Frequent flier: President Obama boards Air Force One. (Pablo Martinez Monsivais/AP)

How can you tell when a president is in his second term? One way might be the amount of time he spends abroad.

Second-term presidents, freed from the necessity of courting voters at home — and as they’re increasingly mindful of their legacies, eager to appear statesmanlike on the world stage — tend to travel overseas more frequently than first-termers.

And it’s looking like President Obama is following the trend, with a slate of trips planned for this summer and fall.

There are the obligatory jaunts, such as the one June 17 to Northern Ireland for the G-8 Summit and then on to Berlin on June 19 to speak once more at the Brandenburg Gate.

Then he’s off the next week to sub-Saharan Africa — where he spent only one day in his first term — on an eight-day swing to Senegal, South Africa, and Tanzania from June 26-July 3. Then there’s the trip to St. Petersburg for the obligatory G-20 summit a couple days in early September.

Then there will be some time off — maybe a couple weeks at Martha’s Vineyard — in August.

By our count, he made 18 overseas trips his first term. So far he’s made two and is scheduled for a total of at least five this year, so the pace has picked up.

It may accelerate.

“Presidents gravitate more to foreign policy, and foreign travel, in their second terms,” noted American Enterprise Institute scholar Norman Ornstein.

“Add to that the fact that in today’s dysfunctional world, it is easier for Obama to deal with Vladimir Putin and Kim Jong Un than it is to deal with Rep. Darrell Issa (R-Calif.) and Senate Republican Leader Mitch McConnell.”