@Bob If you have booked through a travel agent, why not ask him directly? That's the kind of things he is supposed to know.
Commented May 20, 2013 at 20:50 @MarcelC. In this particular case probably not: flightaware.com/live/flight/UAL1288 Commented May 20, 2013 at 21:01I'm pretty sure that you will have to change terminals. If memory serves (and things haven't changed since I flew internationally through Newark 5 years ago), there is a separate international terminal at Newark. So you'll have to take the train, which may take 20 minutes. If you don't have to re-check your luggage, you may be okay, but it will be cutting it very close. On the return flight, 40 minutes is not nearly enough, as you must go through U.S. customs, and re-check your luggage before boarding your continuing flight.
Commented May 21, 2013 at 4:22@Flimzy There is no separate international terminal at EWR. Based on the question say that they are going "home to the UK", this IS their return flight - with no customs/immigration/luggage recheck.
Commented May 21, 2013 at 7:05When looking at connections there's always 2 things you should keep in mind :
40 minutes at Newark for a Domestic -> International connection is plenty of time, presuming that your inbound flight is on time, and you're within the same terminal.
Flights from Orlando will almost always arrive in the C terminal, and flights to London will (almost?) always leave from terminal C - so you're covered there.
As for on-time - who can say? There are websites that will give you historic information, but history isn't going to control whether your specific flight is on-time or not.
So all up, the odds of you making the connection are good. Not excellent (if your inbound is more than 10-20 minutes late your odds drop significantly), but still good.
So what happens if you miss the flight?
Newark is a very major United hub. They run multiple flights to London from there every day - especially in the evenings when flights depart as frequently as 1-2 hours apart! Depending on the day, there will likely be 2 other direct flights to London after yours - and the airline will happily move you to one of those flights presuming there are seats available.
Yes, it's possible there won't be seats available - but odds are there will be, especially as it's likely someone from one of the later flights actually went "standby" on your original flight.
Yes, it's possible that you'll end up separated from your traveling companions, and in a middle seat.
But you'll almost certainly get on!
So what should you do? Presuming you've already booked, I'd say go with it. Changing flights is not going to be cheap, and the odds of them letting you do it for free due to the short connection are almost zero.
If you haven't booked, then it comes down to cost. If you can get a later flight to Heathrow for the same price, I'd probably do it. It'll get you in an hour or two later, but it'll be worth it for the piece of mind. But if it's going to cost more, then I'd stick with the 40 minute connection - worst case you miss the flight and end up on a later one anyway!
If you were connecting to a location with less frequent services (eg, one-a-day rather than every few hours) then this would be a very different story! In that case, make sure to allow yourself enough time as having to wait an extra 24 hours for the next flight isn't fun.