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Originally posted by ProudBird
reply to post by TrueAmerican
NO, this is the feeble claim by someone who blog posted as "Woody Box", and now (some years later I might add) has been picked up by the "P4T" in order to drum up attention, and "donations:.
The ARINC system attempted to send the message from Dispatch, and used the algorithm to ascertain where the flight would have been along its normal original Flight Plan routing.
Period.
Full stop.
For aircraft in flight, the CPS holds the RGS station information as active for only 11 minutes. After that time, the station information is deleted because an en route aircraft will usually have moved on to a different set of stations. When an aircraft uses 10-minute tracker messages, CPS is continuously refreshed with new RGS information and always knows where to deliver an uplink message.
In a Category B network, aircraft must monitor all the stations available and then select a single station to establish a connection to the ground. During the connection process, the first action of the avionics is to send a Link Test to establish a connection with the RGS. This Link Test has a format that is identical to the Category A tracker message. Once the connection is established, messages to the aircraft are handled by this single RGS. With Category B, the aircraft can only connect to one RGS at a time; therefore, during flight the avionics must change RGS connections and repeat the connection process every few minutes. As a result, while the traditional tracker function is not needed, Link Test messages are still transmitted at frequencies that are at least the same or greater than those used in a Category A network.
There is no dispatcher, no ACARS engineer, no ARINC professional, no ARINC or Boeing official document, no pilot that will ever confirm your claim. ACARS are not sent based on the flight plan. Period. Please resign to this fact. Even gman, even LaBTop (if you bothered to read their posts) clearly stated that uplinks are sent based on the aircraft's positional data, i.e. based on the media advisory messages that the aircraft itself constantly sends to the closest remote ground station.
If ACARS were sent based on the flight plan, as you claim, most of messages would be lost every day for the simple reason that thousands of aircraft are rerouted daily because of multiple causes, such as weather, traffic, airport congestion etc.
Why don't you start taking a look at the "The Global Link", 7/2002, the newsletter from ARINC, where Category A and Category B Flight Tracking is clearly explained with a language accessible also to the layman?
ProudBird, with all means of respect. It's time you to stop squawking misinformation only based on your bias and your desire to defame other people whose only crime is supporting theories different than yours.
Google Video Link |
Originally posted by ProudBird
reply to post by bubs49
Again, perfectly mistaking my posts, because I cannot each time be PRECISE in every aspect of what is written.....those who know the facts, and understand, are not fooled by these tactics.
Originally posted by ProudBird
Yeah, more typical BS. I noted there were no specific citations (another well-known tactic), but instead a blanket exhortation to "Read This!", with the oh-so-subtly implied insult.
Originally posted by ProudBird
Those who are claimed (oh, Boo-Hoo, cry us a river why dontcha?) to be "defamed" are thoroughly deserving of derision and scorn, because of the obvious (to those of us who are experienced in the fields we're discussing)
6 The Global Link • July 2002
THE USE OF TRACKER MESSAGES IN CATEGORY A ACARS NETWORKS
T E C H N O TA L K
Many customers frequently ask about the purpose of tracker messages: “What are tracker messages?” “How are tracker messages used?” This article provides answers to those questions.
Description and Purpose of Tracker Messages
Tracker messages are VHF ACARS downlinks that are sent automatically at fixed intervals, typically 10 minutes. These messages allow the service provider to dynamically track aircraft during flight. In most cases, the avionics use a Q0-labeled Link Test as a tracker message.
The Link Test message does not contain any useful application text; therefore, it does not result in a delivery message to the airline customer. Some customers prefer a user-defined tracker message with a message label other than Q0. The message may include additional information such as geographic position or altitude within the message text. These user-defined messages certainly would be delivered to the airline host computer.
As mentioned, tracker messages are used for flight following. Each time a downlink message is received from an aircraft, the ARINC ACARS Central Processor System (CPS) is updated with the three best remote ground stations (RGSs) that received the downlink message. When ARINC receives an uplink message from the airline computer, it first consults a table in CPS to determine which stations are most likely in contact with the aircraft. It tries these stations for message delivery. If no downlink activity has been heard from the aircraft in 11 minutes, the CPS system returns the uplink back to the originator as undeliverable.
