Changing planes but not a connecting flight

I dont know what the significance, if any, of "connecting flight" is. It seems to me that when you check in for your first flight you will have your luggage checked through to your final destination (whether it is on the same group of airlines or not). You do not intend entering UK. Your luggage would be sent on to your next flight, you stay within the "in transit" area of the airport. So time would not be excessive If you go out through immigration and customs, they suggest a minimum three hours check-in... added to your time getting through immigration and customs to enter UK, which "could' exceed one and a half hours

Thank you for your reply. But I am purchasing the two flight separately. I believe in a connecting flight, I would only have to check in once for the flight and my bags would continue on. But with a flight to London and then a separately purchased ticket to Norway, I do not believe my luggage will continue on. I believe that I will need to basically enter London, get off the plane, get my luggage as if I am staying in London, then return to the ticket desk to check in for my next flight and basically start all over. If you have any other advice, I would appreciate it greatly

Melody, you have the correct sequence. What would be helpful, however, is which airport and which airlines?

Flying royal dutch, partnered with Delta into Heathrow and then propably SAS into Tromso, Norway

Delta and KLM use T1. SAS uses T3. It's going to take you about an hour to get your stuff and pass through the bureaucracy. You've got to be checked in an hour prior. There's no time to make the transfer, even if you make the first gate time. Three hours should be okay.

I will add that even Eds estimate is optimistic. I was at heathrow a couple weeks ago, it took most of an hour and a half to get through Immigration with no checked luggage, then time to figure out the inter terminal trains plus wait time for the train. Keep in mind you will then need to re-check your bag on the SAS flight, then go back through security and get to your gate. The other issue is that if you miss your flight, SAS has no obligation to put you on another flight and will likely charge you a hefty ticket change fee plus any difference in fare cost. As a result, I would leave as much time as possible between flights.

In that situation, with a non-EU passport, I'd want four hours. There's no guarantee your flight will arrive on time. Actually, I might plan to check into the Yotel for a shower and a nap, and fly out in the afternoon, but I'm retired so I'm not time-limited.

Thanks y'all. The later flights put me into Tromso after midnight, but it's still better than missing the flight.

Melody - We have been doing the same type of connections through Heathrow for the past 5 or so years. We usually plan to leave at least 4 hours, often 5 to make our next flight. Although we have booked our tickets separately, most of the time we have been able to check our bag when needed through to another airline on another ticket. The only carrier that wouldn't let us do that so far is Virgin Atlantic. They wouldn't let us check a bag through from to a British Airways flight. One tip is to print your SAS boarding pass before you leave on your first flight. Having the boarding pass in advance has saved us a few times with late flights, including that transfer from Virgin Atlantic to British Airways during that whole liquids mess in 2006 when everyone had to check every bag.

Thanks for the advice, particularly about printing the boarding pass. So you ask when checking in for the first flight from the US if they can send my bags on to Tromso via SAS?

If you do not check bags, you do not have to go through immigration to transfer from T1 to T3. You can stay "airside" and use the dedicated bus. The Heathrow website has instructions for these transfers between terminals. It says from T1 to T3 the minimum connect time is 75 minutes. That is probably for a " connecting" flight booked on the same ticket, with carry on or checked through luggage, and a pre-printed boarding pass for the second flight. We did a similar transfer on separate tickets in May. I timed the transfer and from the time we got off the plane at T5 to the time we were in the waiting area at T3 was 45 minutes. Of course I would not count on that and suggest adding an hour or so for safety. If you check a bag and have to pick it up, you have a whole different game. Going through immigration can take a long time--- we were in line for an hour on our return flight when we spent a night in the UK. Customs is a non-event but the immigration lines can be very trying for non-Eu people. I would agree with the advice to allow 3 hours or more if you have to do this.