How to Read a Flight Itinerary: Connections, Layovers, and Codeshares Explained

A flight itinerary is more informative than it looks — and more confusing than it should be. Understanding what each piece means helps you spot problems before they happen and make smarter booking decisions.

The Basic Structure of an Itinerary

When you book a flight, the itinerary shows your journey in segments. A segment is one flight: one takeoff, one landing. A simple round-trip might show:

Segment 1:  YYZ → CDG  |  Dep: 21:30  |  Arr: 11:15+1  |  AC870
Segment 2:  CDG → YYZ  |  Dep: 13:00  |  Arr: 15:25     |  AC871

The +1 after the arrival time means you land the next calendar day. This is common on overnight transatlantic flights and is nothing to worry about — it is just math.

Flight Numbers and What They Tell You

Every flight has a carrier code and a number. AC870 means Air Canada flight 870. The first two letters identify the airline:

• AC = Air Canada
• WS = WestJet
• PD = Porter
• F8 = Flair

Numbers alone do not carry much meaning for passengers, but they are how airlines and airports track specific flights. If you need to check the status of your flight, search by flight number.

What Is a Codeshare Flight?

A codeshare is when one airline sells seats on another airline’s aircraft. The ticket number says one airline, the plane says another.

For example, you might book Air Canada flight AC6044 and find yourself boarding a Lufthansa aircraft. Both airlines share that route — one operates it, the other sells it.

Why this matters:

• Luggage rules may follow the operating carrier, not the selling carrier
• Loyalty miles may credit differently depending on which airline you have a number with
• When there is a problem, it can be unclear which airline is responsible

Your itinerary should say both the “Marketing carrier” (who sold you the ticket) and the “Operating carrier” (who actually flies the plane). Always check this.

Layovers vs. Connections

These terms are often used interchangeably, but they are different:

Connection: A short stop between flights where you stay in the airport. Typically under 4 hours. You usually do not need to re-clear security or customs on domestic connections, though international connections may require clearing customs at your connection city.

Layover: A longer stop, sometimes intentional (you have a few hours to explore the city) or forced by the schedule. Flight search engines typically show anything over 4–6 hours as a “long layover.”

Stopover: A planned overnight stop, often used deliberately to break up a long journey or visit two cities on one trip.

Minimum Connection Time

Airlines build in minimum connection times at each airport — the shortest time that is operationally safe to connect two flights. At Toronto Pearson, the minimum is typically 45–60 minutes for domestic, and 60–90 minutes for international.

If an airline sells you a connection tighter than its own minimum connection time, they are responsible if you miss the second flight because of a delay on the first. If you booked the two flights on separate tickets, you bear the risk.

General rule: For connections at busy airports (YYZ, YVR, YUL), give yourself at least 90 minutes. If you need to clear customs and border services (arriving from outside Canada), allow 2+ hours.

International vs. Domestic Connections

When you arrive in Canada from an international destination, you clear customs at your first point of entry — even if you have a domestic connecting flight. You collect your checked luggage, clear CBSA, re-check your bags, and proceed to your domestic gate.

For example: flying London → Toronto → Halifax. At Toronto, you clear customs, collect bags, re-check them, then go to the domestic terminal. This takes time. Do not book a 60-minute connection for this type of itinerary.

Same Booking vs. Two Separate Tickets

One of the most important things to understand about your itinerary: are all your flights on one booking reference, or are they separate?

One booking: If a delay causes a missed connection, the airline is responsible. They rebook you, cover accommodation if needed, and you are protected under APPR.

Separate bookings: If a delay on a ticket you booked with Airline A causes you to miss a flight booked separately with Airline B, each airline is responsible only for its own flight. You have no automatic recourse for the missed second flight.

Reading the Fare Class

Buried in most itineraries is a one-letter fare class code. Common examples:

• Y = Full-price economy
• K, L, Q, T, V = Discounted economy (different levels)
• B = Basic economy (on some carriers)
• J, C, D = Business class
• F = First class

These codes affect miles earning rates on loyalty programs. A cheap economy ticket in fare class V earns fewer miles than a full-price Y ticket, even if you sit in the same seat.

The Operated By Note

Always read the “Operated by” field. If your Air Canada ticket is operated by Jazz Aviation (Air Canada Express), you are flying a smaller regional aircraft — which may have different carry-on size limits and different in-flight services.

Understanding your itinerary helps you travel smarter. Browse flights on FareSeeker →