Immigration? Customs? Flying from Seattle to Heathrow to Oslo

Is your LHR to Oslo on BA and on a single booking?

If not, your chances of making the 2nd flight are as viable as the proverbial snowball in ____

Unless there has been a change at LHR, since I was there several years ago, you will have to go through a full security screening process between flights. ( been through too many airports since to recall what the passport control process was)

If its a connecting BA flight and you have biz class tix ( for expedited lines) you can probably make it.

The only time I have encountered an airline holding a plane is when there were significant numbers of passengers coming from another flight and the departing flight was the last of the day to that destination. Your companion may be overly optimistic about the plane being held for you.

The Heathrow airport website has a connections tool to help you through the process. Plug in the date and flights and it will list the process.

http://www.heathrow.com/flight-connections

Your travel companions will some day get left behind too. If you are on a BA itinerary to Oslo, your bags should be checked directly through to that destination and you should be able to stay in a secure area without going through the process to enter the UK. If not, you are in trouble. You may not make it in 60 minutes even if the bags are not a concern. Security procedures have increased there and all across Europe, slowing everything down. You do not have until the stated time of departure to get to your seat. Airlines want passenger inside the plane, not just at the departure gate, well before take-off, and might even begin removing your checked luggage from the plane so it can leave on time. Keeping planes on schedule is a crucial factor in the business, more important than one or two stray passengers.
Perhaps your originating airline, the one that issued the ticket, can give you more definitive information. You can also look at the Heathrow website to see which terminal or terminals will be involved for your particular flights.

"my travel companion says they will hold the plane if we're not at the gate on time".

Please let us know how this works for you!,,

"my travel companion says they will hold the plane if we're not at the gate on time".

Please let us know how this works for you!,,

Please post again with the name of the airline from LHR to Oslo. Did they give you a terminal number in LHR?

Keep in mind T5 has two additional "wings" where if your flight to the UK docks at one of them you will need to walk to the underground rail to the main terminal building. You may have a few minutes wait until the next one arrives. Then you go through a longish walk toward immigration, which you will bypass as you follow the signs for onward flights, where you get a chance to discard things and pick up plastic bags, you turn a corner and walk further down a corridor where you will see a line forming for scan and screening that you will go through before you can proceed to the next gate. We had ample time- 2 hours. Our BA flight on the return was a bit late leaving Rome and by the time we got through the screening the flight home was boarding. but taking a long time to do it. One hour is dicey at best.

"My travel companions said they will hold the plane if we're not at the gate on time"

I spewed coffee all over the place when I read that!

Sorry, but if it is just the two of you who are running late, there is slim to no chance of them holding the plane for you even if you are a top tier frequent flyer on that airline. I fly a lot (reached 1 Million miles on one airline last year! That airline has never held a flight for me.) but airlines don't care. Do you really think they will inconvenience an entire plane load of passengers for a couple of late ones? In all my years of flying, only one airline, Air Canada, held a flight I was on. And, even though it benefitted me, it was the fact that 40 passengers on that flight were on a late arriving connection including me that caused them to hold it. It would have cost the airline more to let the plane go without us that to hold the flight.

An hour is bang on the minimum for a T5-T5 connection so it could have been sold as a single ticket (not to say that it was bought as such), even though there isn't really any margin.

This BA document gives you the info - note you have to be at the gate 20 mins before departure.

You have to clear security - and enter it 35 minutes before your departure time. If you arrive at B or C, and your flight departs from B or C you can use the satellite security. Otherwise you have to use one of the main security points in A along with originating passengers.

If I divert onto a story for a moment, I can remember BA holding a plane for me once, nearly 30 years ago. This was because of late arrival because of tube failure and I called through from the check-in desk. I chuckle remembering it as I got to the gate followed by a dozen other people. The gate staff told me that they had only held it because of the call on my behalf - so if I hadn't been on that flight the other 12 would have missed it. It was a different age then for air travel though.

Just follow the directions given in the "flight connections" like given above.

If it is on one ticket, meaning you booked Seattle to Oslo and you are stopping over just to change planes, don't get too worried. Even if you miss your connection, they will put you on the next flight.

They will not hold the plane for two people unless it's just a couple of minutes.

A mere hour to make that connection would make me so nervous. My last two BA flights out of Seattle to LHR (September 2015 and April 2016) departed between one and three hours after their scheduled departure times, both times because the plane was late getting in from London. The pilots always seem to make up some time in the air, but it's been a few years since I've arrived in London on time. Obviously, this doesn't happen all the time and maybe I've just been unlucky recently (and should probably make an offering to the airline gods), but I would really think twice about that narrow of a connection time.

looking at Heathrow schedules they are both BA flights with transfers within T5. The official minimum transfer time is 60 minutes. They can probably get on you on board with half that - but your checked bags will follow 4 hours later!

60-minutes between flights at LHR is the very bare minimum of margin between flights. Pray the flight either arrives early or, there's enough passengers that are delayed at security check that they'll delay pulling-back. Terminal-5 is actually 3 separate buildings with a subway connecting them all; gate-A handles the smaller planes and security while, gates B and C handles the wide-body internationals. Because you're arriving from outside the EU zone, then traveling within, you'll go through a round of security upon landing at LHR. Everyone goes through, same deal as the US, get your ID, ticket and fluids ready. They're pretty efficient and they move you through, just pay attention.

Short story:
I was transferring between a flight from Milan to SFO, upon deplaning at LHR there was a BA agent to meet me at the gate, she escorted me the entire way to my connection. Up and down the escalators, on/off the subway and over to my gate, I was only traveling coach but, it was a very nice bit of service.

It will be tough as several of the BA flights from the US park at Terminal 3. It is likely that your Oslo flight will leave from Terminal 5 so you will have to make that journey. I am hoping that you have a T5 to T5 transfer as that will help tremendously. We have flown the Denver/LHR BA route and each time that flight has parked at T3. We went on to Milan and had to go out of T5. The transfer to T5 was kind of cool as you bus through different parts of the airport. But it takes some time.

Just got back from my trip. We landed at Heathrow, and successfully caught the flight to Oslo.

Glad to hear you made it. It’s always nice to hear how these things work out. Hope the rest of your trip went well too.