|Quoting NAV30 (Reply 236):|
Except - on the basis of 'zero' information, how did the investigators manage to come up with all this 'turn north-west, turn south-west, turn south' stuff?
, for your sake, let's recap over 60 threads on this topic:
1. They knew the aircraft made it as far as IGARI. Independent ADS
-B data also covered that.
2. They knew the aircraft went past IGARI. Independent ADS
-B data also covered that.
3. They knew the aircraft went missing not long after IGARI after its transponders went off.
4. They picked up on primary radar (which does not need a working transponder on the aircraft), which they suspect was MH370 making a turn towards Malaysia.
5. They put together all possible primary radar detection they had on what could have been that aircraft.
6. That aircraft they suspected was MH370 was tracked going back towards Kota Bharu, then to Penang area, before turning north west, to the limit of the primary radar coverage.
7. They did not immediately confirm the phantom aircraft as MH370, search continues to the north east of IGARI.
8. Inmarsat then revealed the aircraft was flying until over 8am, based on the satellite pings to the aircraft's satcom antenna.
9. Based on the pings going through which satellite, it was easy to confirm that the aircraft did not continue north east (it would have been handed off to another Inmarsat-3 satellite).
10. Once the pings were revealed to the authorities by Inmarsat, the Malaysian government put the information together with the phantom aircraft that went west that they suspected was MH370, and concluded that it was indeed MH370.
11. The Ping Data initially did not reveal that it ended up northwest or southwest or south, it only revealed that it ended up somewhere along a radius circle, which when you combine it with the aircraft's endurance circle out of what was then known of the aircraft, showed it went as far north west as Azerbaijan OR
it went somewhere in the Indian Ocean. Up to this point, only the turn back over Malaysia then turn northwest can be ascertained.
12. The Ping Data records were then linked to records of the satellite transmissions, to which they got the frequencies which the satellite received from the aircraft, these are somewhere near the expected receiving frequency (pre-allocated upon initial contact, and adjusted by the aircraft so that the satellite doesn't receive out of frequency transmissions due to the aircraft's movements). The aircraft compensates the doppler effect of the aircraft's movement to a fixed satellite position, but the satellite itself is not stationary and has it's own little wobble orbit along it's allocated geo-stationary orbital slot.
13. Based on the wobble, they now have a method to discriminate whether the aircraft was south or north of the equator, by comparing the satelite's receiving frequency offset which cannot be adjusted by the aircraft antenna, with other aircraft communicating with that satellite along the same / similar times, and with the predicted models, from there, they concluded that the MH370 was south of the equator when the last satellite ping was made.
14. The last civilian radar plot shows the aircraft north east of Malaysia going east, then the military radar followed this aircraft over Malaysia towards Penang area which then turned north west, until it disappeared... and with the satellite communications data, it is indicated that it ended up quite far south. So therefore, put all of them together, you get the 'turn north-west, turn south-west, turn south' stuff
|Quoting NAV30 (Reply 240):|
None of us can 'have it both ways,' DavidL. If none of the ATC guys knew where the aeroplane was, no-one ELSE can know where it went?
1. The aircraft disappearing from secondary radar = something's wrong. You don't need to know where it went to conclude something was wrong (as per David's post).
2. ATC in Vietnam didn't establish contact with the aircraft as per the normal flow, they checked with Malaysian ATC to see whether or not it was handed off or whether it returned... the Vietnamese ATC, suspected something was wrong. Malaysian ATC's answer, confirmed that something was wrong. No need to know where the aircraft went to see something was wrong.
3. The military saw something but they did not know it was MH370, so no one for sure knew where MH370 went after it disappeared from civilian radar that night, and not until sometime later after they looked at all the plots and then got the satcom ping info that they can conclude 'with enough confidence' (so to speak) that what the military saw on radar was MH370.
This is not "having it both ways"... And no, a 777 isn't a stealth fighter either... so if it disappears from civilian secondary radar, and is within military primary radar coverage, someone watching the primary radar can still see the aircraft.
|Quoting jetsetter1969 (Reply 242):|
Would it be feasible to fit a GPS tracking device with uninterupted power supply to all civil aircraft so they can be tracked if such an incident occurred again?
We've been through this a lot in the past threads on this topic.
tracking with position transmission through satcom does exist.
If you want to make it not able to be switched off, sorry... ain't gonna happen. You need to be able to switch it off in one way or another. However, you can, like satcom, make it a stable system where the circuit breaker does not have to be in the cockpit, making it impractical for you to switch it off quickly and discreetly if you want to steal an aircraft with a couple of hundred passengers.
If you insist it must not be able to be switched off, sorry, I need to show you the door...
We don't change aviation safety by knee-jerk reactions.