train

If your plane arrives on time, you should not have a problem catching any of these trains. There’s no reason to buy a ticket in advance since it’s too close to your travel date to get a discount. The 3:02 is a Regionale (€11.70) and the 3:40 is a faster Intercity (€23.50) train. I can’t find a train scheduled to leave Termini at 4:09.

2.5 hours should be plenty of time to catch one of these trains and you might even be able to catch an earlier train. Note that 2 of the 3 trains you mention depart from Roma Termini and the other (4:09) departs from Roma Tiburtina. The trains mentioned, and most of those before and after, are Regional or Intercity trains for which no discount is currently available for pre-purchase of April 27 tickets. Regional trains cannot sell out and it's unlikely the Intercity trains would, so just buy tickets at the FCO train station for the next departure to Terontola-Cortona, specifying that you don't want a Freccia train (more expensive and not much faster on this route). You should be indifferent as to whether you must change trains at Termini or Tiburtina.

Thanks Frank. So I can buy my train tickets for Terontola-Cortona at the airport station? Also can you explain what you mean about being indifferent if I need to change trains at Termini or Tiburtina? Are you saying it doesn't matter?

The 3:02 departure is risky. The 3:40 train arrives at your destination only 10 minutes later.

How long the lines will be at passport control on your arrival is unknowable. 20 minutes? 90 minutes? or?

Another factor is some planes at FCO park away from the terminal building and passengers have to take buses to the terminal, which is a slower than just walking off the plane through the tube into the building.

The fastest way from FCO to Termini is the Leonardo express. It leaves every 15 minutes and takes 32 minutes.

If I were doing this I would plan on the 3:40 train as the plausible choice.

I see no price advantage for an early purchase, so would just buy the ticket when you get to Termini

The train station at FCO has a Trenitalia ticket window, ticket kiosks and a few travel agencies. You can buy train tickets for the entire trip from the airport to Terontola-Cortona at any of these locations.

Some trains depart from Tiburtina station, so going to Termini would be an unnecessary detour, and most trains departing Termini stop at Tiburtina. So whether the ticket agent sells you tickets connecting at Termini for a train departing from Termini or tickets connecting at Tiburtina for a train departing from Tiburtina or originating at Termini makes no difference. Connections are easy at both stations.

Edit: To get a better idea of connection options and the preferred station at which to connect, use Aeroporto Fiumicino as your departure station. That will also tell you the departure time from the FCO train station, perhaps better assisting in your planning.

Or just install the Trenitalia app and purchase them from the privacy and security of your own phone exactly when you need them?

Great help all! I will install the app. Do tickets purchased via the app need to be validated?

Tickets from the app are just scanned by the conductor.

Are you saying it doesn't matter?

It does matter. The Leonardo Express runs frequently and quickly to Termini. The trains to Tiburtina are local, slow Regionale trains. And I still don’t see a 4:09. There is a 4:39 from Tiburtina.

16:09 Roma Termini
Arrival
18:28 Terontola-Cortona
Duration
2h 19'
Changes: 1

Train
Includes urban section Roma Termini - Roma Tiburtina not included in price
Section not served by Trenitalia, can be covered using urban transport (e.g. bus or underground) and not included in purchase price.
Train
Intercity 596
Price
Roma Termini Roma Tiburtina 0h 15'
Estimated time Route with urban transport
(not included in the price)

Roma Tiburtina
16:39 Terontola-Cortona
18:28 1h 49' Intercity 596

The above is from the Trenitalia site

As I read it one takes the Metro from Termini to Tiburtina and changes to the Cortona train there