Just because you're not paying cash for your flight doesn't mean you can't be picky about the type of plane you fly. Some of the world's largest airlines have a dozen or more different aircraft types in their fleets, with onboard amenities and comforts differing tremendously from plane to plane. You'd probably recognize the iconic 747, with its upper deck, vast wingspan, and four huge engines, or the new Airbus A380, which many aviation enthusiasts liken to a flying whale (admittedly, it's a little ugly).
But what about the little guys? Is there any reason to choose an Airbus A320 over a Boeing 737? With certain carriers, absolutely.
If you travel often with the same airline, you'll start to pick up on which planes offer which perks. On United, you'll find DirecTV on a 737 and flat-bed seats on certain 757s, but you won't get both features on both planes. Even the airline's wide-body planes (with two aisles in the cabin), which are typically associated with more comfortable (or at least entertaining) long-haul flights, have different seats and entertainment options on board. All on United's 767s and most 777s sport on-demand seat-back TVs throughout all classes of service, for example, but the 747 offers only overhead TVs in coach.
What the Airline Offers
To stay ahead in the confusing world of mixed fleets, it's important to familiarize yourself with your airline's products. Each carrier's website typically lists the planes you can fly and what you'll find on board. In First Class and Business, that can mean anything from tightly positioned recliner seats or private suites, while in coach, you can find different seating densities (the number of seats the airline can fit in each row), power outlets and seat-back TVs. Passengers in all cabins should also be on the lookout for in-flight WiFi, which airlines offer on some planes but not others.
On American, you may find a wide-body 767 scheduled for a flight from New York to Miami, while the same plane type may be assigned for Atlanta to Minneapolis on Delta or Chicago to San Francisco on United. Airlines might have dozens of flights scheduled between these cities each day, but only one with a large internationally configured plane. If you select the correct flight, you could be traveling in a much more comfortable aircraft, with free movies and better seats, for the same number of miles.
There can be other advantages to picking a wide-body plane for a domestic flight, too. These aircraft are typically assigned to long international flights later the same day, with destinations that the airline only serves once daily. In inclement weather, your carrier may avoid canceling the domestic leg if it's being used to position the plane for an international flight. For example, if United has a 767 scheduled for Houston to Newark early in the day and Newark to London that evening, the airline may cancel its smaller 737 and A320 flights between Texas and New Jersey during a snowstorm, while the 767 will still fly, as to avoid stranding international passengers in Newark or at a foreign destination.
How to Find Flights
To figure out which planes are scheduled for which flights, check your airline's website or the third-party booking tool you're using to price out a trip. Most sites list the aircraft type with other details, and if the airline flies several configurations of each plane, you can usually sort which amenities you'll find on board by looking for WiFi, on-demand movie or flat-bed seat indicators in the airline's booking tool. If you don't have luck there, try matching the seat map against the airline's fleet info page.
United's 777 with two seats on each side and five in the middle is the older configuration, for example, while the variant with three seats in the center and at both sides has the newest features on board.