Connections, stopovers, open-jaws and ARNK, explained

A gap between two flights can mean very different things. Getting the language right keeps an itinerary honest and a client unconfused.

Connection vs. stopover

Both describe a gap between two flights at the same airport, and the difference is about duration and intent.

Connection

A short changeover — conventionally under 24 hours on an international itinerary — where the traveller is just passing through on the way to their real destination. The transit time is worth noting (it affects whether the connection is comfortable), but the traveller doesn't experience the layover city as "part of the trip."

Stopover

A longer break — 24 hours or more — where the traveller is meaningfully staying in that city before continuing. A stopover can change what the fare allows and is worth calling out clearly. Some airlines even market deliberate stopovers as a feature.

The 24-hour line is a convention, not a law of physics — domestic itineraries often use four hours as the threshold. What matters is communicating intent: is the traveller changing planes, or spending a night?

When a "gap" is neither

On a round trip or a circle itinerary that loops back to where it started, the gap at the turnaround point isn't a connection or a stopover in the usual sense — it's simply the traveller's stay at their destination, however long. Applying the 24-hour "stopover" label mechanically to that gap is misleading: nobody describes a week's holiday in Rome as a "168-hour stopover." A good itinerary presentation recognises the turnaround and doesn't clutter it with a transit duration. Likewise, a deliberate multi-day stay part-way through a one-way, multi-city trip is a planned stay, not a connection to flag — the traveller already knows they're staying.

Open-jaw

An open-jaw is a round trip where one end doesn't match. The two common shapes:

Destination open-jaw: fly into one city and home from another (e.g. out to Rome, back from Venice) — the traveller covers the Rome–Venice leg by their own means.
Origin open-jaw: the outbound and return use different home cities.

Open-jaws are normal and often cheaper than two one-ways. The "jaw" — the overland gap the traveller arranges — is exactly what an ARNK segment marks.

ARNK

ARNK stands for "arrival unknown" (often read as "arunk"). It is a surface segment — a placeholder inserted into a PNR to bridge a gap in the flown routing, such as the overland leg of an open-jaw. If a passenger flies into Rome and out of Venice, the Rome→Venice portion appears in the record as an ARNK so the itinerary remains continuous for ticketing and fare purposes. It represents no flight; it simply tells the system "the traveller gets from A to B on their own here."

Why the distinction matters in a quote

To a booking system, these are structural facts. To a traveller, they are the difference between "you change planes in Doha for two hours" and "you have an overnight in Doha," or between "you fly home from where you arrived" and "you make your own way across to the other airport." Presenting each one in plain language — and not, say, labelling a three-day stay as a stopover with an unhelpful hour count — is what turns raw routing into a quote a client trusts. PNRpro classifies each gap and presents short connections, genuine stays and turnaround points appropriately, so the itinerary reads the way a traveller thinks about it.

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