Homeland Security Secretary Markwayne Mullin says two areas of the US are not currently affected by the communications outage behind the nationwide ground stop, CBS Chicago reports. He would not say which.
Mullin, speaking to reporters on Friday evening, described the problem as a telecommunications outage affecting the ability of air traffic control and planes to communicate, according to CBS Chicago.
His account sits closer to the FAA's wording than to that of Transportation Secretary Sean Duffy. Duffy said the issue was affecting "all" Air Route Traffic Control Centers, while the FAA referred to "multiple" centres.
Mullin's claim has not been independently checked. The FAA has not said which parts of the country are affected.
CBS Chicago also reports Duffy as saying the ground stop was issued "out of an abundance of caution".
No cause has been given. Aviation Hub reports that Mullin is refusing to rule out any cause.