We fly into Heathrow from Rome on 7/29/07 at 11:25am on Alitalia and depart on United to San Francisco at 2:10pm. They are separate tickets, so we will have to collect our bags from Alitalia and check them with United.

Have I left enough time or should I reschedule one of the flights?

Another question: How much time should we leave to change planes? There's another flight that arrives at 9:30 instead of 11:30. Is 4 1/2 hours reasonable?

There's no easy answer to this.

Ordinarily, if United has online checkin (OLCI), it really oughtn't to be a problem. Right now though, with security at "critical", you might not check in and get through security, especially if United doesn't allow OLCI, in 2.5 hrs

Who knows what security will be like in four weeks? "Critical" levels rarely last more than a few days, but can be reinstated on the basis of one intercepted email. I'd get the earlier flight.

I agree. 2.5 hours is <i>probably</i> enough, but anythng can pop up and LHR can be a real zoo. I'd definitely take the earlier flight. (BTW - Alitalia might check your bags through. But even so, I'd take the early flight)

Many thanks. That's just the feedback I was hoping for.

United doesn't allow online check in when traveling inbound internationally. I discovered this a couple weeks ago when I tried to check in online in Paris.