The staffing problems were at air traffic centers in Jacksonville, Florida and a Washington D.C. center that controls high-altitude air traffic over seven states. He said safety is being maintained during a period of "minimal impacts" on travel.
President Donald Trump has been briefed on the situation, a spokeswoman said.
"We are in regular contact with officials at the Department of Transportation and the FAA", Sanders said in a statement.
Find more information on incoming and outgoing flights from Cleveland here.
"No one can predict what impact it will have as it continues", Southwest chief executive Gary Kelly said of the shutdown on Thursday. "I travel every week, and nothing surprises me".
Trump says he would accept a deal to at least temporarily re-open the federal government if it contained a "pro-rated down payment" on the U.S. -Mexico border wall he has sought for two years.
The stark portrayal presented to the White House of a prolonged shutdown coupled with a shortage of Transportation Safety Administration officers and Friday's massive delays were a "contributing catalyst" for the agreement ending the shutdown, the source said.
"This is exactly what AFA and other aviation unions have been warning would happen", the Association of Flight Attendants-CWA said in a statement released Friday, before Trump announced he would sign a bill to re-open the government through February 15.
Giuliani walks back statements of Trump's involvement in Moscow project
Cohen, unlike in the Southern of District of NY case against him, did not say that Trump "directed" him to commit a crime. Smith said BuzzFeed is "eager" to understand which parts of the report Mueller's office is challenging as inaccurate.
Union President Paul Rinaldi said Friday that the union does not condone a coordinated action that would reduce the capacity of the nation's airspace. The reason is described as a shortage of flight traffic controllers at the airport.
Earlier Thursday the Senate failed to end the shutdown - the longest in US history - voting down two competing proposals that would have ended the impasse over funding for the wall. House Speaker Nancy Pelosi said on Friday that the shutdown was "pushing our airspace to the breaking point". Each passing hour makes the situation worse, he said.
Six out of 13 controllers scheduled to work in the DC area center called out today, aviation officials told ABC News.
Just days after a federal judge denied a union bid to end the government shutdown, some of the nation's busiest airports ground to a halt due to "staffing" issues.
Philadelphia International Airport had reported departure delays of 1 hour and 14 minutes, but those have dropped back to normal operations by 11 a.m. LaGuardia delays were averaging 1 hour 26 minutes.
Baltimore/Washington International Thurgood Marshall Airport had the second-longest wait time, of 19 minutes.
Devine said the people he represents work in a job where "they have to be right 100 per cent of the time" or tragedy could strike, but that the shutdown has made that more hard. "We're trying to get everyone involved to work something out".
Air traffic controller staffing nationwide also already had been a key FAA consideration. Controllers prioritize safety, they said, and can only handle so much traffic at one time.