Handshake 6 — last successful hourly ping

Handshake 6 at 00:10:58 UTC is the last successful hourly keep-alive. BTO from this ping, together with the 00:19 log-on, defines the 7th arc: a locus of points at a common range from the satellite, along which the aircraft is believed to have been at flame-out. Search areas from 2014 through 2026 are all arguments about where on, or how far from, that arc the wreckage lies.