MIAMI (CBS4) – United Airlines grounded 96 Boeing 757 airplanes across the United States late Tuesday to perform maintenance checks.

In South Florida, no delays or cancellations were reported at Miami International Airport or Fort Lauderdale International Airport.

The maintenance checks, which usually took between 60 and 90 minutes, were ordered because the airline found that it had not completed operational checks after updating air data computers following a 2004 federal directive, according to United spokeswoman Megan McCarthy.

By late Wednesday morning, roughly three-quarters of the aircraft had been checked. The company’s “oversight” was found Tuesday during quality assurance checks and the FAA said the move to ground the planes was voluntary.

The federal directive ordered airlines to modify the air data computer system by installing new circuit breakers, relays and related components, along with making wiring changes in and between the flight deck and the main equipment center, according to the Associated Press.