Airports serving American resort regions can offer a dozen nonstop routes in one season and a handful in another. The pattern reflects how airlines allocate a fixed fleet across a year.
Aircraft are the constraint
An airline owns or leases a set number of aircraft, and each must be assigned somewhere every day. Flying a route means not flying another.
Leisure demand is highly seasonal, so an aircraft that earns well flying to a ski market in February earns poorly there in June.
Rather than leave capacity idle, airlines redeploy. The same aircraft moves between markets as demand shifts across the calendar.
Seasonal routes have low switching costs
Adding a route requires gates, ground handling and staffing, and at small resort airports those are often provided by contractors rather than by the airline.
That makes entry and exit cheap. An airline can serve a market for four months and leave without stranding permanent infrastructure.
Crew bases are the harder part, which is why seasonal routes usually originate at an existing hub rather than at the resort end.
Communities pay to attract service
Resort regions compete for flights, and many offer incentives: fee waivers, marketing support, or minimum revenue guarantees that cover an airline's losses if a route underperforms.
Those guarantees are typically funded by local tourism authorities or business coalitions, on the reasoning that a nonstop route expands the feeder market substantially.
Routes launched on guarantees are fragile. When the support period ends, the route continues only if it has become profitable on its own.
Weather and terrain limit which aircraft can come
Mountain resort airports have short runways, high elevation and terrain-constrained approaches, all of which restrict aircraft type and reduce payload.
Those restrictions mean smaller aircraft, fewer seats and higher costs per seat, which shows up directly in fares.
Winter operations add de-icing, closures and diversions, so airlines build schedules with recovery time and often cap the number of daily flights they will attempt.
What the schedule means for booking
Seasonal routes usually load into reservation systems later than year-round ones, so a nonstop that does not appear in early searches may still be announced.
They also disappear at fixed dates, and a booking made close to the seasonal boundary can be affected if the route ends earlier than expected.
Because capacity is thin, cancellations on these routes are harder to recover from. There is frequently no second flight that day to be rebooked onto.