Time needed at LHR

If you missed the 245, KLM does not have to do anything because that was there your fault not theirs.

You need to allow more time. My rule is four hours and willingness to pay the price. In other words, if you’re even later than you expect, and you don’t arrive in time for the 4 o’clock fine you need to be willing to pay whatever it cost to get to Amsterdam. If not, you need more time. I’m always aware that this could actually cost me money because I may have to buy a ticket at the last minute or a train at the last minute.

Your other risk or is, it is very early, there will probably be some schedule changes on both airlines between now and your flight. That’s the other reason you want a big pad of time

I don’t believe you have to go through immigration, but I do believe you have to go through security again.

At Heathrow, since you are buying a completely separate ticket to go on to Amsterdam, they have no way of knowing that London is not your final destination. That makes me think very much that you will have to go through UK immigration before you can go find the place to check in for your Amsterdam-bound flight, and go through security and emigration.

The reason you are "saving" money is because this is a very bad idea. When you have to buy a new ticket on the spot, it won't seem so cheap.

This is pretty much a bad idea unless the amount of money you are saving is amazing.
If you check bags, you will go through both passport control and security at LHR. If you do carryon only, you can use the flight connections path and only have to go through security again. This assumes you have been able to check in for KLM flight online.

I would not choose the 2:45pm flight under these conditions and I really hope you don't get burned on the 4:05 flight. KLM has no responsibility to put you on another flight, you would be considered a "no show."

The flights from Seattle to London and London to Seattle on British Airways are "turn around flights." That means the plane flies from one to another and then turns around and flies back again. There is always the possibility of flight delays that develop over the course of several days or flights. I recently experienced this when the flight was 3 hours late arriving and therefore had to be 3 hours late departing. They try to catch up the time, but are not always successful.

If I were continuing on a completely different ticket, I would probably build in an overnight at LHR. That costs time and money and you have to ask yourself if you are really saving money with the two ticket plan.

That exact flight (BA 48), departing in the evening, is our standard flight to Europe, and we have taken it at least 10 times. I would never do an unprotected connection with that flight with less than 4 hours between flights. And that is with a BA to BA flight, all within Terminal 5. To get to your KLM flight, you will have to change terminals, because T5 where BA 48 comes in is all British Airways. With a separate ticket on a different airline, you will not be able to use the airside transfer for flight connections, so you will have to go through immigration and transfer landside, using the Heathrow Express or other connector.

While that flight is usually on time in departing SeaTac (within, say 30 minutes of schedule), it is often late in landing because it has to circle to wait for a landing slot. And one time we arrived at the gate on time but the jetway connector did not function, so we had to wait 45 minutes for them to bring up a portable stairway so we could deplane. It took that long because the first one they brought did not work.

Schedule changes are usually less of a concern with BA, in our experience, but in the last few days we have gotten notice of very minor adjustments (10 minutes or less) in 3 of our 4 September flights with BA.

Bottom line is there is no way I would choose the 2:45 flight, and I would not be comfortable with the 4:05 one either. I “might”:take the risk if it were super-cheap, and I knew there would be a later flight possible if I missed that one, AND I had some assurance that the last-minute price for that one would not be outrageous. But I don’t know how you figure that out now for a flight in September.

Lola raises an excellent point about the terminal change required for going from BA to KLM. I do believe that there is a flight connection option that would not require you to go through passport control if
1) no checked luggage
2) you have your boarding pass for KLM already

This link describes the bus that goes between terminals for flight connections. This does take time. Anything at LHR takes time and usually involves a lot of walking.....

https://www.britishairways.com/en-us/information/airport-information/flight-connections

One other thought. You may already have your ticket on BA and already be committed to this strategy. If so, no need to keep reading this post. Otherwise, consider Seattle to Amsterdam on Iceland Air. I don't think it is more expensive than your current strategy and gives you a protected connection in Iceland where it is pretty easy to make the connection.

