Fare Rule Glossary

ASC	Circle Trip	Combinability
Co-Terminals	Direct	Discounts
End-On-End	Inventory	Maximum Permitted Mileage
Nonstop	Open Jaw	Open Return
Originating Flight	PTA	Rerouting (Voluntary)
Revalidate	Round Trip	Routing
Segment	Standby	Stopover
TBM	Transfer	Upgrade
Waitlist

ASC
Administrative Service Charge. Usually it's the same as the change fee, or the fee to exchange the ticket for future travel.

Circle Trip
Travel from A to B then back from B to A using different fare basis codes (see also round trip)
--OR--
Any trip involving a stopover in addition to the ultimate destination
(e.g. A-->B, B-->C then C-->A using the same or different fare basis codes).

Combinability
Whenever you are traveling on anything other than a round trip, fare combinations come into play. Combinability refers to whether two or more fares can be combined to construct an itinerary for a given passenger. Types of trips involving combinations include circle trips, open jaws and end-on-end combinations.

A few basic, general principles apply to fare combinations.

1) The most restrictive conditions apply. For example if you are combining a fare that is 50% refundable with one that is non-refundable, the whole ticket becomes non-refundable because the non-refundable rule is the most restrictive. As another example, if you are combining a fare that requires 7 days advance purchase with one that requires 14 days advance purchase, the entire ticket must be purchased 14 days in advance. The same reasoning applies for the minimum/maximum stay, change fees, service charges and other restrictions.

2) It is virtually impossible to sort out all the combinability details yourself. Usually the online reservations system will work out all the details for you. If you need additional help, call your travel agent.

Co-Terminals
Co-terminals are different airports that are equivalent with respect to fare calculation. For example, if FLL - MIA are listed as co-terminals, Fort Lauderdale and Miami would be equivalent airports for fare construction under that particular fare rule. Note that cities may appear as co-terminals for a given fare rule which have nothing to do with the routing between your origin and destination. The fare rule is of a general nature, and fares may be offered between many different city pairs under the same fare rule (e.g. a seat sale).

Direct
Used to describe a flight from A to B with the same flight number and no change of aircraft. May have one or more stops. Compare with nonstop.

Discounts
Fare rules will commonly refer to three types of discounts: infant, child and senior. Infants under 2 usually fly free on domestic flights provided they do not occupy a seat. Some fares offer children's discounts, generally for children aged 2-11. Deeply discounted seat sale tickets may not offer a further discount for children. Many airlines offer senior citizen discounts, and some also offer discounts for a companion traveling with the senior citizen, even if the companion is not themselves a senior citizen. Different airlines have different age definitions of senior - check with your airline.

End-on-End
A special type of combination in which two round trip fares are combined to produce a complete itinerary.

From To Rule

AAA BBB Rule 1

BBB CCC Rule 2

CCC BBB Rule 2

BBB AAA Rule 1

In this example, the passenger buys a round trip ticket from AAA to BBB (Rule 1), and a separate round trip fare from BBB to CCC (Rule 2). The net effect is to travel from AAA to CCC, but breaking the fare at BBB, which may in some cases be less expensive than the round trip (through) fare from AAA to CCC. Fare rules usually specify whether end-on-end combinations are allowed. Sometimes end-on-end combinations can be used as a "trick" for finding low fares online.

End-on-end combinations are very different from back-to-back ticketing, which is expressly forbidden by most airlines.

In March 2016, American, United and Delta restricted the ability to combine certain non-refundable fares end-on-end. The language in the fare rules said something like:

END ON END MUST BE AN A-B-A COMBINATION

In other words, if you were flying LAX-ORD-LAX, you could combine two different fares for each segment, but if you were flying LAX-ORD-EWR, you could no longer use two different non-refundable fares containing this new restriction. Note that the number of non-refundable fares containing this restriction has been reduced since it was first introduced.

Inventory
Inventory is another word for available booking classes (e.g. F,P,J,C,Y,M,B,Q,H,V,L, etc.). You may see a phrase in the fare rules like "INVENTORY MUST BE AVAILABLE FOR FARE TKTD" - often in the section on Rerouting.

Maximum Permitted Mileage

This section (MPM) was written by Yusuf Sunar.

