Still on the way but very odd, wildly zig-zagged. Tracking problem perhaps?
flightaware.com/live/flight/ANA1 … /KSEA/RJAA
or perhaps caused by weather diversion?
Ratty data
Read all of the stuff right below the map. You’ll see “At least part of this flight occurs outside of FlightAware’s primary service area” and right next to it will be a link. Click on this link to read more information about the primary service area.
The zig-zag in question appears within FlightAware’s service area.
When this sort of zig-zag pattern has appeared in the past, the explanation has been that the aircraft entered a zone that was being tracked by two different centers - and both centers are feeding data to FlightAware in an alternating fashion.