Just a possibility. I wish you the best of luck.

You may be saving money, but definitely adding stress. There’s no way I would do the 2:45. Even the 4:05 is cutting it close. You will need to go through immigration, collect any checked bags, go through customs, potentially change terminals, wait in line to check the bags with KLM, go back through security, and get to your gate. Even if you are not checking bags, you still go through immigration security. Transfers between terminals can be very long.

KLM has zero obligation to you if you miss your flight regardless of the time of the flight. If you miss the flight, you have to buy a new ticket, pay for food & hotel if the new flight is the next day, etc.

The last time I went through LHR:
Plane to bus
Bus to terminal
Security: All passengers had to put their liquids into new plastic bags
To next terminal
To Bus
To plane

Used every second of 3 hours.

I just checked the Heathrow “flight connections” and Carol is correct that you can do the transfer from T5 to T3 airside IF you you have your boarding passes for the KLM flight. The minimum connect time is 90 minutes, and you do have to go through security again at T3. But I hope that by now you are convinced that this is risky on separate tickets, even with the 4:05 flight.

So I am wondering why you are proposing to do it this way, that it seems to work out better, cost-wise. What is your overall flight itinerary? In other words, how are you getting home? Have you already purchased the tix or can you consider alternatives? Here’s why I ask:

I know that often people will book separate flights when they are using miles for the long-haul flights, and then plan to just pay for the less expensive short hops between European airport. That is exactly what we have done, using miles to book BA flights from Seattle to London and back in business class. Then I add the flights to and from the Continent later. But no more. I recently paid attention to the comments I have seen on other forums about the onerous Air Passenger Duty (APD) for flights departing Heathrow, and learned how much extra we have been paying for our flight home (London to Seattle) because it is based on distance. The APD does not apply to itineraries that originate outside the UK and merely connect at Heathrow, so if we start in Italy (for example) and fly to Heathrow and connect there ON ONE TICKET to our flight to Seattle, there is no APD.

https://onemileatatime.com/guides/uk-air-passenger-duty/

Turns out we have been paying an extra $500 or so for our flight home, because of the way I was booking the tix. (The taxes and fees apply even when one is booking with miles).

Although the APD is not much on an economy flight from LHR to AMS, it is something you should consider for your flight home——if you haven’t already bought your tickets.

I flew through Heathrow in October. I flew from the US to Heathrow on AA and from Heathrow to Croatia on British Airways. Although mine were all on one ticket (so I was protected), I did not have the boarding pass for my BA flight to Croatia until after I got there. I did not have to go through immigration. There was a kiosk where I could print a boarding pass before going through security. Then again, BA is huge at Heathrow so their machines are everywhere. Not sure how that would work with KLM unless you could check in online on your phone. I could not check in online for my BA flight to Croatia. (Then again...that may be because they were on an AA ticket - did not book with BA directly. I'd guess I would have been able to check in online had I bought my ticket directly from BA.)

Still, I have done what you want to do several times: bought my own ticket on from a connecting airport in Europe with only a few hours of layover. Each time I do it, I know I am taking a risk. But it has always worked out for me. Each time, I figure out exactly what would happen if I miss my connection - how much money and inconvenience will it cost? Since I've done this five or six times now, I figure if I get messed up sooner or later and have to pay a few hundred Euros for a new ticket last minute, overall it's been worth taking the risk over all of those times. I've often saved not just money but time and hassle.

Some people responding to you just don't have the same tolerance of risk that you or I might - they are responding based on THEIR risk tolerance, not yours. So keep that in mind. Understand the parameters and the consequences for you of a missed connection and decide based on that.

However, a 1:35 layover changing flights does seem a bit risky even to me. (Assume they will NOT put you on the next flight if you miss your connection - assume you will pay for a new ticket at walk-up last minute prices, though some trip insurance policies may cover some/all of the cost.) I would book the 4:05 instead since it's only 1:20 later. That makes it much more likely you will make the connection.