In general, international fares are based on mileage and North American fares are based on routing. In the international fare tariffs there is an established amount of mileage called the maximum permitted mileage (MPM) between every point A and B. The carriers interested in the traffic between these points A and B, can use their own hubs to fly this traffic provided the maximum permitted mileage is not exceeded. In the event that the mileage is exceeded, a surcharge of 5%, 10%, 15%, 20% or 25% can be assessed for an additional 5%, 10%, 15%, 20% or 25% mileage, respectively. Beyond 25% additional mileage, the through fare must be broken.

In the MPM system backtracking is not prohibited, however there are certain other restrictions in place, such as:

The point of origin or the point of destination cannot be used as an intermediate point in the same fare breakdown (i.e. the following examples would not be allowed: YYZ LON PAR ZRH FRA ZRH or BKK SIN HKG BKK LAX YYZ)

You can travel via the same intermediate point more than once but you can only stop once (i.e. the following would not be allowed: YYZ LON PAR FRA PAR ATH (stopping in PAR twice would require a side trip PAR FRA PAR))

In some fares such as round the world fares, the rules state that travel must be in the same global direction, thus preventing backtracking.

Nonstop
Used to describe a flight from A to B with no enroute stops. Compare with direct.

Open Jaw
Travel from A to B then from C to A, with no air ticket from B to C.
Usually the distance BC must be less than both AB and CA (i.e. the part without the air ticket must be shorter than the shortest distance flown).

Open Return
An open return is a ticket valid for transportation between the destination city and the city of origin with no set date or flight. Many fares do not allow open returns. The rules might say so explicity, or you may see something like "segments using this rule must be confirmed", which means no open return and no waitlisting.

Originating Flight
The first flight on your ticket is your originating flight.

PTA
PTA stands for prepaid ticket advice. This option allows someone other than the passenger to pay for the ticket, even if the payer is in a different city. The passenger then picks up the ticket from the airline or the travel agent in the passenger's city. Sometimes a fare rule states "PTA satisfies ticketing requirements", indicating that once the PTA is arranged, even if the ticket is not physically issued, the requirements for ticket issue (e.g. within a certain number of days after reservation and before departure) are met.

Since the advent of electronic ticketing, PTA is used far less commonly. Electronic tickets are a much better way to handle this situation. Usually the airline charges a fee for processing a PTA, unlike for electronic tickets.

Rerouting (Voluntary)
If, before departure, a passenger wants to make a change to their itinerary, we call that voluntary rerouting. The term rerouting may be confusing, in that the actual route does not have to change (although it could) - i.e. any change to flights, dates, times or destinations are considered rerouting.

First, consider some background. Recall that in the Penalty section of Fare Rule Basics, I said that certain conditions would apply to the ability to change a ticket for the change fee (e.g. $100). The rerouting rule describes conditions under which the itinerary can be changed for only the change fee.

The underlying principle is to provide the passenger with some degree of flexibility while at the same time not being unfair to passengers who have paid much higher fares (e.g. Full Coach) for maximum flexibility. For example, suppose a business traveler bought a full coach fare from New York to L.A. for $1680 return. She did so to provide maximum flexibility. Suppose also that a college student bought a ticket on the same route for $318 return. If the college student could make any changes he wanted for only $50 with no additional restrictions, then why would the business traveler pay $1680? As you will see, the rerouting rules attempt to be fair to both parties.

Rerouting rules usually are different before departure and after departure.

Before Departure...New Fare Required
At the time the passenger wants to make a change to his/her originating flight, the passenger becomes subject to the fares in effect on the date the change is made for travel on the dates desired. In other words in effect the passenger is making a new reservation, and is subject to all of the rules of the new fare, including advance purchase requirements, ticket purchase deadlines and minimum/maximum stay requirements. The new itinerary must usually be of equal or higher value than the original itinerary. The passenger must pay the difference between the original fare and the new fare PLUS the administrative service charge (e.g. $100). If the new fare is of lower value, you may get a refund, a credit for future travel, or neither, depending on the fare rule.

Suppose that today is March 25 and several weeks ago a college student living in New York bought a round trip ticket to L.A. with a departure date of April 1. The student now wants to leave March 26 instead of April 1. The only applicable fare at this time may be a Full Coach fare. The student would then be required to purchase a full coach fare, but he/she could use the value of his/her special fare ticket towards that purchase. The original non-refundable amount remains non-refundable. In other words one cannot "get around the system" by upgrading a discounted ticket to a full fare ticket and then getting a full refund for the full fare ticket as a way to in effect get a refund for an unused discounted ticket.