For aircraft in flight, the CPS holds the RGS station information as active for only 11 minutes. After that time, the station information is deleted because an en route aircraft will usually have moved on to a different set of stations. When an aircraft uses 10-minute tracker messages, CPS is continuously refreshed with new RGS information and always knows where to deliver an uplink message. If an airline sends uplink messages only after they have been specifically requested by a downlink from the aircraft, then tracker messages may not be needed. This is because the preceding downlink request automatically updates the ground network with aircraft location information. An uplink message that was not first requested by the aircraft (by downlink) is referred to as an “unsolicited uplink.” For unsolicited uplinks, CPS knowledge of the best RGSs is essential to successful delivery of the message. In practice, almost all airlines send some unsolicited uplinks and depend on the service provider to know what RGSs are in communication with the aircraft.
Category B Networks
and Tracker Messages
In a Category B network, the traditional tracker message is considered optional because the tracker message function is covered elsewhere in the air/ground protocol. This would lead some to believe that a Category B network operates more efficiently by not using traditional trackers. In a Category B network, aircraft must monitor all the stations available and then select a single station to establish a connection to the ground. During the connection process, the first action of the avionics is to send a Link Test to establish a connection with the RGS. This Link Test has a format that is identical to the Category A tracker message.
Once the connection is established, messages to the aircraft are handled by this single RGS. With Category B, the aircraft can only connect to one RGS at a time; therefore, during flight the avionics must change RGS connections and repeat the connection process every few minutes. As a result, while the traditional tracker function is not needed, Link Test messages are still transmitted at frequencies that are at least the same or greater than those used in a Category A network.
Summary
Tracker messages allow ARINC’s Category A VHF network to track an aircraft during flight and allow us to make the best RGS selections for message delivery. Tracker messages do not decrease the network efficiency and are recommended for customers that send unsolicited uplink messages. Many avionics systems allow an airline to enable tracker messages as a maintenance or configuration item. As always, please contact us if you’d like further information or assistance in enabling tracker messages in your aircraft.
Steve Leger
[email protected]
tel +1 410 266 2169
fax +1 410 266 4499
"As always, please contact us if you’d like further information or assistance in enabling tracker messages in your aircraft."
ProudBird :The ARINC system attempted to send the message from Dispatch, and used the algorithm to ascertain where the flight would have been along its normal original Flight Plan routing. Period. Full stop.
Bubs49 : ProudBird, with all means of respect. It's time you to stop squawking misinformation only based on your bias and your desire to defame other people whose only crime is supporting theories different than yours. There is no dispatcher, no ACARS engineer, no ARINC professional, no ARINC or Boeing official document, no pilot that will ever confirm your claim. ACARS are not sent based on the flight plan. Period. Please resign to this fact. Even gman, even LaBTop (if you bothered to read their posts) clearly stated that uplinks are sent based on the aircraft's positional data, i.e. based on the media advisory messages that the aircraft itself constantly sends to the closest remote ground station. This is why the CPS always chooses the best RGS to route an uplink and reach the targeted aircraft. ACARS is no guessing game. Ask any ACARS expert and you'll get the same answer: until an aircraft drops its positional data, there is no way for the CPS or for the airline to know exactly where the aircraft is. If ACARS were sent based on the flight plan, as you claim, most of messages would be lost every day for the simple reason that thousands of aircraft are rerouted daily because of multiple causes, such as weather, traffic, airport congestion etc.
Originally posted by LaBTop
reply to post by bubs49
Only after the next 10 minutes period, in the 11th minute, does the dispatcher, the CPS or the airline know exactly where the plane was AT THAT EXACT MOMENT of sending its LAST positional data.
It will already have flown further in the next seconds/minutes, that's why they need an algorithm to calculate possible positions in the NEXT 10 minutes, to compare it with their list of available ground stations, and use the probable nearest one to the already further advanced plane's position.
Originally posted by LaBTop
And, Bubs49, we all know that those 2 planes (UAL93 and 175) we talk about here, were already HIJACKED and steered far away from their original flight plan. Thus, the CPS was already a long time in "guessing mode". Calculating based on the former 10 minutes periodS, where the plane COULD be in the next 10 minutes.
Originally posted by LaBTop
And that's why those last ACARS text messages got REJECTED, 11 minutes LATER.
That's 660 seconds LATER.
All your crap about those other ACARS messages received in other stations further away from the crash site, are ATTEMPTS to connect to that already CRASHED plane. And since the last/next 10 minutes positional data stream was not received YET, they all were neatly timestamped. Which does not AT ALL indicate that they were received in that already totally wrecked plane.
Until those last 10 minutes ticked away its last second, THEN all other NEXT in row ACARS messages were bounced/rejected with NO timestamp and that ***text*** last line on their print-outs.
