A total of 32,578 flights were delayed within, into or out of the United States as of 8:07 a.m. ET (1255 GMT), flight tracking website FlightAware showed, without citing reasons. Another 409 within, into or out of the country were also cancelled.
US flights grounded: The FAA said it was working towards restoring its Notice to Air Missions System (NOTAM).
It was the second straight day of major disruptions and the worst day for cancellations since mid-June.
Flight update: Evacuation flights and air bubble flights to and from Indian cities.