Malaysia Airlines Flight 370 Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! ==== Analysis ==== [[File:MH370 location probability heat map per DST Group analysis.jpg|thumb|A [[heat map]] indicating the probable location of missing Flight 370 based on a [[Bayesian search theory|Bayesian analysis]] of possible flight paths by Australia's [[Defence Science and Technology Group]]<!-- Note: Original file name included "HeatMap", which is why it's being added here. Original file URL: http://jacc.gov.au/media/maps/files/20151201_IndicativeArea_Bathy_DSTO_HeatMap_A4.jpg --><ref>{{Cite report |date=3 December 2015 |title=MH370 β Definition of Underwater Search Areas |url=http://www.atsb.gov.au/media/5733650/AE-2014-054_MH370-Definition%20of%20Underwater%20Search%20Areas_3Dec2015.pdf |publisher=[[Australian Transport Safety Bureau]] |access-date=3 December 2015 |archive-date=12 April 2021 |archive-url=https://web.archive.org/web/20210412232900/http://www.atsb.gov.au/media/5733650/AE-2014-054_MH370-Definition%20of%20Underwater%20Search%20Areas_3Dec2015.pdf |url-status=live }}</ref>]] Two parameters associated with these transmissions that were recorded in a log at the ground station were key to the investigation: * Burst time offset (BTO) β the time difference between when a signal is sent from the ground station and when the response is received. This measure is proportional to twice the distance from the ground station via the satellite to the aircraft and includes the time that the SDU takes between receiving and responding to the message and time between reception and processing at the ground station. This measure was analysed to determine the distance between the satellite and the aircraft at the time each of the seven handshakes occurred, and thereby defining seven circles on the Earth's surface<!---(conceptually it should be up in the air at flight level)--> the points on whose circumference are equidistant from the satellite at the calculated distance. Those circles were then reduced to arcs by eliminating those parts of each circle that lay outside the aircraft's range.<ref name=ATSB />{{Rp|18}}<ref name=JN-Inmarsat />{{rp|4β6}} * Burst frequency offset (BFO) β the difference between the expected and received frequency of transmissions. The difference is caused by [[Doppler effect|Doppler shifts]] as the signals travelled from the aircraft to the satellite to the ground station; the frequency translations made in the satellite and at the ground station; a small, constant error (bias) in the SDU that results from drift and ageing; and compensation applied by the SDU to counter the Doppler shift on the uplink. This measure was analysed to determine the aircraft's speed and heading, but multiple combinations of speed and heading can be valid solutions.<ref name=ATSB />{{Rp|18}}<ref name=JN-Inmarsat />{{rp|9β11}} By combining the distance between the aircraft and satellite, speed, and heading with aircraft performance constraints (e.g. fuel consumption, possible speeds and altitudes), investigators generated candidate paths that were analysed separately by two methods. The first assumed the aircraft was flying on one of the three [[autopilot]] modes (two are further affected by whether the navigation system used magnetic north or true north as a reference), calculated the BTO and BFO values along these routes, and compared them with the values recorded from Flight 370. The second method generated paths which had the aircraft's speed and heading adjusted at the time of each handshake to minimise the difference between the calculated BFO of the path and the values recorded from Flight 370.<ref name=ATSB />{{Rp|18, 25β28}}<ref name="ATSB Flight path update"/>{{Rp|10β11}} A [[probability distribution]] for each method at the BTO arc of the sixth handshake of the two methods was created and then compared; 80% of the highest probability paths for both analyses combined intersect the BTO arc of the sixth handshake between 32.5Β°S and 38.1Β°S, which can be extrapolated to 33.5Β°S and 38.3Β°S along the BTO arc of the seventh handshake.<ref name="ATSB Flight path update" />{{Rp|12}} Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. You are also promising us that you wrote this yourself, or copied it from a public domain or similar free resource (see Christianpedia:Copyrights for details). Do not submit copyrighted work without permission! Cancel Editing help (opens in new window) Discuss this page