So, in that preceding LAST 10 minutes/660 seconds period, nearly all ACARS messages were not received too.
You can calculate that if you find those two last 10 minutes timestamps from the positional data stream sent to CPS. Then accept a time for the crash, and you know exactly which last ACARS message ATTEMPTS have failed to reach a not flying plane anymore.
Originally posted by bubs49
When a poster from UM contacted an ARINC professional to ask how could an uplink sent at 9:23 to United 175 be routed through PIT when the aircraft had officially crashed at 9:03 in New York, the answer was: "No, this is impossible".
For the records, I continue posting here only for the benefit of those (like True American) who appear to be open to understand. Your bias is so strong that no evidence will ever be enough for you to change your mind.
Originally posted by bubs49
When a poster from UM contacted an ARINC professional to ask how could an uplink sent at 9:23 to United 175 be routed through PIT when the aircraft had officially crashed at 9:03 in New York, the answer was: "No, this is impossible".
Bubs49 : No matter how the ARINC algorithm works (and I proved it does not work the way you claim), after 20 minutes from the alleged crash we should expect a rejected format and not a message with two timestamps, as for every ACARS which is normally received by an aircraft.
Originally posted by snowcrash911
But it will probably take another six years of fruitless discussion to conclude, especially since P4T will make sure
all experts will be unavailable for comment due to their usual 'scorched earth' strategy.
Originally posted by snowcrash911
As I've said above, I think tracker messaging may not have been installed on UA 175.
Originally posted by snowcrash911
Anyways, all this is pretty simple. Since flight plan predictive logic is incorporated into routing mechanisms alongside other variables, the ground stations selected are along the flight plan.
Originally posted by LaBTop
If you are a 2001 ARINC expert, you can answer all that. Like this man surely is :
Steve Leger
[email protected]
tel +1 410 266 2169
fax +1 410 266 4499
You will be able to read back from him, what any combination of characters in those two specific 1323 (the sent) and 1420 (the rejected) messages you showed us, will mean.
Any one, send him an email. No, I definitely won't, for my own privacy reasons.
I expect you to learn that certain characters indicate where the message is sent, if it got a return message, if it got received by the ARINC headquarters, if that one did sent it to the calculated ground station and if that one attempted to uplink it to the plane.
Originally posted by snowcrash911
Anyways, all this is pretty simple. Since flight plan predictive logic is incorporated into routing mechanisms alongside other variables, the ground stations selected are along the flight plan.
Bubs49 : So I guess you won't have any problem to link any source, document, expert advice or whatever to support this claim, right?
Moreover, let me ask you one simple question. If "the ground stations selected are along the flight plan" (your own words), how on earth ACARS can reach an aircraft whenever it is rerouted (what happens on a daily basis for multiple reasons)?
Bubs49 : Anyway, Ballinger already provided a clear, straightforward, unquestionable explanation about what first and second timestamp mean: "Mr. Ballinger stated that the ACARS messages have two times listed: the time sent and the time received". In my opinion this needs no further clarification, but of course feel free to contact United Airlines for more information.
However, until receiving the above time sequence from Commission staff,
Ballinger had calculated that there had been a 20-minute (rather than a 10-minute)
lag in his receipt of the information on the flight attendant's call, and so he was
somewhat less sure of what the result would have been. Mr. Ballinger stated
however that it was the crash of 1'75 into the WTC at 9:03, not the concern that it
had been hijacked that prompted him to send the ACARS messages warning of
cockpit intrusion. [NOTE: Staff does not presently have decisive evidence as to
the source of the delay in transmission of information about the 8:52 a.m. call
from the San Francisco office to United headquarters in Chicago.
UAL headquarters staff recalled getting the call.from San Francisco around 9:00 a.m.
and San Francisco personnel could not place the precise time of their call to
Chicago.]
[U] Immediately after receipt of the report from "xxxxx", Ballinger sent an
ACARS message to Flight 175 at 9:03, inquiring "How is the ride. Any thing
dispatch can do for you." At the time, Ballinger was not aware of"xxxxx"
simultaneous ACARS message to Flight 175 : "NY approach looking for ya on
127.4." However, Ballinger believes it was perfectly correct for "xxxxx" to proceed in this manner because it is customary for dispatchers to help each other out in times of emergency. Mr. Ballinger stated that he received no response from Flight 175 to his message
U]Ballinger learned of the 8:59 a.m. ACARS message from "xxxxx" in
United's San Francisco office to Flight #175 sometime between the second and
third crashes on 9/11 (between 9:03 and 9:38 a.m.)