Malaysian Airlines MH370 contact lost
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Are there any good ideas as to why this misunderstanding about 4 hours of ACARS data could arise? Is there some system in the middle, such as the airline's server or the satellite account logs or anything like that, which could show what looked like activity from the aircraft even though the aircraft did not send data?
Very trivial example: I can die at 4 o'clock and two hours later someone can see an ad on Facebook with my name being listed as "OlaM likes Boeing 777s" time stamped 6 o'clock- it seems like an act done by me after death, but it's really done by a computer.
Less trivial example: You purchase something on your credit card March 8. You die on March 9. Your statement says you paid for it March 10. Bought by a ghost? No, March 10 was the first business day after Saturday the 8th.
It seems this case is plagued by random statements made by ill-informed or misunderstanding personnel to crazed reporters and the hurtful conspiracy effects will linger for a long time. So what about ACARS can be misunderstood in a way that makes you think the plane flew 4 hours longer than it did?
Very trivial example: I can die at 4 o'clock and two hours later someone can see an ad on Facebook with my name being listed as "OlaM likes Boeing 777s" time stamped 6 o'clock- it seems like an act done by me after death, but it's really done by a computer.
Less trivial example: You purchase something on your credit card March 8. You die on March 9. Your statement says you paid for it March 10. Bought by a ghost? No, March 10 was the first business day after Saturday the 8th.
It seems this case is plagued by random statements made by ill-informed or misunderstanding personnel to crazed reporters and the hurtful conspiracy effects will linger for a long time. So what about ACARS can be misunderstood in a way that makes you think the plane flew 4 hours longer than it did?
We don't have to buy it, nor believe it, but it's there.
ACARS Data
@CommanderCYYZ
Others have addressed your question a few times, but to recap: the satellite radio system "pings" the satellites to maintain contact even without sending otherwise useful data. So, by saying in effect "Here I am, are you there?" repeatedly, the system is ready, the satellite is known, etc., for when real data communication is needed.
So the reports that no additional engine data was sent can be true, along with the 4-5 hours of "pings".
Others have addressed your question a few times, but to recap: the satellite radio system "pings" the satellites to maintain contact even without sending otherwise useful data. So, by saying in effect "Here I am, are you there?" repeatedly, the system is ready, the satellite is known, etc., for when real data communication is needed.
So the reports that no additional engine data was sent can be true, along with the 4-5 hours of "pings".
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@Olam
The thing is, there was no data TX'd. What appears to be the case, according to reports, was that ACARS system on the AC was sending RTS pings periodically but never connected. The reason given was that MAS don't pay for that level of monitoring, so it was reported. However, the "pings" would seem to suggest that the AC was still alive 4 hrs after contact was lost.
Boeing said that no data was received from the AC after contact was lost.
RR has said the no data was received after contact was lost.
RR has said the no data was received after contact was lost.
BTW, passenger oxygen is good for ~15 minutes. Crew oxygen somewhat longer than that.
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What benefit is it to the investigators to publish what the cargo was? - None, so they won't publish it.
Sat coms, 4 hours
Here are what now seem to be almost facts.
The ACARS system for the airframe did not have a satellite subscription.
The ACARS system for the engines did have a satellite subscription.
The satellite path is used when there is no VHF path available.
The engine ACARS only sends when a significant event takes place. There was no event after the top of climb and so no further messages were sent.
The Engine ACARS satellite coms system "pings" the satellite every 30 mins.
Therefore:- Since about 8 pings were received and logged the engines ran for a further 4 hours after last message at top of climb since a shutdown would have resulted in an ACARS message. The exact time is not known of course.
By the way. I am far from satisfied that the satellite system used is Iridium. Due to the low earth orbit and rapidly changing overhead satellites I would have thought that the ping might need to be more frequent.
The ACARS system for the airframe did not have a satellite subscription.
The ACARS system for the engines did have a satellite subscription.
The satellite path is used when there is no VHF path available.
The engine ACARS only sends when a significant event takes place. There was no event after the top of climb and so no further messages were sent.
The Engine ACARS satellite coms system "pings" the satellite every 30 mins.
Therefore:- Since about 8 pings were received and logged the engines ran for a further 4 hours after last message at top of climb since a shutdown would have resulted in an ACARS message. The exact time is not known of course.
By the way. I am far from satisfied that the satellite system used is Iridium. Due to the low earth orbit and rapidly changing overhead satellites I would have thought that the ping might need to be more frequent.
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Mandatory GPS Tracking
General aviation aircraft have been doing this for years. I know of at least 3 vendors who offer such service at modest cost: Spidertracks, Spot, and InReach.
Basically, a unit on the a/c sends its GPS coordinates every 10 minutes or to so a satellite which relays it to the tracking company's servers.
The airborne unit often goes on the glareshield, and it includes its own battery that lasts for a few hours if power is lost.
