Runway lines and markings help pilots identify the correct runway and how to align their aircraft with that runway during takeoff and landing. Although student pilots learn these markings early in their flight training, even experienced pilots occasionally use the wrong runway. Learning and reviewing these markings could help prevent a runway incursion, or worse, an excursion, a scenario in which the aircraft fails to remain on the runway, potentially leading to an accident.
In October 2019, two pilots holding airline transport pilot certificates landed on the wrong runway during a visual approach in Battle Creek, Michigan (KBTL). According to a NASA Aviation Safety Report (ASRS), Runway 31 was active; however, the pilots requested and were cleared to land on Runway 23R. When the pilot flying began to set up for the final approach to Runway 31, the non-flying pilot corrected the other pilot to fly the base leg for Runway 23. However, from this approach path, the closest runway was actually 23L, which is where the crew landed.
While Runway 23L is parallel to 23R, it is 6,000 feet shorter than the intended runway. Fortunately, the aircraft landed without incident. According to an ASRS narrative, the pilot noted:
“I can only attribute to us both being fatigued a little bit the reason we landed on the wrong runway. We should have gone around when [the] Pilot Flying was confused about the approach to Runway 31. If we had gone around, we would’ve realized the error.”
We are humans and mistakes will happen, which is why we should all do our part to mitigate risks that can cause incidents. Both pilots in the aforementioned incident reported fatigue; however, they also reported that they verified the runway by checking the REILs (runway end identifier lights) against the centerline direction. While both Runways 23L and 23R have REILs at KBTL, the pilots failed to notice several other differences. Runway 23L does not have MALSR (Medium Intensity Approach Lighting System with Runway Alignment Indicator Lights), a stopway, or touchdown zone markings.
Let’s review some of the markings on a runway surface, their dimensions, and what they represent. Aside from helping you identify the runway on which you are landing, these markings can also help you determine your “float” distance on short-field and power-off 180 landings. There are three types of runways:
- Visual Runways
- Nonprecision Instrument Runways
- Precision Instrument Runways
Each of these runways has designation markings, aiming point markings, and centerline markings. Nonprecision and Precision Instrument Runways have additional threshold markings. Visual runways may contain threshold markings when intended for use by international commercial transports. On top of that, Precision Instrument Runways have side stripes and touchdown zone markings. The crew in the report above also mentioned that they tuned in the runway 23R ILS (a precision approach) to identify the centerline; however, they did not make the connection with the lack of precision approach path markings on Runway 23L, nor did they notice that the localizer needle was displaced.
The table below shows the different elements available for each type of runway.
Runway numbers are determined based on the runway’s heading. The runway number is the whole number nearest one-tenth the magnetic azimuth of the centerline of the runway, measured from magnetic north. The letters L, R, and C represent left, right, or center parallel runways.
The runway centerline identifies the center of the runway and provides alignment guidance during takeoffs and landings. The white stripes are 120 feet in length, while the gaps in between are 80 feet in length. This is important knowledge for pilots attempting to land on a specific point for short-field and power-off 180 landings. Effectively, Private Pilot applicants will have to make a short-field landing touchdown within one stripe and one gap (200-ft. buffer per ACS), while Commercial Pilot applicants will have to make a short-field landing touchdown just under the length of one stripe (100-ft. buffer per ACS). Commercial Pilots attempting to make a power-off 180 landing will have to land within one stripe and one gap (200-ft. buffer per ACS).
Threshold markings help identify the beginning of the runway available for landing. In some instances, the landing threshold may be relocated or displaced.
Runway thresholds come in two configurations:
- Eight longitudinal stripes of uniform dimensions
- The number of stripes is related to the runway width
In the second instance, runway widths may be determined according to the table below.
The runway in this example has twelve stripes, which informs the pilot that the runway width is approximately 150 feet.
Aiming point markings serve as visual aiming points for a landing aircraft. These two rectangular markings consist of a broad white stripe located on each side of the runway centerline, preferably about 1,000 feet from the runway threshold.
Touchdown Zone Markings
Touchdown zone markings identify the touchdown zone for landing operations and are coded to provide distance information in 500-ft. increments. These markings consist of groups of one, two, and three rectangular bars symmetrically arranged in pairs about the runway centerline. Based on these markings, you can infer how far down the runway you have rolled and how much runway is left.
Side Stripe Markings
Finally, we have side stripe markings, which provide a visual contrast between the runway and the adjacent terrain or shoulders. Side stripes consist of continuous white stripes located on each side of the runway and are only found on Precision Instrument Runways, as mentioned above.
We hope the information in this article has made you more aware of the purpose of certain runway markings that are often overlooked. Utilize this knowledge for more precise landings, and identify what runway you are approaching when flying into your next unfamiliar airport. For more information on airport signs and markings, grab a copy of the Gleim Pilot Handbook or refer to Chapter 2 of the Aeronautical Information Manual.
Written by: Ryan Jeff, Aviation Research Assistant, and Paul Duty, Chief Instructor