Allegiant Air More than a quarter of those flights were delayed or canceled. In fact, 27.31 percent of the airline's flights were delayed, while just 72.69 percent of its flights were on time. There you have it. Of all the US airlines, Allegiant has the most delays and cancellations.

In the current 2026 aviation landscape, cancellation rates fluctuate based on weather events and labor negotiations, but regional carriers often see the highest percentages due to their vulnerability to pilot shortages and smaller fleets. Historically, among major U.S. airlines, JetBlue and Spirit have frequently struggled with higher-than-average cancellation rates because of their concentrated operations in the congested Northeast corridor and Florida, where weather disruptions are common. In Europe, Lufthansa has occasionally topped the list during periods of intense industrial action (strikes). However, it is a grounded "reality check" to distinguish between "total cancellations" and "cancellation percentage." A massive airline like American Airlines may cancel the most flights by volume simply because they fly the most, but their rate may be lower than a smaller airline. To protect yourself in 2026, always check the "FlightAware" or "Department of Transportation" monthly reliability reports for your specific carrier before booking a "must-arrive" flight.