FLY 110 - Segments, Legs, Trips, and More

In this lesson we cover trip segments; what they are called and how they are related.

Content Index

  • IATA Codes - Airports and Airlines.
  • Segments, Legs, Trips
  • Connections, Layovers, Stopovers, Surface Legs/Segments
  • Open Jaws, Double Open Jaws, Round The World.
  • Codeshares, Interline, Space Available

Links and Resources

IATA Airline and Airport Codes

IATA is a trade authority over the world's airlines and manages the codes used to identify an airline or an airport. Airlines have a 2-digit code and airports have a 3-digit code. When you search in most flight booking search engines you can use the city name, or you can use the airport code.

Here are the main ones (West to East):

  • Vancouver (YVR)
  • Calgary (YYC)
  • Edmonton (YEG)
  • Toronto (YYZ)
  • Montreal (YUL)
  • Halifax (YHZ)

Click here for a full list of all Canadian Airports and their airport codes. 
Or Click Here for all Airports in the World!

Here are the main airlines servicing Canada and their codes:


  • Air Canada (AC)
  • Westjet (WS)
  • Porter (PD)
  • Air Transat (TS)
  • Full List


  • American Airlines (AA)
  • United Airlines (UA)
  • British Airways (BA)
  • Delta (DL)
  • Alaska Airlines (AS)
  • Full List

Segments, Legs, Trips

These words have very different definitions depending on who you ask. For now though, let's keep it simple. For these examples, let's use a sample trip; a round trip flight from Vancouver to Toronto that has a layover in Calgary on the way out and also on the way back.

Outgoing Trip = YVR-YYC-YYZ
Return Trip = YYZ-YYC-YVR


Segments are between Origin and Destination. If your Origin is Vancouver and your destination is Toronto, it's fair to say that no matter how you get there, the journey from YVR to YYZ is one segment if you booked it on one ticket and didn't have a long stop along the way.

YVR-YYC-YYZ = 1 Segment

Segments also have another meaning when you are talking about qualifying for frequent flyer (FF) loyalty status with an airline. For now let's just keep it simple but be aware if you see segment in relation to a "Qualifying Segment" then it usually refers to some sort of FF program.


Legs are between airport to airport, take-off and landing. So if your Origin is YVR and your flight takes you through YYC to then get another flight to your destination, YYZ. Then you have 2 legs in this journey.

YVR-YYC = 1st Leg
YYC-YYZ = 2nd Leg
YVR-YYC-YYZ= 1 Segment with 2 Legs

If there was another stop in Winnipeg or something it would be 3 legs - YVR-YYC-YWG-YYZ. 4 airports, but only 3 flights to get between them so 3 legs.


Trips we will refer to as a single booking/ticket. So if you buy a Round Trip from Vancouver to Toronto through Calgary, it would be:


If you bought two separate one way tickets, it would be:


Technically two trips in terms of completely separate bookings/tickets. A booking can have all kind of variations on this, but the point is that sometimes your booking is classed as one trip (altogether on the one booking), other times you might have to separate it and make it two. This will become clear later.

Connections, Layovers, Stopovers, Surface Transfers

Domestic Layover

Connections and Layovers are usually the same. In normal speak, when you have to get off the plane and wait in a random airport for a bit until your next flight to your destination. There's funny rules about how long a layover can be on domestic or international tickets. Here is the general rule:

International Layover

  • Domestic = 4 hours
  • International = 24 hours

It's not always consistent but the point is that layovers on flights do not cost anything. Like the airline can't charge you an extra $100 just because you had an additional airport on your trip. On international flights, some airlines even give you hotel hookups.

If these layover times were unrestricted people could have awesome holidays in multiple places on one ticket (and some people do!) but for the most part the airlines want to avoid this. So they made the 4 and 24 hr rule. Technically, if a ticket you find has a longer layover, it just means that it is priced as two separate tickets on the one trip. As such, depending on the tickets available, it could be a lot more expensive, or super cheap due to weird inconvenient times. It's a little complicated, but for now just know that layovers are free.

Stopovers are not always free! Sometimes they charge you extra if you want to route through a certain airport. In the Fare Rules of many tickets, there are provisions for how much an extra stopover will cost. All you need to know is that a stopover is usually outside the 4 and 24 hour rule and they are cool because they let you stay in a location for a while, and usually the benefit is that it is on the same ticket, which could make the whole trip a lot cheaper.

