I am looking to book one ticket via Delta from Paris to the US, which connects via Heathrow. According to Heathrow Connections, I need to allow 1:30 to connect; arriving Terminal 4, departing Terminal 3. I will have one carry-on and one personal item.
The layover at Heathrow that I am looking to book is 1:30; which is specifically what Heathrow Connections indicates is adequate time. However, I would like to hear the thoughts and experiences of others before I book. If it makes a difference, I am looking at an early afternoon flight on a Friday, in early May; Air France arrival, Delta departure...
I've made that same connection a couple of times through Heathrow and the 1 1/2 hour timing has been sufficient, even when the first flight was a few minutes late arriving. Just don't dawdle on the walk to the connecting flight.
I always try to consider risk/reward and what are the alternatives available, factoring in all the details. Otherwise it's difficult to really answer the inevitable "is it worth it?" questions.
On one ticket, even if you miss your connection, Delta will get you home on another flight. Might be just minutes later, might be longer (depends on your ultimate destination and how frequent Delta has flights going there). How much would it matter if you get home later (or much later) - got an important meeting or event immediately upon arrival? And what's your actual destination - New York or a small city in the far west where you'll need two connections? Such details can make a big difference in the "what if" scenarios. And what are your other options besides this 90 minute connection?
Personally, I generally prefer longer connections, especially these days (for a variety of reasons) but it all depends on the details.