United Flight 93, What actually happened ? [somewhat edited by JT]

[SUPERMNNN]

Transponder signals again:

I couldn't give up on this two signals. Even if the transponder switched on by itself, or some kind of malfunction. It must gave out ID signal and altitude, so the control center could spotted it. The altitude 6400 ft and 59 or 5800 ft should be the correct height at the time of the signal was transmitted. (from Tom Brokaw's interview with an air controler who was on duty watching flight 93 at the time.)

This is the reason I asked for the transponder, Gary. You do need to have a transponder to get into airport airspace, don't you? In order to avoid traffic accident, to arrange landing with the ATC, do you need to send in your id and altitude? If an airport doesn't have a control tower, does it mean that there is no ATC?

As a pilot, before landing, do you check your tranponder to make sure it is on or not? Can ATC allow you to land without a transponder?

The airport I showed you is an airport 6 miles west (a little bit north) of the crash site, Somerset County Airport. The runway direction is that you have to land from N.E to S.W, I believe.

The debris fields were three islated locations. If the wind blow light debris 8 miles south, we should see a scattering debris field like a quarter of a circle (maybe a slice of pizza shaped), centered at the crash site. Isolated fields tell you that the debris were directly fall from the plane, which would give you the path of the plane, it didn't matter what caused the debris, as long as they were directly fall from the plane.

If you look at these locations on the map: draw a line from Cleveland OH to Washington DC (Flight 93 was moving from Cleveland towards DC before the crash). Then if you look at New Baltimore PA, Indian Lake PA, the crash site, doesn't it tell you that Flight 93 flying towards DC, then turned around, passed New Baltimore, Indian Lake, then crashed on Shanksville? Then you add this airport on the map. What does it tell you? As a professional pilot? Do the two tranponder signals make sense?

For this airport
http://www.airnav.com/airport/2G9/A

Then add the fact that there were one professional commercial pilot on flight 93 and an air traffic controler as passengers.

No fictional speculations (only some assumptions supported by facts and calculations.)

[bmoorhouse]

Originally Posted by john_tullamarine

I think that the conspiracy things are best left to other sites .... while the techie bits certainly can remain here ...

Seems to me that SUPERMMM is back on the conspiracy path again. Isn't it time to close this post and advise SUPERMMM to go to his local library to do some basic research on aviation?

All my previous posts have been "moderated" away, so i'll back out of this topic now.

[Groucho]

Seconded!

Bin or Jet Blast please JT!

[fyrefli]

Originally Posted by bmoorhouse

Seems to me that SUPERMMM is back on the conspiracy path again.

But he's not! He's actually said quite explicitly (twice IIRC, although one may have been removed) that his instincts are quite the opposite and that he's merely trying to make logical sense of the data. The problem with the Popular Mechanics "debunking" is it's shot full of holes (I'll not go into its ownership; again you can use Google). SUPERMMM is trying to redo their shoddy job properly.

Just because his English isn't brilliant doesn't mean that his Physics is dodgy.

Cheers,

Rich.

[eastern wiseguy]

You do need to have a transponder to get into airport airspace, don't you? In order to avoid traffic accident, to arrange landing with the ATC, do you need to send in your id and altitude? If an airport doesn't have a control tower, does it mean that there is no ATC?

As a pilot, before landing, do you check your tranponder to make sure it is on or not? Can ATC allow you to land without a transponder?

In order(UK ONLY but PROBABLY similar in the rest of the world)

Not Neccessarily

Yes...but there is also PROCEDURAL airspace which has NO radar and therefore the information is transmitted orally

ATC can be provided (at the lowest level of equipment) by a person with a radio and a clock. There is no need for a tower(although your question is odd and doesn't seem to ask what you want answering)

ATC (in my experience)are the folks who would normally alert aircrew to the fact that the aircraft transponder is working or not. Looking at a display a controller will validate and verify the squawk(asssigned transponder code)on departure.That is to say the aircraft is using the ASSIGNED code and that the Mode C (height readout)is within tolerance. Thereafter the transponder would generally be ignored by the flight crew.

