BACLightning
15th Mar 2015, 13:50
Having reviewed the Factual Information (http://mh370.mot.gov.my/), rather a few questions arise that some of you actual pilots, radar operators and aero electrical engineer types might be able to answer :)
Apologies for any questions that have been done to death on here already.
'Abrupt' disappearance
At page 3 the report states:
"The tracking by the Military continued as the radar return was observed to be heading towards waypoint MEKAR, a waypoint on Airways N571 when it disappeared abruptly at 1822:12 UTC [0222:12 MYT],10 nautical miles (Nm) after waypoint MEKAR."
Bolding is mine - while this is almost certainly meaningless, this seems an emotive choice of words, perhaps? Is it usual for primary returns to disappear 'abruptly' if an aircraft is proceeding out of radar coverage in straight and level flight? If not, aside from an event which disintegrated the airframe, is there any course of action that is likely to result in such an 'abrupt' disappearance? I am assuming that radar coverage is poor at distance and closer to the land or sea (hence the military practice of 'terrain masking') - would a widebody rapidly descending towards the outer limits of radar coverage be more likely to deliver such an 'abrupt' disappearance, and would it be apparent that such a manoeuver was being carried out prior to that point?
SATCOM link lost, lack of Flight ID and no further ACARS on subsequent Log-on
As I understand it, Flight ID for GES logon is provided by the aircraft's AIMS units (of which there are two - page 49). These also provide ACARS reporting.
After the SATCOM link was lost for the first time (sometime between 1707:48 and 1803:41 - page 54, although it seems not unreasonable to assume that it was lost at 1737 when the next ACARS report was due - page 50) - at each subsequent Log-on (1825:34 and 0019:37 the next day), no Flight ID was provided (page 53), and no further ACARS reports were transmitted (page 50). Those Log-on were both Class 3, not Class 1 - see Class 1 Log-on at 1250.19 that did not provide a Flight ID either (page 54).
The report indicates that the SATCOM unit was not manually logged off from within the cockpit (page 54).
Is anyone able to provide their thoughts as to why Flight ID and ACARS data was not provided at and subsequent to that Log-On? Would it have been possible for someone within the plane to prevent the Flight ID and ACARS reports from being provided? If so, what purpose could someone have thought that might serve? Could they have thought they were disabling the entire SATCOM unit in a fashion that did not evidence a manual log-off from the cockpit? Could this have occurred as a result of someone pulling a circuit breaker to the SATCOM?
What would make the SATCOM unit try to reconnect if it had simply lost the satellite link - would it automatically try again after a preset period?
It seems oddly coincidental that SATCOM would reconnect at 1825:25, shortly after disappearing from radar contact and prior to turning South (ATSB 8 October refinement report at page 8) or, possibly as the aircraft began to turn South.
Is there any reason someone flying the plane would have need of any particular aircraft subsystem (say to set the auto-pilot) that might have lead to the SATCOM being inadvertently reconnected?
Apologies for any questions that have been done to death on here already.
'Abrupt' disappearance
At page 3 the report states:
"The tracking by the Military continued as the radar return was observed to be heading towards waypoint MEKAR, a waypoint on Airways N571 when it disappeared abruptly at 1822:12 UTC [0222:12 MYT],10 nautical miles (Nm) after waypoint MEKAR."
Bolding is mine - while this is almost certainly meaningless, this seems an emotive choice of words, perhaps? Is it usual for primary returns to disappear 'abruptly' if an aircraft is proceeding out of radar coverage in straight and level flight? If not, aside from an event which disintegrated the airframe, is there any course of action that is likely to result in such an 'abrupt' disappearance? I am assuming that radar coverage is poor at distance and closer to the land or sea (hence the military practice of 'terrain masking') - would a widebody rapidly descending towards the outer limits of radar coverage be more likely to deliver such an 'abrupt' disappearance, and would it be apparent that such a manoeuver was being carried out prior to that point?
SATCOM link lost, lack of Flight ID and no further ACARS on subsequent Log-on
As I understand it, Flight ID for GES logon is provided by the aircraft's AIMS units (of which there are two - page 49). These also provide ACARS reporting.
After the SATCOM link was lost for the first time (sometime between 1707:48 and 1803:41 - page 54, although it seems not unreasonable to assume that it was lost at 1737 when the next ACARS report was due - page 50) - at each subsequent Log-on (1825:34 and 0019:37 the next day), no Flight ID was provided (page 53), and no further ACARS reports were transmitted (page 50). Those Log-on were both Class 3, not Class 1 - see Class 1 Log-on at 1250.19 that did not provide a Flight ID either (page 54).
The report indicates that the SATCOM unit was not manually logged off from within the cockpit (page 54).
Is anyone able to provide their thoughts as to why Flight ID and ACARS data was not provided at and subsequent to that Log-On? Would it have been possible for someone within the plane to prevent the Flight ID and ACARS reports from being provided? If so, what purpose could someone have thought that might serve? Could they have thought they were disabling the entire SATCOM unit in a fashion that did not evidence a manual log-off from the cockpit? Could this have occurred as a result of someone pulling a circuit breaker to the SATCOM?
What would make the SATCOM unit try to reconnect if it had simply lost the satellite link - would it automatically try again after a preset period?
It seems oddly coincidental that SATCOM would reconnect at 1825:25, shortly after disappearing from radar contact and prior to turning South (ATSB 8 October refinement report at page 8) or, possibly as the aircraft began to turn South.
Is there any reason someone flying the plane would have need of any particular aircraft subsystem (say to set the auto-pilot) that might have lead to the SATCOM being inadvertently reconnected?