Irregular operations is the aviation industry term for a period when the published schedule stops working and airlines and airports have to recover it. The word irregular is doing quiet work there. It means the plan is gone, and what happens next is improvised.
Airline and airport staff often shorten it to IROPS. This site mostly avoids that, because the people who need these signals run cafes, hotels, shuttles and shops rather than airline operations centers.
In practice it looks like this. A flight diverts to another airport. An aircraft ends the day in the wrong city, so tomorrow morning's departure has nothing to fly. A crew runs out of legal duty hours mid-rotation. Flights are combined, retimed or canceled, and passengers are moved onto services that were already full. The original cause may have cleared hours ago.
Why it matters for airport businesses
These are the days that fill your unit at 22:30. They are not simply weather days, because the weather where you are stood may be clear all evening while the disruption arrives from somewhere else entirely, carried in on late aircraft.
They are also long. A normal delay resolves inside a shift. Irregular operations can run into the next morning, which makes it a rostering question rather than a staffing one: who opens tomorrow, and are they the same people you just kept until midnight.
How DwellTime uses it
Irregular operations is one of the conditions behind the airport disruption risk score, alongside weather, delays, cancellations and congestion. In dashboard language and in alerts the product uses plain words such as disrupted operations rather than the industry abbreviation, so that nobody has to translate a signal before acting on it.
Related terms
For what a long recovery night means at a front desk, see hotels and lounges.