Yes ...see above.

[Slopey]

Ignoring all the conspiracy stuff....(most of the below relates to General Aviation, but the wider points about what a transponder is are still valid)

Originally Posted by SUPERMNNN

Transponder signals again:

The altitude 6400 ft and 59 or 5800 ft should be the correct height at the time of the signal was transmitted.

Be aware that there is a difference between "Altitude" and "Height". Altitude is usually with reference to a particular pressure or sea level, height is given with reference to a local pressure setting which describes 0 as at the runway. Look up QNH, QFE, and information on transition altitude and pressure settings to be set above that level.

This is the reason I asked for the transponder, Gary. You do need to have a transponder to get into airport airspace, don't you?

You seem to be confused as to what a transponder does - as you correctly state it gives a controller information about the current position of a particular aircraft - it is interrogated from the ground and the information returned by the transponder.

It's in no way connected to the flight controls. There's nothing to stop you taking off or landing at any airport, airstrip, field or road in the world with or without a transponder.

There's also nothing to stop you flying into controlled airspace with or without a transponder - it may not be legal - but you can certainly do it.

In order to avoid traffic accident, to arrange landing with the ATC, do you need to send in your id and altitude? If an airport doesn't have a control tower, does it mean that there is no ATC?

Not necessarily. Most aircraft have a transponder fitted and should be using it, however not all airfields have ATC and in those cases you are free to land/take off as you see fit as appropriate with the traffic at the airfield at the time. It's the pilots responsibility to maintain separation and to not conflict with any traffic. There's no legal requirement to have a transponder fitted for flights outside controlled airspace (at least in the UK/Europe - however there is legislation in progress to change that).

Also note that not all transponders transmit height/altitude information - that capability is known as Mode C (or mode charlie) and there is a more expansive set of data on new transponders known as Mode S (or mode sierra).

As a pilot, before landing, do you check your tranponder to make sure it is on or not? Can ATC allow you to land without a transponder?

Usually you turn it on before taxing on to the runway (it's usually set to standby once you start up the engine) after you've been assigned a code, and then you leave it on until you land and clear the runway. If anything should happen to it during flight, either the light will stop blinking (if it has one), or ATC will call you up and ask you to "Ident" which means push the button no the transponder which lights up the information for your aircraft on the ATC screen. If it still doesn't work, it'll depend on which class of airspace you're flying in whether you'd want to return to land or not, but it won't stop you controlling the aircraft in the manner you wish.

The code you enter onto the transponder (4 digits) is what the controller uses to match your aircraft up to the information on his screen.

It's possibly to fly without being specifically assigned a code (which is known as a squawk - ie "G-ABCD, Squawk 4321" - means G-ABCD, enter the code 4321 on your transponder. A squawk code is a mandatory readback item and must be read back to the controller by the pilot). You can take off from a farm field in uncontrolled airspace and set your transponder code to a "conspicuity" code. In the UK, this is 7000. It's also referred to as "squawk VFR" when a controller wants you to set that code on the transponder.

ATC can allow you to land without a transponder - they have radar screens which still show the blip (albeit without telemetry) and they have binoculars. At fields without radar, the binoculars (a mark one eyeball ) is the best they have.

Hope that helps - there's loads of information on transponders and the Secondary Survellience Radar system on the net

Perhaps best not to be too explicit in respect of some codes ...

[SUPERMNNN]

Originally Posted by bmoorhouse

Seems to me that SUPERMMM is back on the conspiracy path again. Isn't it time to close this post and advise SUPERMMM to go to his local library to do some basic research on aviation?

All my previous posts have been "moderated" away, so i'll back out of this topic now.

I am doing my research, bmoorhouse. That's how I learned that for the controled space, a transponder is required. I wish I could learn everything in one day and match up with highly educated, experienced pilots.

