Staffing reductions stemming from furloughs of air traffic controllers caused more than 1,200 delays on 22 April, says the US Federal Aviation Administration in a statement.
These were in addition to more than 1,400 additional delays that day caused by weather and other reasons.
"Travellers can expect to see a wide range of delays that will change throughout the day depending on staffing and weather-related issues," said the administration in a statement.
The FAA says it is "experiencing staffing challenges" at air traffic control centres in New York and Los Angeles and at the Dallas-Fort Worth and Las Vegas terminal radar approach control facilities (TRACONs).
"Controllers will space planes farther apart so they can manage traffic with current staff, which will lead to delays at airports including DFW, Las Vegas and LAX," said the administration. "The FAA also expects delays at Newark and LaGuardia because of weather and winds."
As of 14:00 EST on 23 April, the FAA's website showed Los Angeles International airport and Dallas-Fort Worth airport experiencing delays of 31-45 minutes. Washington National and Washington Dulles International also showed delays attributed to staffing issues. Newark Liberty International airport, LaGuardia Airport and John F. Kennedy International airport were also experiencing delays due to weather and other issues.
FAA administrator Michael Huerta said during a Senate committee hearing on 16 April that the furloughs could cause delays of up to 90 minutes at larger airports. Flightglobal reported on 22 April that there were reports of flight delays at several airports on the east coast, however it was unclear to what extent the furloughs were prompting them.
One of those airports with delays was Charlotte, which the FAA's website had said was undergoing delays due to staffing. US Airways told Flightglobal that the furloughs were causing delays at its hub there, as well as delays of 60 to 90 minutes on shuttle flights from Washington National airport to New York LaGuardia.
The FAA must trim its budget by $637 million due to across-the-board federal budget cuts. It informed airlines last week that it would implement the furloughs, which went into effect on 21 April and will last through September.
Huerta told the US Senate that the furloughs would represent about 10% of "available controller hours" at large airports, totalling 11 furlough days for each of the administration's 47,000 employees.
On 19 April, A4A filed an emergency stay in federal court requesting the court block the FAA's planned furloughs. The group also filed a petition asking the court to review the FAA's decision to furlough air traffic controllers.
The court denied the emergency stay, but has not ruled on the review. A4A said the court challenge is ongoing.
John Hemmerdinger and Edward Russell contributed to this report.