Heathrow LHR connection time for separate ticket

These aren’t connecting flights.

Normally you should be there for check-in for your Lisbon-bound flight two hours ahead of time.

I don’t know Heathrow that well but I wouldn’t try doing this with my own money.

are you familiar with the official connection planner (they make no guarantees)? https://www.heathrow.com/flight-connections

There’s a lot of questions here and this seems like a stressful itinerary. I assume you have a Canadian passport. Is your flight from Vancouver to Seattle truly a layover or are you connecting to the LHR flight in Seattle? If the LHR flight originates at SEA then you will also have to enter the United States, I hope there’s enough time for that.

If the LHR flight originates at SEA then you will also have to enter the United States, I hope there’s enough time for that.

I think the OP probably knows this already, but they would have to clear US passport control and customs no matter what — there is no sterile transit in the US, so any time you land at a US airport from an international flight, you always have to go through US border formalities, even if you are connecting straight on to another international flight.

In this particular case because the OP is starting from Vancouver they’ll do US border formalities in Vancouver.

You can transfer airside but be aware you will need to clear security in T3. Check in for the Lisbon flight online if at all possible.

To catch your separate flight to Lisbon, you’re not allowing yourself enough time; you are not allowing for anything to go wrong; your itinerary is based on perfection. You are rolling the dice.

On my flight to Heathrow this past Friday, we spent over 2 1/4 hours waiting to taxi at JFK because of a wind storm; 3 of the 4 runways were closed. The only open runway was for both takeoffs and landings. Under your scenario, I would have only had 15 minutes to catch that Lisbon plane not even 30 minutes because the flight could close 15 minutes before departure. If your TAP flight is roundtrip between Heathrow & Lisbon, your return flight to Heathrow would automatically be canceled if you miss the outbound flight to Lisbon.

To answer the question asked, yes you can use the Flight Connections path with separate tickets IF you have carry-on luggage only, have checked in for the onward flight, and have your boarding pass in hand. Marco answered this as well, and I have seen this confirmed on another forum dedicated to air travel. Someone actually emailed Heathrow and got an answer!

Assuming your flight from Seattle is on time, and arrives at the gate without delay, you should be OK, but it is indeed a tight connection. I prefer four hours when making a “separate ticket” connection at Heathrow. But hopefully all will go smoothly for you.

I’ve done this where we had checked baggage (so we couldn’t use flight connect) and made it with time to spare, but I won’t ever do that again. My concern is that you’re doing this in December where PNW weather can be iffy. We did it in June.

If there is no chance of changing, knowledge will be your friend. How much will it cost you if you miss your flight on TAP? How many flights are there to Portugal each day? Can you book a seat close to the front so you can exit quickly? Look at the Heathrow website for pictures as to what you will be seeing as you make your flight connection. Look at the airport map for the gates that TAP uses as well the terminal.

You are gambling with separate tickets; it seems that most who have done this have won more times than losing; you just always need to know plan be win you lose. Do you?

Since you have already bought the tickets mentioned you will have to hope that your flight to LHR arrives on time or early.

This may help answer your questions regarding Termial 3 to 2 connections:
https://www.heathrow.com/flight-connections

Heathrow Flight Connections guide

Essential information if you're transferring between flights at London
Heathrow – get a step-by-step guide to your Flight Connection.

You didn't say if your TAP ticket is a round trip to Lisbon and back to London, or a one-way to Lisbon. If you miss the outbound of a round trip ticket, the return will be canceled.

Assuming on-time arrival/departure:
https://www.heathrow.com/flight-connections/personal-connection-planner/DL4349/TP1359/13-DEC-2019/13-DEC-2019/2/6A

Time needed for this connection: 75 minutes. You have 2hr 30min available. Our step-by-step guide shows you how to make your Flight Connection.

1. Welcome to Heathrow! - On leaving the aircraft, please follow the purple signs for Flight Connections.
   

https://www.heathrow.com/airport-guide/getting-around-heathrow/airport-maps

1. Flight Connections bus - A dedicated bus will transfer you between terminals. Buses are free and depart every six to ten minutes.

2. Hand baggage check - At this point your hand baggage will be checked to ensure it conforms to UK and EU regulations. Please be aware that liquids in containers over 100ml are not allowed through security.

3. Security screening - 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.

4. Airline desks

5. Departure lounge

Note:
https://www.heathrow.com/airport-guide/getting-around-heathrow/travel-between-terminals

Terminal 3 to Terminal 2

You can walk between Terminals 2 and 3 via the pedestrian underpass.
The route is well signposted and can be followed on our interactive
Heathrow map.

Average journey time: 10 minutes

I've done this 3-4 times in the last 10 yrs with no issues. Separate tickets. No checked bags. I usually give myself about 3 hrs in between flights. Our flights have always arrived on time or a bit early, and I've gone from terminal 2 (where Air Canada lands) to term 3 - usually for a flight with BA to other points in Europe - I've never had it take more than 25-30 min to change terms following the secure flight connections. The bus comes along every 10 min or so and about 10 min to term 3. Never had it take very long to get thru security.

Now, we are usually landing before 9am, so security lines have been very light (usually thru in less than 10 min), but we've always had time to grab breakfast and still have to wait for our gate assignment.

Just because it's worked for me doesn't mean it will work for you, but I've always been comfortable with a 3 hr layover.

I believe the pedestrian walkway between Terminals 2 and 3 is landside, not airside, so you would need to go through immigration to access that. Better to follow the Flight Connections path and stay airside.