We are flying from Seattle to Heathrow on Delta and arrive at 3:05 pm (terminal 3). We have a separate ticket booked on British Airways to Edinburgh that departs at 5:25 pm (terminal 5). Will it be possible to go through customs and security and make this flight? If we switch to the 6:30 pm flight will we then have enough time, or do we need to change to the 8 pm? We are not planning to check bags.

  • 1
    If your flight from Seattle to Heathrow is delayed, will you be able to rebook your flight after having missed it? Usually, that's not possible. For flights on separate tickets it's generally better to leave several hours.
    – phoog
    Jul 3, 2016 at 21:07
  • Two minor nits - it's British Airways you'll be flying with, and second it's immigration you might get delayed at rather than customs. For an International to Domestic connection at Heathrow, customs is a small red phone tucked away on one wall!
    – Gagravarr
    Jul 4, 2016 at 10:30
  • @Gagravarr you don't clear customs at Heathrow, you clear it at the last customs port on your journey; customs at Edinburgh for domestic arrivals is a telephone there in the baggage hall used for non-EU origin passengers (though easily missed travelling without luggage!)
    – gsnedders
    Jul 4, 2016 at 19:20
  • @gsnedders You clear customs twice - you & hand baggage in Heathrow, and your checked luggage in Edinburgh. You have to seek out customs in Heathrow if you need to declare things - there's a red phone just after domestic immigration. See section 7 of the Heathrow Intl-Domestic connection guide You will pass through security screening at this point. If you are a non-UK resident and have goods to declare to HM Customs, please use the Customs telephone before security control.
    – Gagravarr
    Jul 4, 2016 at 19:46

2 Answers 2


It's certainly possible that you could make the flight. You will arrive at terminal 3, follow flight connections and take the bus to terminal 5. Providing you arrive on time this would not be a problem for a 2:20 connection. If you arrive late and miss your connection, you will have to purchase a new ticket. I would recommend you view the history of DL36 SEA-LHR on flightstats to decide if you wish to take that risk.

If you do miss it, there's a good chance you could purchase a new flight with Avios even after arrival, providing you have some Avios from previous crediting to BA, or if you choose to purchase some. An Avios ticket from LHR to EDI would be 4500 avios and £17.50 each way.

Taking a quick look on flightstats, shows it arrived 82 minutes late two days ago. However it generally has a fairly good on-time performance.

Edit: Heathrow suggests the connection typically requires 90 minutes from landing.

BA recently introduced some new ticket types. Previously only expensive flexible and semi-flexible tickets were changeable, but now there are Basic, Plus and Plus Flex tickets. On domestic flights there is business UK. Business UK, Plus and Plus flex tickets allow change of flight on same day if seats in cabin are available. Details here.

As an example for a random date I pulled up:

The difference in price (each way) between basic and plus can be quite minimal. If you chose the latest flight on the day, which is the cheapest, and you chose the Plus fare, you could change it to any earlier flight after you arrive.

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Details of plus fare:

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  • Thanks, Berwyn. If we re-book for the 20:00 flight to EDI to allow for max transfer time, but we end up in T5 with plenty of time to spare, do you know if BA will allow departure on an earlier flight via standby if seats are open, as is common here? Thanks again.
    – Jennifer
    Jul 3, 2016 at 21:24
  • 1
    @Jennifer No, BA will not allow standby on early flight normally. However, they now have a certain ticket type that does allow flight change on same day. I'll update my answer with a link
    – Berwyn
    Jul 3, 2016 at 21:26
  • Flight connections only applies if luggage is checked through, given they're on separate tickets. A quick look on Google suggests Delta won't check luggage through when it's on multiple tickets, even if it's within Skyteam (which BA isn't).
    – gsnedders
    Jul 4, 2016 at 19:17
  • 1
    @gsnedders OP says they're not checking bags
    – Berwyn
    Jul 4, 2016 at 19:18
  • @Berwyn bah, I failed to read! :)
    – gsnedders
    Jul 4, 2016 at 19:18

If your incoming flight is on time, it is certainly possible to be at the departure gate for EDI by 4:05. Just follow the signs for Connecting Flights and specifically UK Connections.

However, if you are delayed, BA has no real obligation to honor the outbound ticket. They might, depending on circumstances. BA will only protect you, meaning re accommodate at no charge, if you arrive on a delayed BA or other OneWorld flight, even if it's technically a separate ticket. (Note, I know this is an AA rule, presumable BA has the same.)

If not worrying is important to you, take the 2000 flight. T5 departures is not the worst place to wait.

  • BA does not follow this rule about protecting unconnected tickets from oneworld. If you want to be protected you need to be on one ticket. At LHR flying to EDI you would probably be accommodated if coming off an AA flight but I wouldn't count on it. From DL, not much chance.
    – Calchas
    Jul 4, 2016 at 22:49

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