Airspace: Its Different In The Dark

Airspace regulations and boundaries are hard enough to get straight under normal conditions — but when the sun goes down everything changes.

The whole idea of regulating airspace is to provide pilots with the best chance to see other aircraft and avoid collisions. Being able to see other aircraft depends on the ability to see. The ability to see depends on whether or not visibility is restricted by either meteorlogical conditions… or lack of light. When it gets dark it is harder to see and therefore some of the airspace rules change.


  • In the daytime pilots flying in Class G airspace can legally get by with 1 mile visibility — but in darkness, that requirement increases to 3 miles.Exception: Part 91.155 says: “When the visibility is less than 3 statute miles but not less than 1 statute mile during night hours, an airplane may be operated clear of clouds if operated in an airport traffic pattern within one-half mile of the runway.”

    Translation: You and I could go out and practice our takeoffs and landings (full stop for night currency) in one mile visibility at night — as long as we stayed one-half mile from the runway while flying the pattern.

  • Also, the ability to ask for and receive a Special VFR changes. To get a Special VFR at night you must be instrument rated and flying an instrument equipped aircraft. This always seemed a bit absurd — If you were IFR rated, why not just get an IFR clearance and eliminate the need for a Special VFR altogether?

The other problem with airspace at night is that it often changes as airport services change. We know that Class D airports have an operating control tower — but what happens when the tower closes for the night? We know that Class E can only touch the surface when a weather observer is present — but what happens when the weather observer goes home for the night? The airspace changes.

A magenta dashed ring around an airport is indicative of Class E airspace that comes down to the ground inside the ring. Look at Figure 1a of the Northwest Alabama Regional airport. But the chart has a note (printed northeast of the airport symbol) that says “see NOTAMs Directory for class E (sfc) eff hrs.”

Translation: The weather observer will not be at this airport 24 hours a day and pilots are directed to check NOTAMs or look up the “class E to the surface effective hours” in the Airport Facilities Directory. I looked up this airport in the directory and this is what it says: “Airspace: Class E service effective 1200-0400Z, other times Class G.

What It Means To You: A.M. Between 6:00 a.m. and 10 p.m. CST, the airspace is Class E, and therefore VFR flight into the airport with less than 3 miles is not allowed. (See below.)


CLASS D IN THE DARK*P.M. But after 10 o’clock at night and before 6 o’clock in the morning the airspace changes to Class G. A VFR pilot could fly to the Northwest Alabama Regional airport at 5:30 am (after sunrise) with only 1 mile visibility as long as they stayed low in Class G airspace. (See below.)

A blue dashed ring signifies a Class D airport. But if the airport also has a note about airspace printed on the chart (southeast of the airport symbol), special rules apply. Look at Figure 2a of Athens/Epps airport, below. There is a notation that says, “see NOTAMs/Directory for Class D eff hrs.” When I checked the directory for this airport the airspace section read: “Class D service effective 1330-0330Z, other times Class E.”

What that means to you:
A.M. At 8:30 a.m. EST the Control Tower opens and the airspace becomes Class D. (See below.)


AN EYE ON CHANGING SKIESP.M. But at 10:30 p.m. the Tower closes and Class D airspace disappears, leaving Class E in its place until the next morning when the tower opens again. (See below.)

Pilots must be careful about airspace changes that take place at different times during the day. At 8:00 am the Athens airport is an uncontrolled airport. Approaching pilots should use the Common Traffic Advisory Frequency of 126.3 (noted by the letter C in the blue ball beside the control tower frequency) and call for ‘Athens Traffic.’ But at 8:30 am Athens is a controlled airport and arriving pilots would call ‘Athens Tower.’

BOTTOM LINE: It pays to be able to read airspace. Practice your GMT conversions, consult the Airport Facilities Directory … and take a watch that keeps good time. Sometimes, where you are depends on the time of the day.