Commercial Pilot License (CPL) Practice Exam

The correct answer indicates that when a control tower in Class D airspace closes, the lower limit of controlled airspace transitions to Class E airspace starting at 700 feet above ground level. This is based on the regulations governing airspace classification in the United States.

In areas where Class D airspace exists, the airspace is controlled primarily to manage traffic around airports with operating control towers. When the control tower closes, the airspace no longer has the same level of air traffic control oversight. However, it doesn’t simply revert to uncontrolled status at all altitudes. Instead, the airspace generally retains a degree of control above a certain altitude, which leads to the establishment of Class E airspace, typically beginning at 700 feet AGL.

When we consider the options that suggest the airspace transitions to Class G or remains Class D at all altitudes, they do not accurately reflect how airspace classifications are structured after tower closure. Class G airspace denotes uncontrolled airspace, which would only apply at lower altitudes unless specifically designated otherwise. Thus, Class E airspace becoming the controlling class above 700 feet AGL accurately reflects the operational transition that occurs following a control tower's closure in Class D airspace.