Transportation Secretary Sean Duffy and Homeland Security Secretary Markwayne Mullin have put a time on the router fault behind the nationwide US ground stop. They dated the start of the routers' instability to 3.36pm ET on Friday, when more than 3,500 flights were airborne over the US, The Air Current reports.
The timing comes from Friday evening's White House briefing, where Duffy blamed overloaded, ageing routers. CBC also reports Duffy giving 3.36pm ET as the time the FAA experienced telecoms problems.
The 3,500 figure is the first official count of flights in the air. Earlier unofficial counts of 3,100 and 4,042 measured slightly different moments, so the numbers are not directly comparable.
According to CBC, Duffy said the specific issue was instability in communications with planes and radar data at the FAA's 22 regional air traffic control centres. He said: "It's an old system that went down and went down everywhere. It got overloaded."
Duffy said ARTCC and TRACON facilities were operational again, The Air Current reports. He expected recovery to stretch into the weekend, depending on whether crews, pilots and flight attendants are available.
The Air Current gives 3.44pm ET as the time the ground stop was issued. The FAA advisory and other outlets give 3.54pm ET, and the two times have not been reconciled.