If you back out now, I would think you either have something to hide or hiding from something, lol (just joking). I need to have real experts to convince me that what I found are wrong! (Yes please forgive my English, my 13 year old son corrects my English all the time.)

Tong Li

[SUPERMNNN]

If you look at this
http://204.108.4.16/d-tpp/0608/05992L24.PDF

and this map:
http://local.live.com/default.aspx?w...nculture=en-US

If you can zoom out on the map, find New Baltimore (on I-76), if you start from here at 7000 ft, where do you go for landing and what's your path? Do you need to go 10nm N.E. of Stoystown and decending to 4500ft then start landing?

[chornedsnorkack]

Originally Posted by Slopey

Ignoring all the conspiracy stuff....(most of the below relates to General Aviation, but the wider points about what a transponder is are still valid)
Be aware that there is a difference between "Altitude" and "Height". Altitude is usually with reference to a particular pressure or sea level, height is given with reference to a local pressure setting which describes 0 as at the runway. Look up QNH, QFE, and information on transition altitude and pressure settings to be set above that level.

Does it mean that e. g. the transponder only knows the altitude (it has no way of knowing what the underlying terrain is or what the local barometric pressure is)?

Originally Posted by Slopey

You seem to be confused as to what a transponder does - as you correctly state it gives a controller information about the current position of a particular aircraft - it is interrogated from the ground and the information returned by the transponder.

So, the transponder does not give the information at all times - it only gives information when/if someone asks for it (and transponder is capable of receiving the request)?

Originally Posted by Slopey

Usually you turn it on before taxing on to the runway (it's usually set to standby once you start up the engine) after you've been assigned a code, and then you leave it on until you land and clear the runway.

In other words, there is a legitimate reason why transponders can be switched off from cockpit - they are not left functioning on parked aircraft - and there do not seem to be any security measures to prevent switching off transponders in flight.

[eastern wiseguy]

Originally Posted by SUPERMNNN

ATC can still see the airplane on their radar, just doesn't have the plane's id, is this correct? If ATC watch it's path, if the plane didn't change direction all of a sudden and there are no other planes nearby, ATC's radar should be able to trace it on the screen. Is this correct?

Tong

If the radar display you are using is a processed system which shows ONLY secondary returns..ie returns from the interrogation of the transponder then aircraft with the transponder OFF or on STANDBY will NOT be seen by it. If the the radar is PRIMARY only then depending on range/height/altitude of the target(aeroplane)and the surrounding terrain it may be shown on the display.


The transponder is based on a standard pressure setting of 1013.25 millibars or 29.92 inches of mercury.and therefore has no idea what the terrain is like underneath it. I will let one of my pilot colleagues discuss EGPWS or Rad Alt with you .Suffice to say ATC don't use those .

[SUPERMNNN]

While leting you guys figure out the landing path, I would like to get back to the engine.

The engine was 300 yards behind the plane on the ground. If it is tumbled on the ground, it should be very easy to find, right at the time it crashed. Tumbling would leave a strong trace on the wooded ground at the crash site.

It was found on 9/13/01, two days after the crash. There are many different versions regarding the distance from the crash site, the longest one is a mile, the shortest is the official version (same as PM article) 300 yard south of the crash site.

The crash crater showed a N.E. direction of impact (plane crashed to the ground flying in the direction of N.E.)

If the engine part, fan, was away from the crash site, couldn'd been explained with ground impact, then it is logical to assume that it was seperated from the plane in the sky. A free fall of engine part would fall behind the plane, because the plane had airlift, could glide further than a piece of metal (1000 lb, according to the government version).

Then we can actually calculate the breaking point, with a given height and speed (assuming the airplane was leveled in the sky, as a first order of approximation).
If we assume that before the crash the plane was at 300 ft, (roughly, according to the eyewitnesses accounts) at 250 mph. The breaking point would be roughly 5.5 seconds before crashing.

