Why Alaska Airlines is changing how its registers its planes

 Look for new registration numbers on Alaska's fleet. Photo: Alaska Airlines. 

Look for new registration numbers on Alaska's fleet. Photo: Alaska Airlines. 

For five decades, all Alaska Airlines registrations followed the same pattern. The airline used three different numbers and the same two letters - AS. According to the airline, the 'AS' refers to the carrier's initial name, Alaska Star Airlines. [It dropped the 'star' in 1944.]

"The tradition of using AS in aircraft registrations appears to have started with Alaska’s first Boeing 727, N797AS, that was delivered in October 1966," Alaska said in a blog post last week. "The current fleet has grown to 152 Boeing 737s, all with AS in the registration number."

But the times are changing. 

In the post, Alaska said it is switching its 'N number' convention. Instead of AS, it is now using AK. The first plane with the new designation arrived in mid-April, a Boeing 737-900ER registered as N224AK.

Why the change?

Alaska said the FAA, which does out registration numbers, is nearly out of AS designations. Alaska says only seven 'AS' numbers remain, having been taken by other operators, like Florida's AirScan, which registered a Cessna 337 as N945AS. 

"FAA registration numbers are similar to a car’s license plate," Alaska said in the post. "In the U.S., each civilian aircraft’s registration number starts with N followed by five characters. Anyone can reserve personalized number/letter combinations – and Alaska doesn’t have exclusive rights to AS."

In addition to other carriers seeking 'AS,' there's another problem. In its post, Alaska said the 'N number' stays with an aircraft even after it leaves Alaska's fleet, so some used planes may still carry the AS registration. Only when those planes are retired can Alaska recover the number -  if no one else takes it first.  

"N945AS was on an Alaska MD-83 from 1990-1997," Alaska said in the post. "Alaska got rid of the aircraft, but the registration lived on as the aircraft flew for AeroMexico until 2005."

Alaska says the FAA has more than 350 unused N numbers with the 'AK' suffix, so the carrier should be in good shape for the foreseeable future.

"Considering our airline growth, and understanding we were running out of AS registrations, we searched for a new, meaningful set of trailing letters and settled on AK – the two-letter code for the State of Alaska,” Russell Summers, manager of aircraft acquisitions, said in the post. 

If you're wondering, all planes that now have the AS designation will keep it.