Source: Global Travel Industry News

Low visibility may be the reason hundreds of flights in Chicago were cancelled today. The weather didn't look that bad according to eTN sources, except for thunderstorms earlier in the day. According to ABC News in Chicago, low visibility made it impossible for mostly smaller aircraft to land. Making the situation worse, more storms rolled across the Chicago area Thursday afternoon and evening. Patchy, dense fog also affected parts of Chicago, Waukegan, Gary, and Valparaiso on Thursday morning.

People are in line a quarter of a mile long at the United Airlines ticket counters at Chicago O'Hare airport.

Three out of 4 flights today from Chicago to Winnipeg landed in Winnipeg but did not take off, according to eTN Publisher Juergen T. Steinmetz who is at the airport in Winnipeg. Airport hotels around the country and in Canada are booked, with United Airlines passengers waiting for flights.

In Chicago, upset passengers are getting ready to spend the night at the airport with no information as to why flights have been cancelled. Hotels in Chicago are sold out.

Some cancelled flights show weather as a reason, but most show a technical reason.

ETN reached out to United Airlines media relations. A United Airlines spokesperson confirmed a weather-related issue in Chicago.

Since United Airlines is the largest airline operating in Chicago, it may explain most problems are with United at this time.

Sandy Dhuyvetter, host of Travel Talk Radio and eTN affiliate, is one of the passengers currently stranded in Chicago. She said hundreds of flights are cancelled, and United would not give a reason. She also said that other airlines including US Air, American Airlines, Delta, Air Canada, and Lufthansa flights are operating without major delays.

No long lines of passengers are visibile at airline counters at Chicago O'Hare airport except at the United Airlines terminal.

It appears most of the cancelled flights are shorter flights possibly operated on United Express. A cyber-attack rumor is floating around, but United Airlines has not confirmed that.