Terminal IT hosts 2 airlines.
International arrivals at ONT funnel through a small IT facility
China Airlines and Volaris flights at Ontario use a compact International Terminal (IT) arrivals building rather than a full standalone departures terminal. You still check in and depart from the main terminals (T2 or T4), then on return you’re routed through this separate customs and immigration hall before stepping back into the public side of the airport.
All passport control, customs, and baggage claim for international flights sit inside this IT facility, which is physically separate from T2 and T4 by a short outdoor walk. After landing, you follow signs to immigration, collect bags from the small bank of carousels, clear customs, and then exit landside; there’s no option to stay airside and connect directly to another gate.
The International Terminal side has no catalogued restaurants, lounges, or shops, so plan on zero food or coffee once you leave the aircraft here. If you land hungry from a China Airlines long-haul or an evening Volaris run, you’re looking at vending machines or waiting until you reach T2, T4, or the curb for rideshares and nearby off-airport options.
Check-in for Volaris typically happens at Terminal 2, while China Airlines generally uses Terminal 2 as well, with boarding from those gates and only arrivals processing handled in IT. That means your outbound experience feels like a regular domestic departure from ONT, with normal security in T2/T4 and then a busier flow through the compact international arrivals space on your way back into the U.S.
Walking between ONT terminals is short but not instant: flyers report “at least 5 minutes at a quick pace” between airlines like Southwest in T4 and United in T2. If you land internationally at IT and need to re-check bags or catch a separate domestic ticket, budget 10–15 minutes from the exit of customs to a check-in counter in T2 or T4, including a brief outdoor segment.
Because the International Terminal is geared almost entirely to arrivals, there’s no lounge or quiet seating area to stretch out after a long-haul China Airlines flight or a late-night Volaris arrival. Seating near baggage claim is basic, and once you exit to the curb you’re standing in the pickup zone, so those who need to regroup usually head into T2 or T4’s ticketing halls to sit down for a few minutes.
Security for onward U.S. flights always happens in the main terminals, not in IT, so everyone connecting off an international arrival must re-clear TSA, even on a through ticket. That means picking up your checked bag at IT, clearing customs, walking to T2 or T4, re-checking bags if needed, and then heading upstairs to the security lanes tied to your next airline’s gates.
Practical tip: if you’re landing on a China Airlines or Volaris flight and then catching a separate domestic ticket, build at least 2 hours between scheduled arrival in the International Terminal and departure from T2 or T4; most of that buffer protects you from immigration lines and the walk plus TSA re-screening.