I wish someone had suggested a minimum of 3 hours to FCO. I was working under the 2 hour rule. I arrived 2 hours and 15 minutes before my flight. Despite having priority check in, I still only got to the gate 15 minutes before boarding started. The line for Priority check in was only 10 people deep while economy stretched half the length of the terminal. Add to that a long security line and transfer by tram to the gates in concourse G. Maybe what I experienced was unusual, but I would have felt better with a bit more time before getting in line again to board.
Marianne, Could you provide a bit of further information? Which Terminal was your flight departing from (I'm not familiar with "Concourse G")? Also, were you boarding an international flight or an E.U. flight? I departed from FCO a few weeks ago and found that some of the procedures were not what I'm used to, which took a bit of extra time. My first flight was from Rome to Frankfurt. Cheers!
The Gates G area is a Non-Schengen gate.. so it appears perhaps Mariannne checked in at Terminal 5 at FCO and then was bussed out to the Gate G area. Or if you are flying a non-US airline to the USA, you check in at T3, go through passport control, and ride the SkyTrain out to the G Gates. T3 check-in's can be a nightmare for a non-Schengen flight. Anyone who traveled to the US BEFORE Terminal 5 opened can attest to that.
Now though, all US Airlines flying direct to the US leave from Terminal 5 ... and then they dump you in the G Gates, a segregated concourse area. Most US-flagged Airlines recommend three hours for international travel. Most "domestic" (Schengen) Euro-flights recommend two hours. Because it's FCO, we ALWAYS give ourselves more time... like our experience months ago: At the FCO Airport (Again). Marianne, if you experienced chaos at FCO... that's often more the norm. Glad you made your flight.
Let me elaborate a bit more to help clarify: I used airportshuttle.it. They asked what airline I was flying and the time of my flight and they assign the pickup time as 3 hours before your flight. I thought about using the new Alitalia shuttle bus service, which also assigns a pickup time 3 hours prior to your flight, but you have to walk to Termini. So, instead i opted for the service that picks up right at the hotel. They get you to the airport within 45 minutes. If I knew then what I know now, I would have asked for an earlier pick up time. We were on a direct flight to the US, which is in Terminal 3. Our flight was was a G gate and that required taking a tram. Overall, it was a chaotic and unpleasant experience traveling through FCO and I don't look forward to doing it again any time soon.
I think this is an it-depends situation. If checking-in and/or checking luggage at the airport, then 3 hours is probably about right. If checking-in online and travelling with only a carry-on bag, then 2-1/2 hours is probably adequate. I arrived at FCO about 2 hours 15 minutes before my flight earlier this month (a bit less than planned due to Leonardo Express running late), but was at the gate at least a half hour before boarding started.