Today's BA219 from LHR to DEN (2018-03-20) appeared to fly 5 zigzags just before and over the Hudson Bay in Canada at around 18:15z. Prior to that, its flight path matched its planned route very closely.

I know that congestion avoidance can sometimes lead to flights being asked to fly doglegs (as in Why did this plane fly in a zigzag pattern?), but this flight was still 3 hours from its destination and still exceeding planned speed when it appeared to fly zigzags. I don't see any weather issues on radar at the time.

After the zigzags seen in the FlightAware capture, the flight track straightened up and flew parallel to its planned route. This appears to be a track data problem, not the actual plane's path.

BA219 flight path over Hudson Bay

But on FR24 that path is not there:

enter image description here

I've seen 'Why do aircraft on Flight Radar 24 jump around randomly sometimes?', since they are different services, what could be the reasons for FlightAware to behave like this? Also note the linked FR24 post is a different more jagged path than the one here.

FlightAware tracks from other flights show similar zigzags in the Hudson Bay area. Presumably this is just noisy tracking data. Any idea why that happens in this particular location?