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Commercial strategy

GUIDE: Key terms for analyzing airline schedules

February 13, 2020

Whether you’re analyzing air travel flight schedules for business planning, or, reviewing airlines’ schedules databases or a data API, the […]

Whether you’re analyzing air travel flight schedules for business planning, or, reviewing airlines’ schedules databases or a data API, the terms for analyzing airline schedules, reflect aviation history. The resultant accumulated library of terms may present challenges when you’re attempting to interpret industry data across regions, companies and cultures.

To successfully analyze schedules, you may need greater fluency in “aviation-speak”. So, whether you are new to the industry, or a veteran, consult this glossary of terms which includes buzz words, shorthand and acronyms, when reviewing unique reports and airline activities.

Ancillary revenue


  • Any tickets booked for travel – whether actually flown or not in the past, or unflown (as of yet) in the future.

Booking curve

  • A curve that shows the number of passengers booked in a market (or on a particular flight), for a particular travel date or period, for an extended period of time prior to the travel date. As the travel date approaches, the number of passengers booked will increase. This increase, plotted over time, creates the booking curve. This is a key part of revenue management for airlines.

Equivalent seat-mile

  • Seats can vary markedly in size. So some airlines “normalize” ASMs into “equivalent seat-miles”, roughly: miles * square-footage/average-seat-square-footage.

Fair share

  • An airline’s expected % slice of a market based on available seats or QSI points.

Fleet management

  • The art and science of trying to optimize an airline’s network, such that the right size planes are in the right places at the right times, with high utilization (load factors) and low down time, and minimized expenses. Related to aircraft allocation and maintenance as well. This term can be associated with knowing how and when to use certain planes to get the most revenue and manage costs.

Load factor

  • Defined as RPM/ASM, or just pax/seats avail; a measure of capacity utilization, expressed in a percentage such as 85%. Qualitatively: how full your flights are, on average.

Market size

  • The number of passengers (usually expressed per day) traveling on a True Origin and Destination.


The actual passenger count on a particular segment (a specific flight).

  • On-time: Reports and data that reflect an airline/airport’s “on-time” performance – that is, whether the planes are arriving on-time or not. Often used conversationally like, “ran those on-times today”. Find monthly reports and an annual review.
  • O&D: Short for “origin and destination” – No connection between points. Otherwise known as a flight leg, or segment. This used in managing travel booking and fulfilment. Also used in air operations related to arrivals and departures.


  • Air travel industry abbreviation for passengers. Also a frequent unit used on many airline reports.


  • Short for “Per-Day Each Way”; a market’s non-directional passenger volume, calculated daily.
  • Airline Per-Day Each Way


  • Short for “Passenger Flow Model”. The art and science of estimating traffic (“passenger flow”) based on the flight network, spill, and other stated preconditions.

Revenue management – aka “RM”

  • The art and science of trying to optimize an airline’s revenue by analyzing demand and supply for airline schedules.


Short for “Revenue Passenger-Miles” – really just pax * miles, “rev pax” = “pax” usually; can also be in kilometers (“Revenue Passenger-Kilometers” or “RPK”) a measure of revenue-generating passenger volume. Do not get thrown off by “Revenue” – it’s just pax-miles. Qualitatively: how much you’re flying people in absolute terms; the amount of inventory you sold.

  • Schedule: The “Schedule” is the master listing of all scheduled flights, including origin, destination, date, time, equipment type, marketing airline, operating airline, via points, etc. Schedules are usually updated weekly.  Many industry insights originate with the schedules data, including how QSI is calculated.
  • Spill & recapture : When a flight segment hits 100% utilization (load factor), and there is still additional demand, from all O&Ds that flow over that segment, that excess demand is “spill”, as if from an overflowing cup. The recapture is the allocation of the spilled passenger O&Ds to alternate itineraries. This is a necessary step during planning and forecasting.
  • Online O&D: A sub portion of an itinerary flown all on the same airline, in sequence.
  • Sector: A nonstop flight from airport A to airport B (. Universally known as just that, aka “Wheels up, wheels down”.  There’s a new sector every time the wheels touch the ground and then lift up again.
  • Sector O&D: The origin and destination airport of each flight on a trip. It is recommended to avoid using this term – to avoid confusion with True O&D.
  • Segment
       –  Also known as a sector. One effect of passenger airline deregulation was to substantially reduce the number of multi-stop, point-to-point routes in favor of nonstop flights to hub cities at which people connect to another nonstop flight to their destination. So increasingly segments = sectors, and indeed the term “segment” has morphed into a synonym for sector.”
    –  A coupon. “Segment” derives from the old days of paper tickets and multi-stop flights.” (Implication: that a “segment” is any partial multi-stop flight.) Different meanings in different contexts. This ambiguity is why some suggest using sector in preference to segment.

True O&D

  • Where a passenger is really coming from and going to, without regard to the connecting points along the way. A True O&D is sometimes called just an O&D, or even a Trip. “True” distinguishes this from “Online O&D”

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