Reagan airport was closed after 11 September
The two pilots of Frontier Airlines flight 819 have been suspended after reportedly acknowledging errors that took the plane through the most restricted airspace in the United States.
The plane failed to make a steep turn after take-off and flew almost directly over the White House, where President George W Bush was at the time.
There have always been security precautions for government buildings in Washington, but these were tightened after the 11 September attack on the Pentagon - and fighter jets continue to patrol the skies.
The Frontier Boeing 737 plane took off from Reagan National Airport - just across the Potomac River from the Washington landmarks - at 1815 local time (2345 GMT) heading for Denver, Colorado.
A spokeswoman for the US Federal Aviation Administration said the plane's pilot was contacted by air traffic controllers and acknowledged making an error.
Laura Brown said: "The pilot missed the first turning point.
"He did manage to go through part of the restricted airspace."
She said the plane was monitored by "appropriate security agencies".
Pentagon attacks
A spokeswoman for the Denver-based airline, Tracey Kelly, said the pilots had been grounded by the carrier until federal and company investigations were completed.
"We're working with the FAA and the TSA [Transportation Security Administration] to determine what happened and make sure it does not happen again," Ms Kelly said.
Before the 11 September attacks on the Pentagon and New York, flights departing Reagan National Airport followed the Potomac River, bringing planes close to CIA headquarters, the White House, the Capitol and the Pentagon.
White House security officials were reluctant to reopen the airport after the attacks and allowed flights to resume only gradually.