TO LIGHT OR NOT TO LIGHT

The question frequently arises as to when it is required to operate the various lights on the airplane.

There are two kinds of lights generally involved in this question:

Position lights, also called navigation lights. These are the red, green, and white lights that allow the orientation of the airplane to be determined by observing the spatial pattern of the colored lights.
Anticollision lights. These include rotating lights or flashing lights, such as the tail beacon and strobes.

First let’s examine what lights are required to be on the airplane.

Day VFR:

91.205(b)(11) For small civil airplanes certificated after March 11, 1996, in accordance with part 23 of this chapter, an approved aviation red or aviation white anticollision light system. In the event of failure of any light of the anticollision light system, operation of the aircraft may continue to a location where repairs or replacement can be made.

Night VFR:

FAR 91.205(c)

(1) Instruments and equipment specified in paragraph (b) of this section.

(2) Approved position lights.

(3) An approved aviation red or aviation white anticollision light system on all U.S.-registered civil aircraft. Anticollision light systems initially installed after August 11, 1971, on aircraft for which a type certificate was issued or applied for before August 11, 1971, must at least meet the anticollision light standards of part 23, 25, 27, or 29 of this chapter, as applicable, that were in effect on August 10, 1971, except that the color may be either aviation red or aviation white. In the event of failure of any light of the anticollision light system, operations with the aircraft may be continued to a stop where repairs or replacement can be made.

(4) If the aircraft is operated for hire, one electric landing light.

No additional lighting is required for IFR.

Certification requirements for position lights are in FAR 23.1385-1397, and there are no surprises. It is worth noting that there is no requirement that the position lights be steady-burning rather than flashing, and indeed some airplanes do have flashing position lights.

FAR 23.1401 covers anticollision lights. There is no requirement for the number or location of these lights, only that they must be visible from seventy-five degrees below to seventy-five degrees above the horizontal plane of the airplane, with not more than a total of 0.5 steradian of solid angle obstructed. They may be either red or white.

Note that there is no mention of a tail beacon, rotating or flashing. Even in 1965 there was no requirement for a tail beacon, it seems to just be a common design feature. A tail beacon, rotating or flashing, would be considered part of the anticollision light system.

Now we return to the question of when the above lighting systems must be in use.

§91.209 Aircraft lights.

No person may:

(a) During the period from sunset to sunrise (or, in Alaska, during the period a prominent unlighted object cannot be seen from a distance of 3 statute miles or the sun is more than 6 degrees below the horizon) --

(1) Operate an aircraft unless it has lighted position lights;

(2) Park or move an aircraft in, or in dangerous proximity to, a night flight operations area of an airport unless the aircraft --

(i) Is clearly illuminated;

(ii) Has lighted position lights; or

(iii) is in an area that is marked by obstruction lights;

(3) Anchor an aircraft unless the aircraft --

(i) Has lighted anchor lights; or

(ii) Is in an area where anchor lights are not required on vessels; or

(b) Operate an aircraft that is equipped with an anticollision light system, unless it has lighted anticollision lights. However, the anticollision lights need not be lighted when the pilot-in-command determines that, because of operating conditions, it would be in the interest of safety to turn the lights off.

So position lights (nav lights) must be on from sunset to sunrise (not just during official FAA night). Anticollision lights must be on during the day if the aircraft is equipped with them, as most airplanes are required to be (maybe some real old ones excepted), when the airplane is being operated. For night flight, all U.S. certified planes are required to have anticollision lights, and they must be on when the airplane is being operated.

What does “operated” mean? It is undefined. One could say that operation begins once the engine is started, for powered airplanes. Or one could say that operation of a powered airplane begins once it begins moving under its own power. The more conservative approach is the engine started definition.

For airplanes with separate controls for the tail beacon and the remaining anticollision lights, it is common practice to turn on the tail beacon before engine start. However, that does not meet the requirement for having the anticollision lights lighted once operation begins. Once operation begins, all the anticollision lights must be lighted.

There is a provision for the PIC to determine whether operation of the anticollision lights will not be in the interest of safety. Examples of this would be when the airplane is being operated in fog or clouds where the flashing lights can cause disorientation of the pilot, or when the flashing lights will interfere with the vision of the pilot in another airplane parked close by or passing close by. It is a courtesy to turn off strobes when operating close to another operating aircraft, but there is no reason to turn off the tail beacon unless it is also very bright. Usually the wingtip strobes are the main problem.