I do this quite often

I use frequent flyer miles to get a business class seat to LHR and then book flights or trains to where I want to go. Even with the taxes discussed above it’s often cheaper to do LHR. For example I have an upcoming business class flight to LHR I got for $2,100. A coach class flight to my final destination was the same price. A business class ticket $4,500. I’ll take my chances (heading to Spain and France. Late booking and inflexible dates=$$$$)

As I indicated I allow a minimum of 4 hours upon arrival at LHR. I do carryon only. I’ve been known to have 2 tickets. A “best case” and worst case (only if they are really cheap. I once had $40 tickets from London to Lisbon. So I bought one for about three hours after I landed and one for about seven hours after I landed. I was able to use the three hour ticket but if not, I had a back up ). I do not buy round trip tickets from LHR to wherever, that way if I miss flight one my return isn’t cancelled. And I understand and am willing to pay whatever the costs are if my plans fall apart.

On return I always arrive in London the day prior to my flight home (I was once in the Paris train station watching a woman have a total meltdown. Trains were several hours behind and she wasn’t going to get to London before her flight took off from Heathrow.)

It can work but you have to understand that if you miss a flight you are on your own

if we missed the 2:45 PM flight? Will they put us on the 4:05 PM flight without any cost?

NO

Personally I would be looking at the 510PM flight, (and wondering if it would be smarter to look at the 635PM flight)

Even the higher fare classes have the wording " Ticket changes permitted (only pay possible fare difference) "

The 'walk up' rate looks to be $295+ vs the advance rate of ~$125

How much savings are you looking at vs, a single booking all the way to AMS? You could easily end up paying $420 each for the LHR-AMS leg if you are late to LHR ( $125 for the cheap ticket bought now PLUS the $295 you pay at LHR to complete your trip to AMS) Cue Dirty Harry asking "Do you feel lucky?"

I used to do this. What made me stop was the stress involved in the last and final time doing it.
Itinerary was Cincinnati to LHR, via JFK. I got a GREAT fare from JFK to LHR and then bought a separate ticket CVG to JFK, all on Delta. Eventually there was an entire itinerary that encompassed this same trip, which was not offered when I made my initial purchase.

The week of the trip, weather forecasts began showing chance for severe weather in Cincinnati, possible affecting air travel.

If the flight is delayed and arrives JFK late, missing the connection to LHR, those people with the entire itinerary on one ticket are protected and I'm not. I'd be on the hook for buying a new ticket at walkup price.

Delta confirmed this. And while the agent said they would have worked with me on a possible solution had the delay/missed connection materialized, there was still no guarantee they would have accommodated me and no obligation on Delta's part.

After that - or maybe better stated DURING that - I decided a few hundred bucks saving was not equal to the peace of mind and I now book passage to Europe all on one ticket.

As others have said, see what the potential outcomes are, consider the cost(s) and then weigh for yourself it the savings you see now are worth the bother and costs you could encounter with a connecting flight in another terminal all in less than 3 hours time.

Your very best flight from SEATAC to Schiphol is non-stop on Delta. Both flights are less than 11 hours. If you go on Icelandair, you'll spend two more hours coming and two more hours going sitting on the ground in Iceland--for $300 difference in fares.

Yea, you can beat their airfares on Turkish Airlines through Istanbul, however you'll be spending 19 and 26 hours going and coming respectively.

You can go by the cheapest price and go on two different airlines, but price doesn't always make flights the best value. Changing airlines at a second airport can put a little pressure on you. And it's nice just going non-stop and arriving at perfect times for you to get into your hotel (and not in the dark.).

As others have said, no. If you're on a flight arriving Heathrow 13:10, the chances of you catching a flight departing 14:45 from another terminal are basically zero. You might catch a 16:05 flight, but the odds are not in your favour.

My suggestion is to spend the night in London and take the train to Amsterdam the next day.

