Flight Connection Risk Estimator

Minimum connecting time, abbreviated MCT, is a published per-airport, per-carrier, per-transfer-type value carried in the IATA Standard Schedules Information Manual, and airline reservation systems refuse to sell an itinerary shorter than it. Domestic values typically run 30 to 45 minutes at small stations and 45 to 75 minutes at large hubs, while international-to-domestic transfers that require immigration, baggage reclaim and re-check commonly sit at 90 to 120 minutes at airports such as Heathrow, Dubai or Narita. MCT assumes an on-time arrival, a working jet bridge and a normal walking pace, so it is a floor rather than a plan. The success probability treats inbound delay as a random variable and asks how often it stays below the available slack, slack being layover minus MCT. Airline delay distributions are strongly right-skewed - most flights land within a few minutes of schedule while a thin tail runs hours late - so the normal approximation used here is a rough fit that tends to be optimistic about the tail. The US Department of Transportation counts an arrival as on time if it is within 15 minutes of schedule, a convention that hides short delays which still consume a tight connection. Terminal changes add roughly 15 to 45 minutes depending on whether the transfer stays airside, and a connection sold on two separate tickets carries no rebooking obligation at all, which is why the expected-cost figure matters as much as the probability.

Interline connections became a routine planning problem after the International Air Transport Association was founded in Havana in 1945 and began standardizing schedule, fare and ticketing data among member carriers. Minimum connecting times were codified into the Standard Schedules Information Manual, the reference that lets a reservation system anywhere in the world judge whether a given transfer is legal to sell. Connections mattered far more after the US Airline Deregulation Act of 1978, when carriers rebuilt their networks around hub-and-spoke banks, deliberately timing waves of arrivals and departures so that a large share of passengers changed planes rather than flying point to point. Measurement followed the network change. The Department of Transportation began requiring large US carriers to report on-time performance in September 1987 after a year of heavily publicized delays, and the Bureau of Transportation Statistics has published that data monthly ever since, adding causal categories - air carrier, extreme weather, national aviation system, late-arriving aircraft and security - in June 2003. Late-arriving aircraft consistently accounts for roughly a third of delay minutes, which is the statistical fingerprint of delay propagating forward through an aircraft rotation over the course of a day. Third-party trackers such as FlightAware commercialized the feeds during the 2000s, and carriers now run comparable models internally when deciding whether to hold a departure for connecting passengers.