A charter airline is one that operates charter flights, that is flights that take place outside normal schedules, by a hiring arrangement with a particular customer.

In the context of mass tourism, charter flights have acquired the more specific meaning of a flight whose sole function is to transport holidaymakers to tourist destinations. Such charter flights are contrasted with scheduled flights, but they do in fact operate to regular, published schedules. However tickets are not sold directly by the charter airline, but by holiday companies who have chartered the flight (sometimes in a consortium with other companies).

Although charter airlines typically carry passengers who have booked individually or as small groups to beach resorts, historic towns, or cities where a cruise ship is awaiting them, sometimes an aircraft will be chartered by a single group such as members of a company, a sports teams, or the military.

Many charter flights are sold as part of a package holiday in which the price paid includes flights, accommodation and other services. At one time this was a legal requirement (or one enforced by the airlines' cartel), but this is no longer the case, and so-called "flight-only packages" can be bought by those who merely want to travel to the destination. Such packages are frequently cheaper than regular schedule airline fares. Furthermore charter airlines frequently operate on routes, or to airports, where there is no scheduled service. Much of the traffic through small and medium sized airports in the United Kingdom consists of charter flights, and the survival of these airports often depends on the airline landing fees they get from the charter companies.

Many airlines operating regular scheduled services have set up charter divisions, though these have not always proved competitive with the specialist charter companies. In addition, some cargo airlines occasinally carry a few charter passengers on their jets. Conversely, some charter airlines have branched out into scheduled services when their charter operations have uncovered a need or a market niche.

The economics of charter flights demand that the flights should operate on the basis of near 100% seat occupancy, and the standard of seating and service may be lower than on scheduled airlines (though this is by no means always the case).

The airlines operating charter flights, and the holiday companies who are the initial purchasers of seats on them, have acquired an unhealthy reputation for financial instability. There have been a number of high-profile cases where holiday-makers have had their arrangements cancelled at short notice (and sometimes lost the substantial sums they have paid for package holidays), or have been left stranded at their destinations, by the collapse of airline or holiday company. A number of compulsory insurance and bond arrangements have been put in place to minimise at least the financial risk to the public from such events.

Charter operators

Among airlines who offer or have offered charter services are:

Popular charter airline destinations include Palma De Mallorca, Tenerife, Alicante, San Juan, Honolulu and Miami.