FAA-H-8083-25C, ch. 14, and AIM 4-3-6

Reading runway numbers and markings

Runway numbers are a compass heading in disguise. Knowing how they are formed, and what the other painted markings say, is a short and reliable exam topic.

Part 107, explained › Operations · Last reviewed October 25, 2026 against the eCFR and faa.gov. UAV Campus is not affiliated with the FAA.

What do runway numbers and markings mean?

A runway number is the whole number nearest one-tenth of the runway centerline's magnetic azimuth, so 183 degrees becomes runway 18. Parallel runways add L, C or R. A basic VFR runway may have only a centerline and numbers, and yellow Xs at the ends mark a closed runway.

Runway numbers and letters are determined from the approach direction and are measured clockwise from magnetic north, not true north. The AIM gives two examples: a magnetic azimuth of 183 degrees is runway 18, and 87 degrees is runway 9. For an azimuth ending in 5, such as 185, the designation could be either 18 or 19. When parallel runways share the same azimuth, a letter (L, C or R) is added, shown from left to right as seen from the direction of approach.

Closed runways: for a permanently closed runway the threshold, designation and touchdown markings are obliterated and yellow Xs are placed at each end and at 1,000-foot intervals. For a temporarily closed runway, yellow Xs or raised lighted yellow Xs are often placed at each end, but a visual indication may not be present, so the PHAK says to always check NOTAMs and ATIS for closure information.

For a remote pilot, AC 107-2A says to avoid operating in any area where the drone may interfere with airport operations, such as approach corridors, taxiways, runways or helipads (14 CFR 107.43). That rule is explained on our 14 CFR 107.41 to 107.43 page.

Sources: FAA-H-8083-25C, ch. 14, Runway Markings and Signs · FAA-H-8083-25C, ch. 14, Runway Designation Marking · FAA-H-8083-25C, ch. 14, Closed Runways · FAA-H-8083-25C, ch. 14, Permanently Closed Runways · AIM 4-3-6, Use of Runways/Declared Distances · AC 107-2A, 5.10.1

What the FAA says

FAA-H-8083-25C, ch. 14, Runway Designation Marking

Runway numbers and letters are determined from the approach direction. The runway number is the whole number nearest one-tenth the magnetic azimuth of the centerline of the runway, measured clockwise from the magnetic north.

AIM 4-3-6, Use of Runways/Declared Distances

For example, where the magnetic azimuth is 183 degrees, the runway designation would be 18; for a magnetic azimuth of 87 degrees, the runway designation would be 9.

FAA-H-8083-25C, ch. 14, Runway Markings and Signs

A basic VFR runway may only have centerline markings and runway numbers.

FAA-H-8083-25C, ch. 14, Temporarily Closed Runways and Taxiways

As discussed previously in the chapter, you must always check NOTAMs and ATIS for runway and taxiway closure information.

Sources: FAA-H-8083-25C, ch. 14, Runway Designation Marking · AIM 4-3-6, Use of Runways/Declared Distances · FAA-H-8083-25C, ch. 14, Runway Markings and Signs · FAA-H-8083-25C, ch. 14, Temporarily Closed Runways and Taxiways

Exam traps

  • Runway numbers are in reference to magnetic north, not true north.
  • The number is the whole number nearest one-tenth of the magnetic azimuth, so 183 degrees is runway 18 and 87 degrees is runway 9.
  • Parallel runways are told apart by a letter added to the number: L, C or R.
  • Yellow Xs at the ends of a runway mark it as closed, but for a temporary closure a visual indication may not be present, so check NOTAMs and ATIS.

Quick quiz: 3 questions

Similar to the FAA test, not the actual test questions. Each answer shows its FAA source.

Question 2 of 3

Area C on the airport depicted is classified as a

FAA testing supplement figure for quiz question 2
Tap the figure to open it full size.
  1. A closed runway.
  2. B multiple heliport.
  3. C stabilized area.
Show the answer
Answer: A. closed runway.

(X symbols on the runway surface indicate that the runway is closed.)

FAA source: FAA-H-8083-25C ch. 14, Temporarily Closed Runways and Taxiways

Question 3 of 3

This sign confirms your position on (Refer to F)

FAA testing supplement figure for quiz question 3
Tap the figure to open it full size.
  1. A taxiway 22.
  2. B routing to runway 22.
  3. C runway 22.
Show the answer
Answer: C. runway 22.

(Black signs with yellow lettering indicate location information. Runways are always identified with numbers. In this case, it indicates that the aircraft is located on runway 22.)

FAA source: FAA-H-8083-25C ch. 14, Airport Signs

What do the letters L, C and R after a runway number mean?

Where there are parallel runways, the letters tell them apart: left (L), right (R) or center (C). Two parallel runways show L or R beneath the number, and three show L, C or R.

Source: FAA-H-8083-25C, ch. 14

What is a relocated runway threshold?

When part of a runway is closed for construction or maintenance, the threshold is relocated. A common marking is a ten foot wide white bar across the width of the runway.

Source: FAA-H-8083-25C, ch. 14

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More on this topic: Part 107 operations and decision-making.