The acting head of the U.S. Federal Aviation Administration (FAA) announced he will resign from the agency this summer. 

Acting administrator Billy Nolen made the announcement on Friday after a year of service in his current position. He previously worked for the FAA as an associate administrator in January 2022.

Nolen's farewell letter is a blow to the FAA, which has not had a Senate-appointed administrator since April 2022.

In March, President Biden's hopeful FAA administrator pick Phillip Washington withdrew himself from consideration after it was reported that Arizona Sen. Kyrsten Sinema hesitated to support him amid Republican criticism.

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The announcement comes as air travelers brace for significant delays this summer, as travel levels are expected to return to pre-pandemic levels. 

Despite the uncertainty of the future, Nolen said in a farewell letter that he is "immensely proud" of his accomplishments at the FAA.

"The majority of certification reform is done," the letter reads. "Rules that languished for years, like more robust flight attendant rest rules and SMS for airports, are final."

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"We have not been afraid to act to preserve the safest era in aviation history but to also say that our current record is not good enough," Nolen added. "We should build a system so safe it doesn’t require heroic intervention."

Transportation Secretary Pete Buttigieg called Nolen a "dedicated public servant" in a press release.

"I can speak for everyone at DOT in saying that his skill and expertise are a great asset to this department, and will continue to be as FAA prepares for its upcoming leadership transition," the statement read.

Reuters contributed to this report.