A second flight tracker has put a number on the disruption. Flightradar24 said more than 1,000 flights had been cancelled across the US because of the ground halt, according to the Globe and Mail, which gives the figure as of just before 6pm ET on Friday 13 November.
That is lower than the 1,913 cancellations ABC7 San Francisco reported from FlightAware at 6.04pm ET. The two counts come from different trackers and may not be comparable.
Flightradar24's figure is described as cancellations caused by the ground halt. ABC7 did not say whether the FlightAware count covers the whole of Friday or only flights affected by the FAA's order, and earlier FlightAware figures were whole-day totals.
Neither count has been independently checked.
The Globe and Mail also reports that Canadian airports say outbound flights to the US are delayed by the grounding, as are international flights that would normally cross US airspace.