A study of texture on airport runways using an outflow meter and the sand patch method

Hundreds of aircraft take off and land safely every hour of the day, all over the world, without incident. From the perspective of the average consumer, what matters most is getting from point of origin to point of destination in a timely and safe manner. The makeup of a runway plays a major factor in landing an aircraft safely. But what does it take to accomplish this goal? A good pilot, a good airplane, good engines, clean fuel, good tires, and good brakes are some of the components.

Another lesser-known but vital factor is runway texture. Texture is a major component in ensuring safe landings, and maintaining the proper texture involves regular examination and maintenance.

Two airports, San Antonio International Airport (SAT) at San Antonio, Texas, and Laredo International Airport (LRD) at Laredo, Texas, were utilized in this experiment for different reasons. The airport in San Antonio was selected because at the present time, SAT operations has only one method of inspecting the airport's runways, and this method involves using a skid friction tester. On two separate occasions, skid friction testing was observed at SAT. Only after witnessing the procedures and interviewing several SAT personnel did it become apparent that SAT depends on this method exclusively. Realizing this fact was the motivation to look for a viable alternative method that would serve as a backup for the maintenance personnel at SAT.

Laredo International Airport was chosen because it has neither antiquated nor modern testing equipment; instead, it employs a simple visual inspection despite the fact that, on some days, it handles more takeoffs and landings than the San Antonio facility. After interviewing personnel, the consensus was that finding a viable alternative testing method was warranted. Since LRD is undergoing changes, the operations manager at the Laredo International Airport was enthusiastic about conducting experiments with alternate testing methods in keeping with LRD's goal of maintaining the best runways possible. For this study, the alternative methods to measure texture on runways were determined by considering cost and ease of implementation. The two methods chosen for testing were an outflow meter and the sand patch.

Overall, both provided favorable results but the sand patch method proved to be more reliable and accurate in determining texture.