Here is how I get the whole thing started.

Then same calculation can be done from the two other isolated debris field, Indian Lake (2.3 miles S.E., New Baltimore, 8 miles S.E. roughly). Ignoring any other noise, fictions, conspiracies, speculations, I want solid physical facts: ground debris. From ground debris to a flying airplane, a simple physics excercise can be done to illustrate the plane's path and roughly the impact time before each isolated debris falled off the plane.

It turned out to be a time consuming exercise. I am sucked into this black hole of "investigation". (someone get me out of here, please!)

Please present counter arguement for the following assumptions:

1. The engine piece was seperated in the air (by either wild handling of the plane or outside impact, the assumption does't speculate anything else, but the seperation of the engine piece).

2. Each isolated debris field was caused by a single "accident" on the plane's flying path, the time of each "accident" can be calculated, given the height and velocity of the plane.

(no conspiracy theories here, the impacts could be terrorist acts or some sort of accident on the plane, we are not speculating anything here, but following the simple physics).

[SUPERMNNN]

Are you all with me so far?

Now let's calculate.
Indian Lake -- 2.3 miles from the crash site.
New Baltimore -- 8 miles from the crash site.

Back track the plane from the crash site:
at 250mph:
above Indian Lake: 33.12 seconds from crashing
above New Baltimore: 115 seconds from crashing

The engine part (fan) left the plane at 5.5 seconds before crashing.

It had to be THREE SEPERATE EVENTS happened to the plane to cause the ISOLATED THREE DEBRIS FIELDS before crashing. It had to be happened in the vicinity of
5.5 seconds before crashing
33 seconds before crashing
115 seconds before crashing

Again, please attack this calculation, prove that I am wrong. No smoking please, such as "I am the expert, I know better". Present your logical, objective, scientific arguement, if not a calculation, please.

By the way, I am still waiting for your flight path. (see #48)

[SUPERMNNN]

I don't think I lost everyone, so far. Do I? This is high school physics.

Ignore how the plane flied, sideways, straight, even doing acrabatics in the sky, we don't care at this point. We know three particular time before crashing now:

5.5 seconds, 33 seconds and 115 seconds, roughly there, plus minus 5 seconds, if the 250mph was correct.

Read the official Voice Recorder Transcript and keep the three time in mind:

http://www.cnn.com/interactive/law/0...t93/index.html

You may want to print this out and use a pen to back track the time from crash, in seconds.

9/11 commission concluded that the crashing time was 10:03:11 am.

Please look at the facts only, do not speculate with imagination, let me know what do you think.

Thank you.

Where is your flight path? (see #48)

[SUPERMNNN]

Where is your flight path? (#48)

Did the two transponder singals, 6400 ft and 5800 ft make any sense? (#41)

The transponder signals are from the following source, provided by a professional air trafic controller:

Tom Brokaw: “You’re keeping your eye on Flight 93 at
this point?”
Stacey Taylor: “Yes. And then the transponder came
back on. We got two hits off the transponder. That’s
something we’ve always wanted to know. Why did the
transponder come back on? Because the hijackers had shut it
off so that they couldn’t be tracked, even though we were
still tracking them. Now we were getting an altitude read
out on the airplane. I can’t remember the precise numbers
but it was around 6,400 feet, and then around 59 or 5,800
feet. And we’re thinking, ‘Oh, you know? Maybe something’s
happened. Maybe this isn’t what we think it is.’”

http://members.fortunecity.com/seismicevent/msnbctransponder.html

[SUPERMNNN]

What's wrong? Am I at the wrong place for the right answers?

Please someone tell me that I am wrong, and explain to me that the two tranponder signals are nonesense.

Should I go to somewhere else for the correct professional opinion?

