Air travel and airfares continue to get more complicated, even as average ticket prices continue to decline. Here’s a look at six big trends that you will want to keep on your radar:

1. Legacy carriers unbundle coach fares: American, Delta and United have segmented fares for main coach cabin into very specific product offerings and services. Coach passengers who want more legroom, for instance, can pay to upgrade to an exit row seat. Flyers who can’t afford business class but want more luxury can pay extra for premium economy, which includes a wider coach seat on international trips, more legroom and better meals.

Flyers primarily concerned with price can opt for basic economy seats. American, Delta and United allow basic economy passengers to bring onboard one personal item or bag that will fit underneath the seat. American and United prohibit any luggage that requires use of an overhead bin. Delta’s basic economy luggage policy is the same as its traditional main cabin, which allows for a personal item and one complimentary carry-on bag.

Basic economy ticket holders are not able to pre-select seats and are assigned a seat at check-in. Post-purchase refunds and changes to a ticket, such as paid upgrades for priority boarding and premium cabin access, are prohibited. Flyers with basic economy tickets are the last to board the aircraft.

Airline analysts say basic economy allows legacy carriers to address the growing threat from low-cost and ultra-low-cost carriers.

2. Ticket prices continue to decline: A report from Expedia and Airlines Reporting Corp. found average round-trip coach prices in North America fell 5 percent in 2016 from 2015 prices. That was the third year of the downward trend, and 2017 is expected to see lower fares once again. “For today’s traveler, this confluence of circumstances—more planes, lower prices, more destinations—is exceptional,” said Greg Schulze, Expedia’s senior vice president of commercial strategy and services, in a news release about the report.

3. Mobile bookings predominate: Mobile usage is expected to become the main booking method for passengers—regardless of which booking channel they use, according to Amadeus North America, a leading travel technology company. From the company’s airline industry report: “Customer service via mobile devices, such as check-in and flight-delay notifications, is no longer simply a nice-to-have benefit. It has become an expectation and a differentiator. Airlines must adopt technology that allows them to respond to the ever-connected digital passenger of today’s environment.”

4. Expect more computer outages: Travel delays from computer outages rose in 2016 and that trend is expected to continue, reports the Wall Street Journal: “The industry is running a lot of old systems and operations are getting bigger and more complicated. Southwest, Delta and United all had big meltdowns in 2016. In January, U.S. Customs and Border Protection computers shut down nationwide for several hours, creating long lines.”

5. Loyalty programs lose some luster. Thanks to legacy carriers’ unbundling main-cabin fares, upgrades to first class or premium economy are getting tougher to obtain and frequent flier miles harder to redeem, according to the travel magazine Afar.

6. Regional air service is showing improvement. After years of cutbacks of air service to non-hub cities, regional air service is showing signs of expansion: good news for many second- and third-tier convention cities. Dayton, Ohio, for example, is seeing an expansion of service from PSA Airlines, Inc., one of American Airlines’ nine regional subsidiaries. American reported that the number of revenue passenger miles its regionals flew increased by 3.9 percent to 24.5 billion last year.