Interlining: Can you check bags through on separate tickets?

When travelling on separate tickets, the ability to get all your boarding passes upfront and check your bags through to the final destination can mean the difference between a seamless connection and a stressful rush- or even denied boarding!

This is known as an interline agreement, and is one of the most basic kind of partnerships between airlines (below a codeshare, alliance or joint venture).

In this post we’ll look at what interlining is, with a particular focus on Singapore Airlines.

What is interlining?

While there’s probably a more technically correct definition, you can think of interlining simply as an agreement that allows Airline A to send passengers onto Airline B, without requiring them to reclaim their luggage or check-in again.

Interlining arrangements allow for the sale of a single ticket comprising of multiple airlines, as illustrated in the example below from SIN to ZRH to NCE, with the first leg on Singapore Airlines and the second leg on SWISS.

However, interlining arrangements also create the possibility of a passenger enjoying the same convenience, even when travelling on separate tickets. 

Of course, in an ideal world you’d simply book everything on a single ticket, but that’s not always possible:

• You might book awards across two different programmes
• It might be cheaper to book two separate tickets than one combined ticket

And in these situations, the presence of an interline arrangement can either be a matter of convenience, or absolute necessity. 

Convenience

Suppose I want to fly from SIN to MXP, but can only find Business Class award space on Qatar Airways from KUL to DOH to MXP. In that case, I might buy or redeem a separate Singapore Airlines ticket to reposition to KUL.

Since Singapore Airlines and Qatar Airways interline, I can get my boarding passes for the entire journey in SIN and check my bag all the way through to MXP, eliminating the need to clear immigration in KUL, claim my bag, check in, and clear departure immigration again.

Necessity

If you have two separate tickets from A > B and B > C, but cannot enter country B without a visa (and don’t intend to apply for one), then you must be able to check your bag all the way through from A > B > C, since you can’t enter country B to retrieve and re-check it.

This isn’t so big an issue for Singaporeans, because our passport provides visa-free access to so many countries (though if you were flying on separate tickets through say, India, then you would need an Indian visa to enter the country if your bag can’t be checked all the way).

However, it could very well be a problem for other nationalities. You should note that some airlines will err on the side of caution and refuse check-in if you don’t have the right documentation to enter the “transit” country (since they’re on the hook for the costs of repatriating you should anything go wrong), so buying separate tickets in this case is a much riskier matter.

Will Singapore Airlines interline on separate tickets?

Singapore Airlines’ official policy on interlining and through checking baggage on separate tickets is as follows.

In short, Singapore Airlines will check through bags on separate tickets, provided the following three conditions are met:

1. SIA has an interline agreement with the other airline
2. the minimum connection time is met
3. the connecting point accepts through-checked bags

Do note that this refers to a situation where Singapore Airlines is the first airline you’re flying; other airlines may have different policies and may not check your bag through, notwithstanding the fact the above three points are met.

SIA’s interline agreements

At the time of writing, Singapore Airlines has interline agreements with more than 100 carriers worldwide. The information below is extracted from the KVS Tool (which requires a paid subscription to access).

[KVS Tool 11.5.3 – Reference: Interline Agreements [IET]: SQ]

You can look up airline codes via the IATA website, but for convenience, I’ll list them in a drop down box below (do note that some of these airlines are no longer in operation, but remain in the system nonetheless).

Note that the list is not limited merely to Star Alliance carriers; SQ has interline agreements even with oneworld, SkyTeam and unaligned airlines. Interline agreements also exist with budget carriers such as Vueling and Wizz Air.

Minimum Connection Time (MCT) is met

If you want to check your bag across two separate tickets, you must make sure the Minimum Connecting Time (MCT) is satisfied (it should go without saying that an itinerary sold on a single ticket will always respect the MCT).

As the name suggests, MCT is the minimum time between the scheduled arrival of one flight and the scheduled departure of another. Bangkok, for example, has a MCT of 1 hour 15 minutes for all connections, whether domestic to domestic, domestic to international, or vice versa.

This means that if you book a separate SIN-BKK and BKK-KIX ticket and the arrival of the first flight is within 1h 15 mins from the departure time of the second flight, your request to check your bag through will be denied.

I personally use the KVS Tool to look up MCTs, but if you don’t want to pay for a subscription then your only option is to Google [airport name] minimum connection time and hope that something turns up.

Connecting point accepts through-checked bags

Interlining may not be possible in certain situations, like when you’re travelling between two different airports in the same city.

For example, if I buy a SIN-HND ticket with Singapore Airlines, and NRT-JFK ticket with ANA, I cannot check my bag all the way through, despite the fact Singapore Airlines can interline to ANA.

Likewise, US airports do not have international transit zones as such, and all passengers arriving on international flights must clear customs and immigration, even if they don’t intend to stay in the USA. 

For example, if I buy a SIN-SFO ticket with Singapore Airlines, and a SFO-YVR ticket with Air Canada, I will not be able to check my bag all the way through to YVR.

Other important things to know

Interlining on separate tickets is not a given!

Interlining agreements are primarily concerned with facilitating the travel of passengers across different airlines on the same ticket. Just because two airlines have an interline agreement does not mean they’re obligated to check you through when travelling on separate tickets.

However, some airlines offer this service as a courtesy. Singapore Airlines is one example, and so is Cathay Pacific:

As a courtesy, Cathay Pacific will through-check you and your bags to your final destination if you are travelling on separate tickets involving connections with our interline partners. However through-check may not be possible on your return journey if your travel begins with an airline that does not provide separate ticket through-check service.

-Cathay Pacific

Still, you may encounter the odd agent who is unfamiliar with the rules or unwilling to assist. In fact, some airlines have an explicit policy of not checking bags on separate tickets, like Alaska Airlines, American Airlines, British Airways, EVA Air and STARLUX, so you shouldn’t take it for granted that you’ll be able to do this.

Long story short: there is always some degree of risk involved when travelling on separate tickets with a check-in bag.

Regular customs rules still apply

Interline agreements are still subject to the standard customs restrictions.

For example, Singapore Airlines and JetBlue have an interline agreement, but US laws require passengers to collect their bags and clear customs at their first port of entry. So if you had a Singapore Airlines SIN-SFO and a JetBlue SFO-BOS ticket, you would still need to collect your bag in SFO and clear customs before sending it off again on the SFO-BOS leg. 

Similar rules apply to Australia and New Zealand, where your connecting flight is a domestic one. 

This doesn’t let you avoid baggage fees

If you have two separate tickets, one with free baggage and another without, does interlining let you avoid baggage fees altogether?

You wish! Obviously, things don’t work that way- it’d be one mighty fine loophole if so. In this scenario, even if an interline agreement exists, you’ll need to have paid for baggage with the second carrier for the first carrier to check through your bag.

A variation of this question is what happens if you’re travelling on two separate tickets, and the allowance of the first carrier is higher than the second (perhaps you have elite status with the first carrier, but not the second). It’s hard to say for sure, but FlyerTalk suggests that in the case of Singapore Airlines, they will honor the allowance you have with them. 

Conclusion

When travelling on two (or more) separate tickets, the ability to check your bag all the way to the final destination depends on whether an interline agreement exists. 

Keep in mind though- that’s a necessary but not sufficient condition. Some airlines have a policy of not checking bags through on separate tickets, others may not accept you if you lack the required documentation for the transit point, even if you can show them proof of onward travel.

So there’s always some degree of risk involved with travelling on separate tickets, and it’s a good idea to have a backup plan should the worst happen.