I'm flying from Taipei (TPE) - San Francisco (SFO) - Toronto (YYZ).

I have a two-hour layover in San Francisco. This trip was booked as one ticket with one airline. However, the second leg of the trip looks like it will be a codeshare with a partner airline.

From some research, it seems like I will have to pick up my luggage in San Francisco, go through US customs, and drop the luggage off again. If this is the case, will I have enough time on the layover or is it likely that I'll miss the second flight? If it's not enough time, what's my best course of action?

  • What day and time of day? Will you have to go through security again (might depend on terminal(s)) Those are factors.
    – steve v
    Oct 13, 2023 at 21:12
  • It will be early morning, landing at 6:45am and leaving at 8:40am. I am unsure if I will have to go through security again.
    – LCee
    Oct 13, 2023 at 21:28
  • Just to clarify a common error: customs deal with goods, and is the step just after baggage reclaim most people just walk through. The part which takes time (other than security) is passport control / immigration.
    – jcaron
    Oct 17, 2023 at 9:20

3 Answers 3


Like other US airports, SFO doesn't have a sterile transit area but it does have a kind of organised international-to-international transit procedure. There are many flights from Europe to Polynesia using this route. In this case, there is staff to guide you and passengers doing that get a kind of bright orange plastic transfer “tag” (for lack of a better name, it looks like a giant solid plastic bookmark).

I don't know if your flight will follow the same procedure but since you are not trying to “self-transfer” and got a single ticket covering both legs, the airline thinks its reasonable. I assume that you are also unlikely to be the only passenger doing this and that the airline will assist you if the wait at immigration is abnormally long.

In practice, you will have to proceed to the US immigration check where the wait can indeed be significant and, in your situation, stressful. After that your bags should already be there (if you need to collect them) and you can immediately proceed to the security inspection and the gate. The wait at this security checkpoint always seems quite short and you don't need to budget a ton of time for the other steps. Follow the “transfer” signs and do not exit to the regular departure area or go through the regular check-in procedure there. The international terminal also doesn't feel that large (compared to large hubs in Asia or Europe I know, even if Wikipedia tells me it's the largest international terminal in North America).

PS: This is based on my observations during multiple recent trips to SFO but I have actually never used the exact route you mention.

  • 2
    I believe the minimum connection times are regulated per-airport - which means that it’s not just the airline thinking this connection time is ok in general. Nonetheless, sometimes those MCTs are kind of unreasonable.
    – steve v
    Oct 14, 2023 at 1:26
  • 1
    MCT times are set by the airline. There will be a default time set by the airport if the airline has not published their own time.
    – Doc
    Oct 15, 2023 at 16:01

From some research, it seems like I will have to pick up my luggage in San Francisco, go through US customs, and drop the luggage off again.


If this is the case, will I have enough time on the layover or is it likely that I'll miss the second flight?

If things are "normal", you'll be fine. But there are many different variables (delays, late or lost bags, immigration, customs, getting lost between terminals, security, etc) so no one can say with a 100% certainty. I'd say it's 90%+

If it's not enough time, what's my best course of action?

The airline will rebook you to the next available flight. If would be good to research up front what that might be. If this is a Star Alliance ticket, they can rebook you on both United and Air Canada and there are plenty of daily flights. However if you are coming in late in the day, you may have to stay the night: in this case you are typically entitled to a hotel and food but that depends a bit on your negotiation skills, so it's good to prepare a bit.

  • 2
    The OP notes in the comments that they're arriving in SFO at 6:45 AM. Something would have to go badly, badly wrong for them to be forced to stay in SFO overnight, given that the last SFO-YYZ flight of the day is a United redeye leaving at 11 PM. Oct 16, 2023 at 21:47

You will have to go through security again and the wait times for passport control and security can vary a lot.

You can view average wait times for two of the variables that will affect your total connection time.

  1. For passport control: Average wait time reported by US CPB. It varies quite a bit by time of day and citizenship status. For an overall average you could look here, where ~20 minutes is reported as the average, and SFO ranked the 4th slowest.
  2. You will go through a TSA checkpoint again. Your average TSA wait time can be estimated here or here. At the moment the former shows ~10-15 minutes and latter shows ~12 minutes

Your connection time will include:

  1. Waiting to deplane
  2. Immigration (passport control)
  3. Getting your bag and walk through customs
  4. Drop your bags again
  5. Going through security
  6. Travel time between all of these things

Let's put some hypothetical numbers in place. Edited based on comments

  1. Waiting to deplane once you arrive at the gate - 15 minutes
  2. Immigration - 20 minutes (average reported above)
  3. Getting your bags - (just travel time to collect if you are lucky), no extra time for customs if you have nothing to declare and are not selected for a random search
  4. Dropping bags again (just travel time if an agent is available and you don’t have to go back to ticketing)
  5. Going through security - 10 minutes (lower part of average reported above)
  6. Travel time between all of these things - 20 minutes

No major slowdowns, and relatively quick pace for bags, customs, and security. That would be 1 hour 5 minutes, leaving plenty of time before your departure.

If any one of these steps is delayed (passport control being being a big variable), your chances of making the connection become worse.

  • 1
    Like all US airports, SFO does not do sterile transit for incoming international flights, so you will need to queue for US immigration (can be 1+ hr) and go through TSA security to catch your connecting flight. There is a bag drop for connecting flights after Customs though, so you don't need to check in again. Oct 13, 2023 at 23:12
  • 1
    I don't thin the TSA wait times apply. The security checkpoints you have to go through when your journey starts at SFO are always considerably busier than those located immediately after immigration / luggage collection area. Same for check-in if it is even necessary.
    – Relaxed
    Oct 14, 2023 at 0:44
  • The average times reported don’t seem to differentiate based on where the checkpoint is so I have no better number than 10 minutes. I updated the hypothetical “no extra delay” scenario based on the baggage info you reported. Even at 10 minutes the main potential for missing the flight would be above average wait times for customs. That number is highly variable if you look at their reports but seems to be lower at the early hour of this flight.
    – steve v
    Oct 14, 2023 at 0:48
  • 1
    "Without knowing whether you'll need to go through security again" If you have to go through immigration when arriving in the US, you always have to go through security again if you need to take another flight. It's just that some airports have a separate security checkpoint for people connecting from international arrivals.
    – user102008
    Oct 14, 2023 at 1:00
  • The SFO site says that they exit to the public area and have to go back through the standard checkpoint. But another user indicates otherwise.
    – steve v
    Oct 14, 2023 at 1:12

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