Transit times
 

I'm booking a 3-leg trip: USA-FRA-LHR-ORK. I'm unclear on where in Europe I'll need to clear immigration (more than once?), and where (in transit) I'll need to go through additional security. I'm trying to figure out where I need the extra time - FRA or LHR.

I'll have about 7 hours total, and my preference is the extra time in FRA as I'll have lounge access there (LH C), but not in LHR, I think (as arrivals lounges will be closed and my continuing flight is in another terminal, in economy, on a different airline, EI).

I could do:
5h45m FRA
2h15m LHR
or
4h45m FRA
3h15m LHR
or
6:45 FRA
1:15 LHR

Any advice would be much appreciated!

It would help to know what airlines (I suspect LH mostly?) and whether this is on one ticket or several. All of these should fairly mental to me, but I suppose option one is the best, since it gives you time for a shower and meal in Frankfurt, and you don't endanger your connection (if it is a connection) to ORK at LHR.

Option 3 is not enough time at LHR in my opinion/experience.

Option 1 is a seems to be the best balance as it allows for arrival delay from the transatlantic segment and if you're feeling bold you could venture out into Frankfurt.

Option 2 is optimized for buffers in all around.

I'm guessing (and it is a guess) that all three options have the same flights into FRA and LHR-ORK. In that case, I'd book the earliest FRA-LHR flight (your second option) because it leaves the other two flights as backups in case something goes wrong. That doesn't happen often, but it tends to happen most when you don't allow for it in your planning.

Thanks, everyone, for the feedback - much appreciated!

Due to risk aversion, I'd vote for Option 2 for someone, but for myself I'd probably take Option 1 (assuming that it's a single ticket/PNR).

Agreed. And if you're changing terminals at LHR, 1hr 15 is definitely not enough!

You will have immigration at LHR only. All transfers will have transit security, and some may involve terminal changes (depending on airlines being flown).

It seems you fly LH for USA-FRA-LHR. While this is same airline you could still have a long walk or train ride between gates at FRA (or may get lucky and arrival & departure are in the same part of the large terminal complex).