Will I be told if the airline changes the time of my customer's flight after the booking is made?

Yes, in most cases you will be told, but the message reaches you through the supplier rather than directly from the airline, so how quickly it arrives varies. When an airline moves a departure time, cancels a leg or changes an aircraft, it sends a notice into the booking system. Your portal picks that notice up and flags the booking so your team can see that something has moved and act on it.

How the flag reaches you depends on the supplier and on the type of fare. Some suppliers push these notices out quickly and in a form your portal can read straight away. Others only make them visible when the booking is looked at again, and a few send them by message to the agency rather than through the connection at all. Low cost carrier bookings are usually the weakest here, because those airlines often talk to the passenger directly and leave the agent out of the loop.

For this reason it is safer to treat the portal flag as a helpful warning rather than as your only line of defence. Agencies that handle a lot of air travel usually keep a habit of checking departures again a few days before travel, especially over holiday periods and in bad weather seasons, when schedules move most.

Ask which of your air suppliers pass schedule change notices through to the portal, and decide who on your team owns the job of watching that list and telling the traveller.