Finally, former America West Airlines pilots who now fly for American Airlines (AAL) - Get Report have been given their "Get Out of Jail Free" cards.

But it is likely that some will have to leave whether they want to or not. American said Friday that about 500 of the 1,500 pilots currently based in Phoenix will have to find a new base by summer 2017.

In general, Phoenix-based pilots have not been able to move to other bases since 2005, when America West merged with US Airways, because a lengthy dispute over a controversial seniority ruling froze them in place.

The change follows two key events in September. First, a three-member arbitration panel devised a seniority list for the 15,000 American pilots following the 2013 merger between US Airways and American. Then the airline merged its three flight operating systems, each for a different pilot group.

The events enabled an email to pilots on Friday from Kimball Stone, vice president of flight operations, regarding changes in pilot flight scheduling.

"The moment is almost upon us, and by moment, I mean the first combined vacancy run and mutual bid exchange," Stone wrote. "We've said it before and it warrants a foot stomp -- make sure that any bid you submit is for a job you want more than the one you currently have.

"Given the amount of movement possible over the next few years, there's going to be opportunity for changes in base, seat and fleet, and you don't want to end up somewhere you didn't intend to be," Stone said.

Stone said American's 2017 flying schedule will remain level and the carrier will hire about 750 pilots, including 450 to make up for planned retirements, so pilots who leave Phoenix will have options.

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"Over the next eight to twelve months, you will see a significant change in the A320 pilot staffing in PHX as we work to right-size the pilot positions in that bid status," he wrote. "The plan is to spread those positions throughout the remaining domiciles, gradually decreasing the number of PHX A320 pilots by approximately 500.

"This doesn't change the number of flights operating into and out of PHX, just where the trips are built from," Stone said.

In past years, Phoenix flying diminished faster than the number of Phoenix pilots did, so the airline devised pilot trips to accommodate those pilots. For instance, a Phoenix-based pilot might fly a Phoenix-Charlotte-Boston-Charlotte-Phoenix trip. Such trip schedules will no longer be necessary.

While the 500 Phoenix Airbus A320 pilots will have to find new bases, other pilots may be able to move into Phoenix: American said it will offer a voluntary mutual base exchange option to pilots who can find someone to trade bases. Additionally, a few Boeing 757 positions will be created in Phoenix.

Also, easing the impact, some of the roughly 550 pilots who currently commute to Phoenix may choose a base closer to home.

Nevertheless, "this is obviously the end of an era," wrote Kendall Wood, chief pilot in Phoenix, in a message to pilots. "PHX has been unique in that it has been {America West's} only base (apart from when some of you left for a few years to try out Vegas - then came back).

"We have been able to cultivate a wonderful culture and closeness here over the years," Wood said.

"However, if there has been one question from this base especially since the first merger, it has been, 'When can we capture some of the other flying and how soon can we move?'

"Well, that time has arrived," he said.

This article is commentary by an independent contributor. At the time of publication, the author held no positions in the stocks mentioned.