 the transponder is switched off.

Note that I went back in time there. The FMC messages do NOT clear themselves. If there is a message, it shall remain. I doubt VERY much that the hijackers would go to the trouble of clearing this message, or would even know HOW to clear it. I'm also surprised that they knew what FL CH mode on the MCP did, as its function is not self-explanatory, or why they would use it to descend initially, only to disengage the autopilot for what happens next.

Ok so up to now they have had a pretty smooth flight. There is no indication that a hijacker has taken over. Surely if the pilots would have been threatened with a knife they would have half-rolled the airplane and pushed forward to bang the hijacker on his head upside down. Surely if the airplane has been taken over there is going to be an indication that less experienced pilot has taken over, in other words, no use of the autopilot, sharp jerky use of the controls. But we have a nice, calm , orderly descent and both the Capt and the F/O professionaly reset their altimeters at exactly FL180. Continued use of the autopilot down to 7000 feet.

All I am asking is when were the pilots killed and dragged out of their seats or at least when was the captain dragged out of his seat? You would think that dragging a dead capatin out of his seat would show up on the flight controls, either aileron or elevator input as the hijacker tried to pull 180 pounds of dead weight dripping with blood. You would also think that if you killed 2 pilots with a knife that there might be a little bood around and make it slippery and very difficult to drag anybody anywhere.

But lets say the hijacker did manage to get the captain out out of his seat and his body stowed against the cockpit door and then managed to get in the captains seat its going to be very wet with blood. And even if there is no blood imagine the organized, calm, cool descent with the use of autopilot going on while all of this is happening? I find that difficult if not impossible to believe.

I've also been examining the DME distances. NAV1 was tuned to DCA (Washington D. C. 111.00 MHz as of 2004). This matches with the DME distance of 1.5 nm from the point of impact.

What I can't get to tally is the DME2 distance. This reads 3.2 nm DME at the point of impact in the FDR data, but the next closest VOR/DME to the crash site is ADW (Andrews, Washington D. C.) at 10 nm. Where is this ghost DME???

Try one of the ILS freqs. for DCA and see what you come up with. I don't have current charts. Maybe Bolling field has a secret DME?

Continued use of the autopilot down to 7000 feet.

Really?! My data shows the AP to be disconnected (unless I'm looking at the wrong AP channel). I'll double-check. Once they start descending out of FL250, the altitudes aren't held very well, and certainly don't suggest the use of the autopilot.

EDIT: They go from the Right AP channel to the Left AP channel. It is switched on/off/on during the descent starting at FL230, then they climb back up to FL253 using FL CH, then it levels off at FL253. It then shows that they descend to 7,500 ft using the AP, then the AP is disconnected again, then they're looking for the building, then clearly they see it and start their descent.

Bolling Field??? I don't see this on my chart. I see a Bower Field (SSE of DCA).

It can't be an ILS as the NAV boxes on the 757 can't tune ILS frequencies; this is tuned in the FMC or on a seperate ILS box (if equipped).

[edit on 7-3-2007 by mirageofdeceit]

Originally posted by mirageofdeceit
I mis-understood what was being said regarding the 5,500 ft/min rate of descent. The last ten seconds of flight (up to immediately before impact). That makes more sense.

I'm taking that as a clue people are learning here. the thread that started retrded is evolving. I'm also learning, just watching. Good stuff guys! still no new thoughts, no burst a math membrane, but this is taking on less numerical and more human/pilot values that I can actually visualize thanks to your translations. As for what it all means, I'm not sure of that. no time to read it closely now.

Originally posted by mirageofdeceit
I mis-understood what was being said regarding the 5,500 ft/min rate of descent. The last ten seconds of flight (up to immediately before impact). That makes more sense.

I'm taking that as a clue people are learning here. the thread that started retrded is evolving. I'm also learning, just watching. Good stuff guys! still no new thoughts, no burst a math membrane, but this is taking on less numerical and more human/pilot values that I can actually visualize thanks to your translations. As for what it all means, I'm not sure of that. no time to read it closely now.

Originally posted by mirageofdeceit
Bolling Field??? I don't see this on my chart.

Here it is on my chart, its just across the river. I can't imagine why it isn't on your chart.

It is certainly looking like:

* It didn't get close to hitting the Pentagon

* Someone with a bit more training than simply flying Cessnas was flying the aircraft, and tried to make it look like a novice was flying, but automated responses kicked in (such as clearing FMC messages) and other actions that they probably didn't realize they were taking at the time.

It isn't on my chart, and I just realized, I never saw it on Google Maps, either, look. Does it "officially" exist?

Its non-existance would certainly explain the 3.2 nm DME reading (it would be about right); Autotune doesn't care for the source, so long as it has a valid one.




[edit on 7-3-2007 by mirageofdeceit]

Originally posted by mirageofdeceit
It isn't on my chart, and I just realized, I never saw it on Google Maps, either, look. Does it "officially" exist?

WHOOPS! Sorry mirageofdeceit. I accidentally pulled out my sectional chart from 1949. That was there 58 years ago. Please accept my apologies.

No problems!

It does work out at 3.2 nm though..... maybe the DME lives on?

I can't find anything that looks like a DME within 3.2 nm. I did wonder if the Whitehouse had a DME? Is that close enough to count as a source?

[edit on 7-3-2007 by mirageofdeceit]