Flights are slowly returning to normal in the US, although airlines are warning of the possibility of further delays. This comes after the US Federal Aviation Administration systemfailed yesterday (January 11), grounding all US flights.

The disruption was due to a damaged database file, according to the FAA, who have addedthat at this time, there is no evidence of a cyber-attack. President Joe Biden has now called for a full investigation into the cause of the lengthy disruption.

By last night, almost 10 000 inbound and outbound flights had been delayed and more than 1 300 cancelled.

Even with the system returning to full operation, Captain Chris Torres, VP of the Allied Pilots Association, tells Reuters that delays could last until the weekend due to crowded gates. "This thing was lifted at 09h00 Eastern. That doesn't mean the problem stops at 9am.This is going to cause ripple effects."

United Airlines will waive change fees and any difference in fare for customers rescheduling flights departing on or before January 16, the BBC reports.

Delta has also issued a waiver for customers affected by the FAA ground stop to rebook travel. The fare difference waiver for flights gives flexibility to change flights, even if they are not delayed or cancelled.

Delta teams are working to contain the impact. Approximately 150 Delta and Delta Connection flight cancellations became necessary yesterday out of 4 301 scheduled departures. While potential for additional delays and cancellations continue, Delta expects minimal residual impact, if any, today (January 12).