Originally Posted by
aristoph
Related, we almost missed our flight LHR-SEA a few weeks ago due to terrible service on the terminal shuttle. We waited nearly 15 mins all told, including the checks they do when the shuttle arrives at main terminal, and then had to run through T5C to make it at 22 min before schedule. I appreciate it would have been our fault if we had missed it, and it's a lesson learned, but that shuttle is the main reason I hate T5!
Use the tunnels, generally a little slower but you can build a predictable time into your plan.