After Departure...Don't Forget to Enjoy your Saturday Night Stay
One major difference is that after departure voluntary rerouting is not permitted except to the dates/times of your flights. That is, once you have departed from New York to Los Angeles, it is now too late to change your itinerary and decide to stop in Indianapolis on the way home. (At least, it's too late to do so using any credit from this fare. It's never too late to do whatever you want if you're willing to buy a new ticket!) You can change the day or time you are traveling, provided that you don't change the origin/destination/stopover points, that the change meets the minimum and maximum stay requirements of the original fare (you can't cheat and come back before the Saturday night has passed), and that applicable inventory (e.g. M class) is available on the new flight.

If the inventory (booking class) at the original fare is not available, changes can be made to change the return to any combinable fare (not all fares are combinable with each other - see the section on Combinations). For example, if M class is not available, K class can be booked on the return, provided that the restrictions mentioned apply. The difference in the fare would have to be paid as well as the applicable service fee (e.g. $50).

As another alternative if the applicable inventory is not available, you may be able to standby at the airport. Check with your airline for details.

Revalidate
Generally airline tickets are valid for one year from date of issue. If the airline were to revalidate a ticket, its value could be extended beyond one year. Some fares specifically exclude revalidation.

Round Trip
Travel from A to B then back from B to A using the same fare basis code. See also circle trip.

Routing
The routing rule lists the allowed connecting cities for travel from A to B for a particular fare. Sometimes this rule indicates that travel must be nonstop.

Segment
A segment refers to a single flight with the same flight number. For example, if you travel from A to B, change planes at B, and then travel from B to C, you will have flown two segments. On the other hand, if you travel from A to C and the flight stops at B, but you don't change planes, then your trip from A to C is one segment from the point of view of fare rules. Note that the US federal segment tax defines both of these scenarios as two segments.

Standby
Standby allows a traveler to wait at the gate for a seat to become available, usually minutes before a flight departs. Some fares which otherwise require a change fee allow passengers to standby for earlier or later flights on the same day at no additional cost. See also waitlist.

Stopover
Suppose you were flying from New York to Los Angeles, and you wanted to stop and visit your aunt in Indianapolis on the way. Such a visit would constitute a stopover in Indianapolis. Some fares allow free stopovers, others allow stopovers for an additional fee, and many fares do not allow stopovers at all. Now, your flight might be routed through Indianapolis anyway, and you might even have to change aircraft there. You might think you could "beat the system" by booking a connecting flight for the next day. You usually cannot do so, since if you do not depart your intermediate point (Indianapolis) within 4 hours of your arrival there, it would normally be considered a stopover. Therefore, such an arrangement would not be allowed if the fare did not permit stopovers.

Three important notes:
1. A connection in Indianapolis would be allowed provided that the time between flights was no greater than 4 hours. If your aunt wanted to come out to the airport to have coffee with you, this rule would not prohibit that. (An additional proviso is that Indianapolis must be on the fare routing. You can't say that Los Angeles is on the way from New York to Miami and book a connecting flight through Los Angeles at no extra charge!)

2. You may still be able to stay over in Indianapolis for a few days using this fare if booked as a circle trip, rather than a stopover. See circle trip for details.

3. Generally speaking the 4 hour rule applies provided that there is a connecting flight departing within 4 hours. For example, if there is no connecting flight for 6 hours, then it is usually valid to take that flight and still call it a connection rather than a stopover.

TBM
TBM refers to Ticketing by Mail, meaning that one can order tickets from the airline to be sent in the mail.

Transfer
A transfer is a connection enroute from origin to destination.

Upgrade
While most of us think of an upgrade as an opportunity to sit in First/Business class, in the world of fare rules an upgrade means something entirely different. An upgrade refers to changing your ticket to a higher fare for the same or different flights. The higher fare may still be in coach, but you may be required to upgrade if you want to make a change that does not meet the conditions of the change fee for the lower fare. See example in Rerouting.

Waitlist
Some fares allow a passenger to be put on a waiting list for the required booking class if it is sold out. Usually the deeply discounted seat sale fares do not allow waiting lists, but intermediate and higher fares usually do. A waitlist refers to making reservations only, and it has nothing to do with the standby list at the airport. You cannot usually add yourself to a waitlist using online travel reservations - call the airline or your professional travel agent.