Here is my personal information, John.
Tong Li, phD.
SuperNova International, Inc.
1709 Thompson St.
Lansing, MI 48906
email: [email protected]

[SUPERMNNN]

You will not be removed provided your posts are acceptable .. basically that requires only that your questions are reasonable and related to aviation technical matters. However, you may well find that some posters may lose interest in the thread at some stage

[xetroV]

Probably best to return to this first (quotes are all from SUPERMNNN, not necessarily in chronological order):

Originally Posted by SUPERMNNN

How hard is it to fly a Boeing 757 with only one engine?

Not hard, provided it's done by a trained pilot. If you loose an engine (or just the engine thrust) the aircraft starts yawing and consequently rolling. This requires immediate corrective action, or else the airplane will spiral down.

If a plane flying at 7000 ft, 500 mph, suddenly lost one engine and decending. How long does it take the plane to drop to 6000 ft, and 5000 ft, comparing to a free fall? (It takes 11 seconds for a free fall to drop 2000 ft. )

Provided the corrective actions are taken: as long as the remaining fuel endurance, and even slightly longer, considering a subsequent glide. A 757 flying on a single engine is perfectly able to maintain altitude, and even climb to a (much) higher altitude, even when fully loaded. (This particular 757 was not fully loaded.)

What if one engine is totally gone (physicall), with less weight on one side, can 757 keep balance and maintain the altitude?

Yes, it can. Provided the fallen engine does not damage the wing's leading edge, it's even easier to fly than with a simple engine failure, since the loss of engine weight and drag counteracts the yawing/rolling effects due to the loss of thrust.

Do you need to turn on the transponder before landing, especially if you were preparing an emergency landing to a small airport?

No. If you are preparing an emergency landing to a small airport, verifying your transponder code is probably the last thing you'll consider. Unless specifically asked to do so by ATC, or if you want to squawk the emergency code.

Do you need the transponder for landing? I mean can you land without the transponder?

No you don't, and yes, you can. Your question is akin to asking: "can you land with your landing lights switched off?".

Of course, ATC may object and local restrictions may prohibit flying without a transponder (or landing lights, for that matter), but in the end it's the pilot who flies the airplane. Can you land on a controlled airfield without a landing clearance? Yes, obviously! Is it allowed? No.

As a pilot, before landing, do you check your tranponder to make sure it is on or not? Can ATC allow you to land without a transponder?

First question: No. Second: Yes. And if they don't you can still land if you want to, knowingly breaking the rules. If a commander thinks it is necessary to break rules in order to ensure the safety of the flight, he is obliged (by law) to do so!

Could you look at this airport and help me to see if 757 can land here?
http://www.airnav.com/airport/2G9

Noone in his right mind would try to land a 757 there, especially with an engine failure (which increases required landing distance by 20-30%; don't know the exact numbers for the 757). The runway is very short, extremely narrow and probably doesn't have the required strength to support a 757. Also, it seems like you shouldn't expect any decent level of rescue and firefighting support there.

Now, one could consider landing on such a airstrip in extreme dire circumstances, e.g. when confronted with a dual engine failure, if there's some kind of uncontrollable fire on board, or in case of severe controllability problems that leave you no other option than to make an emergency landing on terrain. In such circumstances, if you happen to be lucky enough to see this particular airport or if you somehow know about its existence, you could make a visual approach there just trying to survive (note that such small airports are not normally listed in navigation databases in the FMS, nor will there be any approach charts available on board), as any runway is better than none.

In case of a single engine failure or engine separation, any professional pilot would first stabilize the situation, and thereafter plan for a proper diversion and approach to a suitable airport. In that case there's no reason whatsoever to make a mad rush to the nearest visible airstrip.

The airport I showed you is an airport 6 miles west (a little bit north) of the crash site, Somerset County Airport. The runway direction is that you have to land from N.E to S.W, I believe.

Or vice versa, from S.W. to N.E., depending on the wind direction.

... If the wind blow light debris 8 miles south ...

