London To Venice

National Express coaches run direct between Heathrow and Gatwick up to six times an hour and they take 75 minutes The cost is £25.
You could go into London on the underground and transfer to the Gatwick Express train, but it's easier to just take the bus.
You'll have time to get thru customs at Heathrow and make the trip to Gatwick.

I would suggest taking a later plane.

Passport Control can take 10 minutes or it can take over an hour. It depends on how busy it is. The time you arrive will be busy.

The bus to Gatwick takes about and hour depending on where at Heathrow you're picked and which terminal at Gatwick you need to get to. The fares start at £20.

A private car service starts at £50.

A taxi will cost over £100.

And then once at Gatwick you have to go through security and walk to the gate.

And what if your flight into London is late?

Checked luggage? The last time I flew to LHR happened to be with several friends. One got her bag off the carousel after 10-15 minutes, the rest of us waited over an hour.

If you are not on the same ticket, you'll have to check in for your Venice flight - another line?

Not a chance, I'm afraid.

It will depend on which carrier you use to Venice, but if it is Easyjet and you are one minute late you won't go. Count on a minimum of 90 minutes at LGW, unless you have to go to the other terminal. My last time with Easyjet to Venice from LGW a couple of years ago we checked in at North Terminal but quite a long time prior to departure we all had to board a bus at the gate which drove us around the airport to a gate at South Terminal where we went inside and then queued for another bus to take us to the aircraft.

So you need to be at LGW by 11:00. It takes anything from 45 to 90 minutes on the perpetual carpark that is the M25 around London which the only reasonable route between the two airports.

So you need to be in whatever wheeled transport you select by at least 10:00, 9:30 for safety.

But your plane is "scheduled" to arrive at 9:35, if it isn't late or rescheduled. That is wheels down, not including taxi time to the gate. Then the long walk from the gate, the likely long slow queues at Border Control Immigration (though you might get lucky) then to collect luggage, through the likely Green Channel at Customs, no time for a toilet break, and find your ground transport. At Heathrow I always like to allow an easy 90 minutes to 120 minutes.

Except you really need to be moving in your ground transport before your plane is scheduled to touch down.

Magic carpet? rare, these days. Flue powder? No fireplaces at either end.

Tricky

Did you book this on one ticket, hopefully? I can see it offered on the British Airways website, departing Dallas on American Airlines late in the afternoon (16:40) and arriving at Heathrow T3 at 9:35, then departing from Gatwick at 12:35 to Venice.

So it is a legal connection, but you will have to hustle. And if your flight is late into Heathrow, you probably won't make it. The good news is that if you are on one ticket and you miss the flight, BA should put you on the next available flight. The bad news is you would have a 4- hour wait.

Karen,

If you happen to be flying in business or first make sure you get a pass for the fast track immigration. That should get you through the immigration line in fairly short order.

Edit to add: It looks like Gatwick has expedited security screening offered as a premium service. 5 GBP per person. Just make sure you know which terminal your flight is using.

Karen,

I tend to have the same concerns as Nigel. It may be possible to make that connection, but there are too many variables so it's highly doubtful. I'm assuming you booked your LGW - VCE flight on one of the budget airlines such as easyJet?

I normally book flights like that on the same airline and one ticket, so use code share partners which eliminates a lot of hassles. If I miss the connecting flight because of delays in the earlier flight, it's their responsibility to get me on the next plane and I don't have to worry about missing connections or forfeiting my ticket on the budget airline. That's a method that has worked well for me on many trips.

Good luck!

As I have posted in the other thread 3 hours is the absolute minimum time BA will sell a Heathrow-Gatwick connection for. Whether this is a sensible connection to take considering the hassle is another matter.

That is super tight. Although I see that both legs are on BA/AA (partners with One World alliance) so presumably you are flying on one ticket. In that case you should be ok, because if your flight from the US arrives late, BA should be able to rebook you on the next flight which departs LGW at 4:20pm.