Basically, a unit on the a/c sends its GPS coordinates every 10 minutes or to so a satellite which relays it to the tracking company's servers.
The airborne unit often goes on the glareshield, and it includes its own battery that lasts for a few hours if power is lost.
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Well, since a lot of people here doesn't seem to understand what's going on regarding the ACARS/SATCOM stories in the press, let's recap what's going on regarding the new information from the US.
- MAS ACARS comms only work thru VHF since they chose not to pay for the extra fee for ACARS SATCOM link
- That 777-200 is SATCOM equipped
- What was found by US Government services (NSA, or maybe they asked Iridium directly to check the logs) is that, since the a/c ACARS system was out of VHF coverage, the system tried to connect thru SATCOM. But since MAS doesn't have a contract for that, connection was rejected, but remains a trace in their logs.
- That means that what they actually found is the log indicating every time the aircraft ACARS system tried to log in thru SATCOM and failed due to the lack of contract for that. Since the ACARS system onboard that specific aircraft tried for 4 hours after its disappearance to connect via SATCOM to the ACARS network, it means the aircraft was, at least, powered on and, since not found anywhere yet, probably flying.
Sorry if I wasn't clear enough, I tried to write everything down ASAP...
I have an IT background, and according to all the available sources, this is my interpretation of what's going on.
- MAS ACARS comms only work thru VHF since they chose not to pay for the extra fee for ACARS SATCOM link
- That 777-200 is SATCOM equipped
- What was found by US Government services (NSA, or maybe they asked Iridium directly to check the logs) is that, since the a/c ACARS system was out of VHF coverage, the system tried to connect thru SATCOM. But since MAS doesn't have a contract for that, connection was rejected, but remains a trace in their logs.
- That means that what they actually found is the log indicating every time the aircraft ACARS system tried to log in thru SATCOM and failed due to the lack of contract for that. Since the ACARS system onboard that specific aircraft tried for 4 hours after its disappearance to connect via SATCOM to the ACARS network, it means the aircraft was, at least, powered on and, since not found anywhere yet, probably flying.
Sorry if I wasn't clear enough, I tried to write everything down ASAP...
I have an IT background, and according to all the available sources, this is my interpretation of what's going on.
Last edited by opsmarco; 13th Mar 2014 at 23:44. Reason: Clarification
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Agreed, and I believe the official line at today's press conference was to say that reports to the contrary were "inaccurate", not that they were wholly wrong. Hence (my deduction) the interest now in the Indian Ocean.
Malaysia Airliner Communications Shut Down Separately: US Officials Say - ABC News
The above statement would normally be taken as fact. But to date, almost every similar (definitive) statement has been discounted.
Enough of the secret squirrel stuff. We seem to have several statements from sources that usually are reliable being refuted everytime by the Malaysians leading to this never ending merry-go-round.
Now, if the Malaysians are correct, why are these sources intent on providing mis-information?
Again, sources that you would normally associate with being reputable.
"We have an indication the plane went down in the Indian Ocean," the senior Pentagon official said.
Enough of the secret squirrel stuff. We seem to have several statements from sources that usually are reliable being refuted everytime by the Malaysians leading to this never ending merry-go-round.
Now, if the Malaysians are correct, why are these sources intent on providing mis-information?
Again, sources that you would normally associate with being reputable.
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Well, since a lot of people here doesn't seem to understand what's going on regarding the ACARS/SATCOM stories in the press, let's recap what's going on regarding the new information from the US.
- MAS ACARS comms only work thru VHF since they chose not to pay for the extra fee for ACARS SATCOM link
- That 777-200 is SATCOM equipped
- What was found by US Government services (NSA, or maybe they asked Iridium directly to check the logs) is that, since the a/c ACARS system was out of VHF coverage, the system tried to connect thru SATCOM. But since MAS doesn't have a contract for that, connection was rejected, but remains a trace in their logs.
- That means that what they actually found is the log indicating every time the aircraft ACARS system tried to log in thru SATCOM and failed due to the lack of contract for that. Since the ACARS system onboard that specific aircraft tried for 4 hours after its disappearance to connect via SATCOM to the ACARS network, it means the aircraft was, at least, powered on and, since not found anywhere yet, probably flying.
- MAS ACARS comms only work thru VHF since they chose not to pay for the extra fee for ACARS SATCOM link
- That 777-200 is SATCOM equipped
- What was found by US Government services (NSA, or maybe they asked Iridium directly to check the logs) is that, since the a/c ACARS system was out of VHF coverage, the system tried to connect thru SATCOM. But since MAS doesn't have a contract for that, connection was rejected, but remains a trace in their logs.
- That means that what they actually found is the log indicating every time the aircraft ACARS system tried to log in thru SATCOM and failed due to the lack of contract for that. Since the ACARS system onboard that specific aircraft tried for 4 hours after its disappearance to connect via SATCOM to the ACARS network, it means the aircraft was, at least, powered on and, since not found anywhere yet, probably flying.
