Even if the federal government reopens on Wednesday when the House returns to vote on a funding deal already approved by the Senate, travel experts warned Thanksgiving could be a headache at airports.

On Tuesday, the shutdown isn't ended.

Approximately 130 flights were cancelled at O'Hare on Tuesday, the second most in the U.S. behind LaGuardia Airport in New York.

Duffy warned, if the government does not reopen soon, airlines will have to start grounding flights and not fly.

While there were no crowds and no backups at TSA security checkpoints at O'Hare on Tuesday, travelers Nishanth Bhaskara and Aimen Churram said looks are deceiving.

"I think a lot of flights have been canceled. I think that people are not here because they all went home," Bhaskara said.

Monday night, Bhaskara and Churram were supposed to fly to New York, but their flight was cancelled. They were back at O'Hare on Tuesday, and once again waiting.

"Finally got the last flight out today, and here we are, that's delayed as well," he said.

During his visit to O'Hare, Duffy sent a stern message that future travel depends on air traffic controllers coming back to work.

"I encourage all of them to come to work, to be patriots, and to help navigate the airspace effectively for the American people," he said.

With the government shut down, air traffic controllers haven't been paid in weeks, so some are not showing up.

If the House of Representatives does not vote on a resolution to reopen the government on Wednesday, Duffy said this weekend will be a taste of what Thanksgiving air travel will look like.

"I'm going to tell you, we are not going to get to Thanksgiving. You are going to see this Friday, Saturday and Sunday; big disruption thus far. Massively more disruption as we come into the weekend if the government doesn't open," he said.

Suzanne Morrow, CEO of InsureMyTrip travel insurance, said people should anticipate lengthy delays at the airports.

"And I don't just mean 'your flight is delayed.' I mean long TSA lines, long check-in lines," she said.

Morrow recommended people purchase travel insurance through a retailer, not through an airline this holiday season, in case problems arise.

"You can get better coverage probably for less money, and then you can get the coverage that matters to you," she said.

Others said don't fly in general.

"I don't think it's a good time to travel at all. So if you have to be at work or school the next day, then I would advise against it," Aimen said.

Meantime, Duffy said he supports bonuses for air traffic controllers who have reported to work each day of the shutdown, but was less firm on the president's threat to penalize controllers who called in sick.

He also said paychecks would resume for controllers within 48 days of the shutdown ending, although he couldn't commit to how they'll roll back the recent flight reductions.