So just because I was curious.... I ran some random dates for this.

I can see where the OP would save over $800 on a ticket doing it this way. I realize that for some of you saving $1600 on a couple of tickets is totally unnecessary but for others...

So maybe before you tell people the ONLY way to get someplace is your "best flight" which is the Delta nonstop you might consider that for some people $1600 is a LOT Of money :)

Given the delays at Heathrow and BA itself, I would give myself at least 4 hours time and only bring carryon or else you'd have to deplane, go through security get your bag and then go on the KLM.

There are times that save money but flying on one ticket means the BA is on the hook if your flight is delayed or your luggage doesn't arrive at LHR. And forget KLM offering you anything if you miss the plane because technically it is your fault for not being there on time and KLM and BA are not part of the same alliance.

Quite frankly, it all seems a very stressful start to a holiday and I'd be tempted to change both tickets to the 4:05pm(not sure why one has an earlier flight.

Update: I decided to stay overnight in London. My wife said: You'll be way too stressed and it won't be fun to be around you. Wise words. So we're heading into central London the tube. Haven't decided on a hotel. We're considering flying to AMS via Luton or London City -- because the airports are smaller and the flights are cheaper. It looks pretty straightforward to get to either airport via train. We will probably stay near St. Pancras station (or someone reasonably nearby) so we can get out to the airports without too much hassle.

Any advice about Luton v. London City?
Also, I'm having a terrible time getting British Air to send a refund that was promised almost two months ago. I was going to book with BA from London to AMS to get a few Alaska Air miles, but I'm so thoroughly fed up with their "customer experience." Maybe I'll just do EasyJet from Luton and save a lot of money.

Thanks for all of the input.

-Alex

Hi Alex,

Thanks for posting this question! We are doing much the same thing from SeaTac in May with our final destination even further away. (As someone earlier commented, saving $1600 is a big deal to some folks.) I’m waiting a bit longer for more flights to be added that cater to the “holiday” travelers expecting to have some better choices for our second flight. I’ve learned a lot from the comments here, they’ve filled in some blank spots I had. If push comes to shove we may need to spend the night in London, too. Finding good budget choices that are safe, comfortable, and well located will have to go on my to-do list.

Best of luck on your trip! And many thanks for opening up the conversation.

In mid February, we are landing at Heathrow at 6:15am from Australia with Qantas and are booked on a separate British Airways flight at 10:45am to Madrid. We will have to collect luggage, clear immigration and change terminals. We spoke to British Airways who said this should be plenty of time as our flight from Australia is one of the first to arrive in the morning and the delays at Heathrow usually occur later in the day.

We do have a Plan B. We are doing it this way because we got a great deal on business class Sydney-London return in the Black Friday sales. Sydney-Madrid added AUD$3000- to the already ridiculously expensive airfare.

Alex, have you filed a claim with BA for your refund? You can do it online; much easier than calling.

https://www.britishairways.com/en-us/information/help-and-contacts/complaints-and-claims

Your plan for an overnight in London between flights makes good sense. As for London City Airport, I have booked our next flight to Zurich from there. It looks very easy to get there using the Docklands Light Rail (DLR) from Bank station in the City of London. 21 minutes transit time.

https://www.visitlondon.com/traveller-information/getting-around-london/docklands-light-railway-network

The City is a great area to stay, with lots of history. There are a number of hotels within walking distance of Bank Station, including a very budget-friendly ( but minimalist) Premier Inn Hub.

Any advice about Luton v. London City?

Use neither, take the train to Amsterdam. Takes you direct from St Pancras to Amsterdam Centraal in about the same time as flying takes, but is a much more comfortable journey. And if bought in advance, cheaper as well. Also a lot less polluting.

But your tickets at www.eurostar.com and you can read more about the route here: https://www.seat61.com/trains-and-routes/london-to-amsterdam-by-eurostar.htm

Bottom line, Heathrow is big and busy. You can't allow too much time.