It is possible that NSA satellites detected the VHF pings by the ACARS/RR systems, not any attempted satellite pings.
Your summary assumes the pings were for satellites rather than VHF ground stations.
You may be right, but it seems to make more sense for it to have taken this long because NSA needed to sort through many, many radio events rather than just look at satellite logs.
YMMV.
What really puzzles me its the Myanmar Theory...i've been there, as well some friends presently working based there, and its not anymore the typical "007" country movie with vast jungles full of places where u can build a new rwy, or already use an old one constructed, without being noticed. Even if we can land and stop it in 1300 mts, the handling to support it and after that hidding it among the jungle its not a so easy task, more naive and "Hollywoodesque" than all the rest, me thinks.
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"since the a/c ACARS system was out of VHF coverage, the system tried to connect thru SATCOM"
Are you sure it only tries to ping/connect if out of VHF Range ..?
...I thought I had read that it pings the SATCOM all the time.
Are you sure it only tries to ping/connect if out of VHF Range ..?
...I thought I had read that it pings the SATCOM all the time.
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Thanks opsmarco! I trust that is based on practical experience with how ACARS hardware and satcom accounts are handled. If so, it begs another question, how much hardware can survive an ocean impact and still transmit?
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- What was found by US Government services (NSA, or maybe they asked Iridium directly to check the logs) is that, since the a/c ACARS system was out of VHF coverage, the system tried to connect thru SATCOM. But since MAS doesn't have a contract for that, connection was rejected, but remains a trace in their logs.
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too soon to discount foul play
Civil Aviation Chief Azharuddin “There are some things that I can tell you and some things that I can’t.”
Federal CID director Comm Datuk Hadi Ho Abdullah "The police will divulge the latest development in the case at the right time"
Minister in the Prime Minister’s Department Datuk Seri Shahidan Kassim confirmed that he will be flying to an undisclosed location “You will have to wait for the official announcement”
Unnamed Chinese govt official "Malaysian authorities are deliberately concealing information"
>
Given evidence emerging of at least two changes of heading after the comms black out and engines running for sometime, it is too early to rule out darker explanations IMV...
Federal CID director Comm Datuk Hadi Ho Abdullah "The police will divulge the latest development in the case at the right time"
Minister in the Prime Minister’s Department Datuk Seri Shahidan Kassim confirmed that he will be flying to an undisclosed location “You will have to wait for the official announcement”
Unnamed Chinese govt official "Malaysian authorities are deliberately concealing information"
>
Given evidence emerging of at least two changes of heading after the comms black out and engines running for sometime, it is too early to rule out darker explanations IMV...
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@CommanderCYYZ
On the balance of probabilities, the ACARS had been disabled, but the SatCom system was alive and handshaking periodically with a selected satellite.
What appears to be the case, according to reports, was that ACARS system on the AC was sending RTS pings
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flt001
Not that strange : the same happens if you place an old, inactive sim card in a mobile phone. Your phone will keep trying again and again to connect to the network, despite previous rejections. Same with a router at home, once you resigned your internet connection : machines will try again and again to connect, since the error can be due to a temporary problem in the network.
Regarding specifically the ACARS system, I suppose there's a way, thru maintenance pages, to change that, but only a certified 777 engineer will be able to confirm that.
Regarding specifically the ACARS system, I suppose there's a way, thru maintenance pages, to change that, but only a certified 777 engineer will be able to confirm that.
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I find it very hard to believe that the ACARS system on Malaysia aircraft do not have SAT connectivity.
What is most likely is that MAS does not subscribe (pay) for airframe status monitoring. That requires a lot of bandwidth that they've determined are not worth the extra cost.
OOOI/weather/free text are probably all available to the pilots when the ACARS is using the VHF *and* SAT medium. Additionally, the RR health monitoring is probably paid for by RR and/or MAS as part of the purchase/warranty programme and does transmit via satellite, but only when programmed or demanded.
Snapshots of engine parameters are taken and sent at pre-programmed intervals or whenever something is out of tolerance. What that programming is is known to the engineers.
What the WSJ got wrong was that the Inmarsat network detected "pinging" from the Satcom system itself, not the RR trend monitoring data.
What is most likely is that MAS does not subscribe (pay) for airframe status monitoring. That requires a lot of bandwidth that they've determined are not worth the extra cost.
OOOI/weather/free text are probably all available to the pilots when the ACARS is using the VHF *and* SAT medium. Additionally, the RR health monitoring is probably paid for by RR and/or MAS as part of the purchase/warranty programme and does transmit via satellite, but only when programmed or demanded.
Snapshots of engine parameters are taken and sent at pre-programmed intervals or whenever something is out of tolerance. What that programming is is known to the engineers.
What the WSJ got wrong was that the Inmarsat network detected "pinging" from the Satcom system itself, not the RR trend monitoring data.