In that example, with a wind blowing from North to South, the landing runway on that airfield would be 06: from S.W. to N.E.

... Then add the fact that there were one professional commercial pilot on flight 93 and an air traffic controler as passengers.

I don't know the specifics about United Flight 93, but assuming that these two individuals would have succeeded in taking over the controls, they would have acted as outlined above: fly the airplane, reconfigure to sort out any non-normal system behaviour and stabilize the situation, and then plan and execute a proper diversion to a suitable airport. Only in extreme emergencies a diversion to this little airfield would be considered, and then it could indeed be helpful to have a controller who might know of its existence sitting in the cockpit.

Even if the transponder switched on by itself, or some kind of malfunction. It must gave out ID signal and altitude, so the control center could spotted it. The altitude 6400 ft and 59 or 5800 ft should be the correct height at the time of the signal was transmitted.

Well, if you indeed consider "some kind of malfunction" then there's no reason to assume that the altitude (not height, this is a pressure-related signal!) information received by ATC is necessarily true. I don't see any reason why it shouldn't in this particular case, but in general you can't entirely rule out transponder malfunctions. Also, garbage in = garbage out: if the pressure signal used by the transponder is incorrect then the altitude read-out on the ATC scope will be incorrect, as illustrated by the crash of AeroPeru 603. Those ATC-reported altitudes should be correct, but there's still a very remote possibility that they aren't.


Just clearing up some apparant misunderstandings about flight operations here. I'll leave it at that, because reconstructing conspiracies (real or not) is not exactly my cup of tea.

[SUPERMNNN]

Thanks alot, xetroV, this clears up a lot of my questions, thank you for your time.

[SUPERMNNN]

As I understand, please bear with me,

1. The sudden turn of the airplane from towards Washington DC to towards Indian Lake was not possiblly related to the Sommerset County airport, unless it was an emergency, such as uncontrollable fire on board.

2. The transponder signals were more likely accidental, not related to the airplane landing into an airport. It was most likely not pilot related, i.e. indicating that if our pilot was in control or not.

3. No professional pilot and air traffic controller would plan ahead, thinking of landing a 757 into this small airport.

Great, please be patient with me, as a guy who is not in the field of aviation, I need this type of detailed answers. Thanks again, xetrov.

Considering that at 10:00, the plane was at an altitude of 7500, the plane crashed (to the altitude of 0) at 10:03:11, then if the two signals were between 10:00 and 10:03, 6400 ft and 5800 ft,most likely the tansponder gave the correct altitude reading, obviously it did give the correct flight number, therefore we can assume that the transponder was functioning but most likely switched on by none human activities, "unless specifically asked to do so by ATC, or if you want to squawk the emergency code."

Does the ATC normally ask you for transponder signals before landing, especially for emergency landing?

Is it possible for our pilot to use the tansponder to inform the ground that "we are in control"? It seems to me, from Tom Brokaw's interview, that it was a pretty loud signal to the controller. It might not be a big deal for a regular flight or emergency.

[SUPERMNNN]

Am I right to assume that three seperate debris fields indicating THREE DIFFERENT EVENTS while the plane was in the sky?

While considering a normal flying speed for the low altitude, such as 250 knots? As a none professional, ignoring the difference between air speed and ground speed, for arguement sake, I used 250mph and obtained three time: 33 seconds -- above indian lake, 115 seconds above New Baltimore, 5.5 seconds -- seperation of the engine part.
(For any accident, numbers make much more sense to me than imaginations.)

It might be possible that the seperation of the engine and debris in Indian lake 5.5 seconds to 33 seconds were cause by a single event, if the engine was seperated in a later time. But definitely the debris found in New Baltimore was a seperate event. The two events were 82 seconds apart. Even if the plane flied at twice of the speed, 41 seconds was a long time seperation. Therefore two seperate events caused the isolated two different debris field, Indiana Lake and New Baltimore.

Is there any problem with this analysis?