Using the ITA Route Language to Customize Your Search

The ITA trip request forms allow you to enter basic information for finding solutions to your trip planning needs. However, the page also supports a very powerful query language, called the "Route Language", which permits you to specify exactly which airlines, flight numbers, and connection points are considered for each portion of your trip.

Route Language entries are made in the "From" and "To" fields on the trip request forms. Normally, you simply list one or more airports or cities in these fields; optionally, however, you may also specify a route expression after the airports/cities which contains specific instructions about what routes to consider. The airports/cities are separated from the route expression with two colons, like this:

If you are planning a round trip, specifying a route expression in the "From:" text field will affect the options produced for the outbound portion of the trip; route expressions typed in the "To:" text field affect options produced for the return portion of the trip. In one-way and multi-segment trips, you may enter one route expression in each "From" field only.

Some important definitions

When writing route expressions, it's important to be precise about terminology. As such, it's important to understand the following definitions:

Using route expressions: Some simple examples

Without thinking about it too much, let's see what kinds of things the route language can do:

	Route expressions	Meaning
From:	BOS;PVD :: DFW	Only search for options which depart either Boston or Providence, and which stop in Dallas/Fort Worth airport for the outbound, but which may use any itinerary for the return from Los Angeles to Boston or Providence
To:	LAX
From:	BOS :: AA+	Only search for options which are on any number of American Airlines flights for the outbound, and which uses a single flight on either American Airlines or United Airlines for the return
To:	LAX :: AA,UA
From:	BOS :: N	Only search for non-stop options on any airline for the outbound, and options containing any number of stops on any airline, except for Continental, for the return
To:	LAX :: ~CO

Route Expressions: The Gritty Details

The general form of the route-expression is a series of one or more flight or connection point specifications, each of which can be prefaced with a ~ (indicating the implied test should be negated) or suffixed with a * (zero or more), + (one or more), or ? (zero or one). Commas without spaces between flights or points signify to "or" the expression; spaces between flights or points signify "and." Flights or points are specified by two-letter airline codes, three-letter airport/city codes, or the special characters "N" for nonstop flight, "F" for direct flight (possible stop but no change of planes), and "X" for connection point.

The following table is a list of all legal route expression elements:

If two connection point specifications are listed consecutively, the implication is that any single flight-segment is permitted between them. If two flight specifications are listed consecutively, the implication is that any single connection is permitted between them. The origin and destination are implied, so for a BOS to LAX trip, "STL" implies two flight-segments, from BOS to STL and from STL to LAX. Flight specifications match against flight-segments (sequences of legs with the same carrier and flight-number), no matter how many legs they have.

Negations specified with ~ invert any tests, but not the implied number of events. Thus, "~STL" specifies a connection in a point other than St. Louis, but a connection is required. To make the connection optional but still prevent a stop in STL, use "~STL*" which implies zero or more stops, each in a point other than STL.

The special symbol > may be placed at the start of a route to indicate that the initial location restricts the origin airport, and < at the end indicates that the final location restricts the destination airport. For example, "BOS MSP" indicates an itinerary with connections in BOS and MSP, but "> BOS MSP <" indicates an itinerary with origin BOS and destination MSP (one flight).

More examples

The following sample route-expressions illustrate the power of the Route Language. Each expression is preceded by "BOS ::" indicating that, in each case, the first flight is to originate in Boston.