The logged transmission round trip GroundStation -> Sat -> Aircraft -> Sat -> GroundStation provided an non unique "arc of travel" across the globe that was used by Australia to narrow the search area to a truckload of ocean floor that was substantially smaller than the entire planet.
The archived versions of the logs saved by the Malaysian gov are:
https://web.archive.org/web/20160304040818/http://www.dca.go...
Alternating sat routing would have given a more definitive fix and removed the ambiguity.
Your source conveniently omits weird data in the logs that start at 18:39:55UTC (a bunch of zeros, like something errored out).
Satellite pings switch to IOR at 15:59UTC and never change back to POR despite the plane flying east towards it. Going east until 17:21 UTC the plane should have pinged POR but doesn't
The specific issue I have with hyper focused attention on these specific logs and hoorah about "weird data" is that I haven't seen much in the way of properly comparative analysis of a super set of broad fleet Inmarsat logs ... these in general are the trailing edge of quality data, riddled with nuls, semi handshakes, line noise, etc.
Transponders are for positioning, black boxes for logging important flight data, diagnostic interfaces for mechanics in hangers ... and component level Inmarsat .. pretty much not more than a curiousity of "because we can" that's occasionally useful when a properly formed messages truly indicates an inflight issue.
Ping routing and ping times were never meant to be consistent nor used for gross "half-LORAN" positioning .. this is all happenstance after event signal engineering hack work.
Any serious military is tracking all known imaging/SAR satellites and uses their fly-by times (which are entirely predictable), and uses this information for moving stuff covertly. I.e. you want to be out in the open in Area 51 testing a new RQ-180 derivative only when no one can be looking at you right now.
Also, there are global ADS-B satellite relays, and frankly I don't know why this data wasn't logged - it must be explained somewhere. There's a guy on Twitter who captures those on a custom antenna + BladeRF setups (this data is plugged into adsbexchange for oceanic routes coverage). AIS relies even more on satellite relays, as the curvature of the planet limits signal propagation much more than for airplanes. What you see on any AIS website is mostly from a satellite.