The potential delay comes just two days after Houston’s William P. Hobby Airport issued a ground stop Tuesday afternoon for the same reason. That ground stop lasted until 6 p.m., while a ground delay continued until 9 p.m., according to Houston Airports.

The first thing to note is that things can change fast. But as of this morning, 4% of flights are being canceled across 40 “high-volume” airports. The list is publicly available, but it includes most of the big hubs across the United States, such as Atlanta, New York’s airports, Chicago O'Hare, Los Angeles International and Dallas/Fort Worth.

Flights were delayed at Phoenix Sky Harbor Airport on Tuesday, Nov. 4 and again on Wednesday. What travelers should know about the ground delay.

Federal investigators to examine the deadly UPS cargo plane crash in Louisville as the death toll climbs to at least 13 people.