Terminal transfers are the single most underestimated part of a connection. On a map the terminals look adjacent. In reality you might need a shuttle that runs every twenty minutes, a second security screening, and a ten minute walk at each end.
Assume the transfer takes longer than the airport claims, and you will rarely be caught out.
Airside versus landside transfers
An airside transfer keeps you inside the secure zone. It is quick, usually a train or a covered walkway, and involves no new security check. A landside transfer means exiting, taking a bus or train on public roads, then checking in and clearing security again, which can easily take an hour with queues.
Which one applies depends on the airport and sometimes on the specific pair of terminals, so look it up rather than guessing.
Step by step
Step 1: Confirm both terminals on the day
Terminal assignments change, especially with codeshares and seasonal schedules. Check the departure board or the airline app after landing rather than relying on the ticket printed weeks ago.
Step 2: Follow transfer signage, not exit signage
If an airside connection exists, the signs say transfer or connecting flights. Following exit or baggage claim signs is the classic mistake, and once you are through immigration, getting back means starting over.
Step 3: Budget the real time
As a rough planning rule, allow fifteen to twenty minutes for an airside train transfer, and forty five to seventy five minutes for a landside bus transfer including security. Add more at peak hours or in very large hubs.
Step 4: Ask if you are unsure
Airline staff at the arrival gate can tell you the correct route in ten seconds. In airports with multiple operators, the answer sometimes depends on which airline you are flying next, so mention the flight number.
