On September 14, 2001, “Effective at 12:15 p.m., FAA [Federal Aviation Administration] reauthorized agricultural flight operations (crop dusting) under Part 137. Effective at 4:00 p.m., DOT [Department of Transportation] approved reopening of the airspace to certain general aviation flights. Instrument Flight Rules (IFR) operations were permitted, except within two areas under Temporary Flight Restrictions that extended 25 nautical miles from New York Kennedy and Washington Reagan National airports.”
– FAA, “Chronology of the September 11 Attacks and Subsequent Events Through October 24, 2001,” FAA Believed Second 9/11 Plane Heading Towards NY for Emergency Landing, The National Security Archive, Sep. 9, 2005