Advance Purchase: An airfare that requires that the ticket be purchased a minimum period of time prior to departure date.

Airline Identifier: Airlines are identified using a two-letter system. Examples: American Airlines is AA, Southwest is WN, Delta is DL.

Blackout Period: Specific dates, usually around holidays, that a discounted or promotional airfare is not offered.

Boarding Pass: A document attached to a ticket, which permits the passenger to board the aircraft and claim a specific seat. Not all airlines issue boarding passes.

Bumping: The practice of denying boarding to a confirmed passenger on an overbooked flight.

Capacity-Controlled Fares: A limited number of airplane seats to which a special fare has been assigned. This percentage may change depending upon how quickly seats are selling on the flight.

City Code: A three-letter designation given to airport cities.

City Pair: Departure and arrival cities.

Connecting Service: This is the heart of the hub and spoke system. For example, you depart Tucson on Continental Airlines with Cleveland as your final destination. Since Tucson does not have nonstop service to Cleveland, you will stop at Continental’s hub in Houston, deplane and then board another aircraft that will take you to Cleveland.

Direct Service: Also called a through flight, this term is frequently confused with nonstop flight. A direct flight is one that departs point A, stops at point B (almost always a hub), and continues to point C using the same flight number for the entire trip from A to C. If you book a direct flight, you will stop along the way, but you will not change aircraft.

Double Booking / Duplicate Booking: Two reservations for the same traveler on the same day or on overlapping dates. Airlines will cancel both reservations if they discover a duplicate booking.

FIDS: Flight Information Display System. Located in airport terminals to display arrival and departure information. You can see up to the minute FIDS information at the Tucson International Airport by clicking here.

Hub: There are thirty-one designated large hub airports in the United States. Airlines use hubs to transfer passengers between city pairs.

Hub and Spoke: Sometimes referred to as a network system. Hubbing allows airlines to carry large numbers of people originating at spoke cities more efficiently by connecting them at a central hub. Examples are American Airlines’ hub at the Dallas/Fort Worth Airport, and America West’s hub at Phoenix Sky Harbor.

Load Factor: Generally refers to the percentage of occupied seats on an aircraft and can also be expressed as the ratio of revenue passenger miles (RPM) to available seat miles (ASM).

Mainline Aircraft: Generally a medium to long haul airliner such as the B-737, MD-80, A-320 and larger.

Narrow-Body Aircraft: An airliner with a single aisle in the passenger cabin.

Non-Endorsable: A ticket which is not valid for travel on another carrier.

Non-Refundable: A ticket, which cannot be returned for cash or credit if unused, but may be changeable for a fee.

Non-Stop Flight: A flight that proceeds directly to the final destination without any stops at intermediate points.

Non-Transferable: A ticket issued in a particular name that cannot be used by another passenger.

No-Show: A traveler who does not appear for a flight on which he or she has a reservation and fails to cancel that reservation properly. Airlines will cancel all further flights on a traveler’s itinerary if a reservation is not cancelled.

Open-Ticket: A ticket valid for a travel between specified points without a reservation or a specific flight number.

Overbooking: The practice by the airlines and hotels of confirming more seats on an aircraft or rooms in a hotel than are actually available. Overbooking is designed to protect the airlines and hotels from no-shows.

Passenger Coupon: The last coupon of an airline ticket. The coupon is clearly marked and serves as the passenger record for expense reports.

Penalty Fare: A fare that carries a penalty for any changes or cancellations once the ticket has been issued. Penalties can range from a dollar amount to a percentage of the ticket's value to the total loss of the value of the ticket.

Prepaid Ticket Advice (PTA): Authorization number (document) used by the travel agency to ensure that a fully paid ticket is awaiting the passenger at the airport. Airlines impose a non-refundable service charge in connection with the issuance of such tickets.

Promotional Fare: An airfare introduced to increase an airlines market share or to promote service to a particular destination.

Re-issue: Re-writing of an existing ticket due to a change in fare, class of service, or routing.

Restricted To Airport Check-In: Aircraft seat assignments and boarding passes, which can only be secured at time of airport check-in.

Revalidation: A sticker applied to a ticket indicating a change of date and/or flight number but retention of the original routing.

Standby: A traveler who does not have a confirmed reservation and must wait at the airline gate for a seat to become available.

Regional Jet: Small passenger jets with seating for 35 to 80 passengers. These aircraft are in large-scale use by regional “feeder” airlines to supply service over shorter ranges between airline hubs and spoke cities.

Web Fare: Fares that are offered only via the Internet.

Widebody: An airliner with more than one aisle in the passenger cabin.