Wonderful Engineering

Ever Wondered What Those Numbers On A Airport Runway Mean? Here’s All You Need To Know

Airports everywhere keep on changing the name of their runways. This is not because the styles are changing continuously or the rules and regulations keep on changing, but because the earth’s magnetic field keeps on shifting. It may not sound like it but the continuous replacement of airport signs and repaints costs hundreds of dollars every time. The reason behind this constant change is that the magnetic North Pole moves as much as 40 miles per year. This extreme variability brings problems for pilots and airports since the runways are named on the basis of how many degrees off north they are.

Wichita’s 14/32 runway can be used from either direction. It is either 140 degrees from the north or 320 degrees in the other direction. These numbers are rounded to the nearest ten and then shortened two digits. This is an easy way for pilots to make sure that they are landing and taking off from the correct strip. However, the earth’s magnetic fields complicate this easy system. The FAA orders airports to change the runway names once they have changed to an extent that they no longer round to the same figure. For instance, a runway that is named 36 will not have to change its name if the degrees off north went from 355 to 359. But when it goes to 354, the number needs to be changed to 35.

This process is currently happening at the Wichita Eisenhower International Airport. Runways 1L/19R, 1R/19L. The numbers refer to parallel runways and the R and L represent the left and right. the 14/32 will be changed to 2L/20R, 2R/20L and 15/33. After 1954, this is the first time the runways will be renamed. Many times, the distinction doesn’t even matter much since the pilots can visually identify the correct runway. But mislabeling can also cause serious consequences like the 2006 Comair Flight 5191 crash in Lexington, Kentucky. The crash killed 49 people. The investigation on the case revealed that the crew couldn’t correctly identify the runway and took off from the shorter runway that resulted in the crash. Keeping up with the constantly changing magnetic fields might be a bit of a pain and extra effort, however, as long as it is keeping the flights safe, it is worth all the effort.