QuestOrganizer is a flight booking site that lets you plan trips with stopovers. Pretty cool.

Surface Transfers are when you have to change airport over the land. It is rare, but it does happen. You may be flying into New York JFK airport, but your flight flies out of New York La Guardia Airport. Other times you might be on an open jaw ticket say from Toronto to Halifax but you want to go see your friend in Montreal before you fly home to Toronto. Sometimes this can result in a cheaper ticket, especially if you find a cheap bus ticket between Halifax and Montreal! You will need to book your own bus or ferry or a completely separate ticket to get between airports though.

Open Jaws, Double Open Jaws, Round The World.

Above we went over simple trips like one way journey to Toronto, round trip journey, etc. Now we get to some more complicated stuff.

Open Jaw

An Open Jaw is called an Open Jaw because it looks like a jaw that is open. haha. A nice way to remember.

Open Jaw trips are when you are taking two flights, but there are 3 destinations involved. Like if you went from Toronto to Halifax for a birthday, but wanted to fly to Montreal afterwards for exams. The 3 destinations are Toronto, Halifax, and Montreal, all booked on the one ticket.

An Open Jaw can be either of the following:

  • Type 1 - The First Destination you go to is the common point or the "Jawbone" of the trip. You are returning to a different airport than the one you started at. YVR-YHZ, YHZ-YUL.
  • Type 2 - The Origin is the "Jawbone". You have to somehow get from YHZ to YUL because the ticket is an Open Jaw

Type 1 - Destination Jawbone. Start in YYZ. Finish YUL.

Type 2 - Origin Jawbone. Start in YYZ, finish YYZ.

Why would anyone do this?! Well because sometimes you might need to see two cities in one ticket. Other times, flights to a city might be cheap, but flights back are really expensive. So by using a bus or something else to surface transfer, you can save money. Other times, it might just be cheaper to buy the open jaw and have to take the bus or train or hitchhike or whatever.

Double Open Jaw

Double Open Jaw

Double Open Jaw is like an Open Jaw but there are 4 destinations and there is no Jawbone!

Why would you do this?! Because again sometimes it suits your plans, and sometimes it ends up being a lot cheaper. The thing to take away is that its always worth a try to get it on the one ticket if you have multiple destinations to visit.

Round The World

A Round the World ticket is usually just a series of One Way tickets. It is cheaper because they are their own set of tickets. More on Round the world tickets in another series.

Round the World Ticket

Codeshares, Interline and Space Available

Multiple flight numbers for sameflight.

Codeshare is when the same flight has 2 or more different airline's flight numbers on it. This is due to agreements between the airlines so they can reduce the cost. They usually occur from Major hubs with international airlines. There is often an "Operating Carrier" airline (sometimes referred to as "Whose metal/plane are they using") and the other airlines are just selling seats on that flight. For example if you flew from Vancouver to Manchester in England on Air Canada. Air Canada doesn't fly all the way to Manchester on their own, but they fly to London, and then they just get another airline to take you to Manchester. To avoid confusion they would keep an Air Canada flight number on the flight so people still know it's Air Canada involved. All in all this is not hugely important except to know why a flight might have multiple flight numbers. And also to remember that not everybody on that flight will have paid the same amount of money!

Interlining is when one ticket/trip might be on multiple airlines. Some airlines have agreements so that they can ticket on behalf of them. Like if you fly to South America on United it might go through San Francisco then to Panama. But United doesn't fly out of Panama to South America. However, they have an interlining agreement with COPA airlines and so they can still issue me a ticket for that flight on COPA. Otherwise I would have to wait until I got to Panama before I could get my ticket. This is mainly useful to know that Airlines have agreements with each other that allow you to have tickets all the way through to your destination. It also means you could be flying multiple airlines in one trip, even though you booked on one particular airlines website, or whatever.

Space Available is technically just Standby Travel by employees of airlines. Sometimes airline employees get perks like a "Buddy Pass" where they can give someone the ability to 'standby' for a flight. Standby means you book yourself on the flight as a "maybe". You are waiting at the gate and if there are seats left on the flight then you can get on, but if there aren't, then you have to wait for the next flight or go somewhere else. These are usually a fraction of the cost of a normal flight depending on which airline you work for. They are a great perk. But it is ultimately an unpredictable guessing game as sometimes the flight has no seats left then somebody misses their flight so the employee or "buddy" gets to go in their place. It's a rough way to travel but super cheap.