US airspace reopened at 8.15pm Eastern time on Friday, Duffy told a Friday night news briefing, CBS News reports. Flightradar24 gives the lift time as 01.15 UTC on 14 November.
The FAA says it "thoroughly tested" its systems before lifting the ground stop, to confirm they were stable and reliable before clearing flights to resume, according to AP via KSTP. Earlier reports said the stop was over but gave no exact time and no word on safety checks.
Flightradar24 says the stop was issued at 20.54 UTC on 13 November. That means it lasted about four hours and 20 minutes, which is consistent with earlier reports that it ran for more than four hours.
Some departures are resuming, but the FAA has warned that recovery will take time. CNBC reports that more than 10,000 flights were disrupted and that delays and cancellations are set to stretch into the weekend. It does not say how many were cancelled and how many delayed. CNN reports that JetBlue cancelled its remaining Friday flights and expects disruption to continue into Saturday.