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Cirium CMO, Mike Malik

Air operations, Expert view, On-Time Performance

How the data used to measure airline punctuality adds up

March 5, 2020

Cirium has a proven track record of reporting on OTP results for more than 11 years – the longest of anyone in the industry.

NOTE: On June 10, 2021 — Cirium resumed The On-Time Performance Report. The report was suspended in early 2020, as flights were impacted by the COVID-19 pandemic.

The market for tracking and reporting on airline and airport on-time performance (OTP) around the world is becoming more crowded. New players are entering this highly informative field, and all have adopted methods to calculate, interpret and present the results in their own way. Most of these methods and processes are there to do one thing: to fix gaps in their data.

They all purport to adhere to a common set of guidelines that are built around the same IATA & DOT rules for measurement of on-time performance. So why is it the results often differ from company to company? How do you trust one set of results over another? Who has the right numbers? And does it matter?

Let’s clear up some common misconceptions about OTP, explain the reasons why Cirium’s data is different and why we know it is the most accurate.

Measuring airline punctuality

The basic measurements are:

  • D0: Departures exactly on time or early
  • A0: Arrivals exactly on time or early
  • A14: Arrivals within 15 minutes of scheduled time
  • B0: Flights operating in scheduled block time (gate to gate)

How Cirium measures airport and airline on-time performance

Cirium has a proven track record of reporting on OTP results for more than 11 years – the longest of anyone in the industry. So, based on our historical experience, we have some authority in this area. We try to stay true to the industry definitions of OTP and make sure we represent the data in a transparent and consistent way.

Looking back at 2019, we monitored well over 38 million published passenger flights. But erring on the side of caution to ensure our data was rock solid, we reported to the media that we monitored a slightly lower figure of over 35 million flights. This is conservative but still accurate.

Other brands, meanwhile, reported they monitored over 58 million flights with no explanation of what this number includes. That’s blatantly misleading. We can only assume that claiming a larger number would lead consumers to conclude their results had greater credibility.

It’s this boastful behavior and unsubstantiated claims which lead to confusion in the media and the industry. This inflated number of 58 million includes “marketed flights”, which are codeshares and not on the original airline’s own aircraft. It’s double counting and just plain wrong.

There are industry experts who say that companies reporting OTP should get together and confer before publishing results. While this is a logical suggestion, it would mean sharing our data with a less credible company which is cavalier enough to mis-quote their own data. Knowing how hard it is to earn credibility and how easily it can be lost, I think we’re wise to pass on the suggestion.

We know the inherent strength of our data – that it is quality controlled and verified. Diluting it with someone else’s poor-quality data would not benefit the industry and would surely damage us. It’s these kinds of issues that cast doubt on the entire reporting process and why we are bringing it to light.

How Cirium data delivers the true OTP story

And precisely why data supplied by other providers doesn’t always add up…

  • Total Number of Global Flights – Cirium counts individual commercially operated flights to reflect the most accurate number of scheduled flights. However, codesharing between airlines, where they market and publish a flight as part of their own schedule when it’s in fact owned and operated by a completely different airline is commonplace. But counting the total number of codeshare flights artificially inflates the flight count. It’s not accurate and it doesn’t reflect the true number of scheduled flights operated by airlines.
  • Arrival OTP Metric – Cirium adheres to the industry-standard definition of on-time arrivals as flights that arrive within 15 minutes of scheduled “Gate. Arrival”. Using different arrival times other than “Gate Arrival” to measure OTP, such as runway arrival, is inaccurate and does not conform to industry standards. We know use of “Runway Arrival”time often leads to overstated OTP numbers. When Cirium reviewed another OTP provider’s method, we noticed they don’t specify that they use gate arrival time – just arrival. We suspect that they may use whatever arrival data they have, such as runway or gate. The difference between runway and gate arrival times can be anywhere between five and 30 minutes – enough to seriously skew the results. But whatever they use, the result is the same; they don’t match the true OTP and could be over-stated.
  • Departure OTP Metric – As with Arrival OTP Metric, Cirium uses the industry standard departure within 15 minutes of scheduled “Gate” departure. Using departure times other than the reported “Gate” departure time is simply inaccurate.
  • Calculation Method –Cirium is fanatical about data accuracy; and we make no apology for it. We calculate OTP only on flights where we have actual “Gate Arrival” or “Gate Departure” time information. When gate time data is not present for a flight then it’s excluded from out data – it’s as simple as that. To reduce the margin of error, we only publish OTP metrics for an airline when we have actual gate arrival times for a very high percentage of an airline’s scheduled flights  – 85-95% depending on the airline category.
  • Data Curation –Cirium curates the flight status data for OTP from more than 600 sources of real-time flight information. This includes airline direct partnerships, airports, global distribution systems, positional data, Civil Aviation Authorities/ANSPs, proprietary data partnerships and the Web. We validate and corroborate flight information across multiple sources to ensure highest level of accuracy. This flight data is the fundamental foundation to our OTP program.

As you can see, Cirium has high standards for data collection and presentation. We believe we have the best OTP data in the world. To further bolster the credibility of our data, we know we are the only entity which has a completely independent board of advisors for OTP. This is comprised of industry experts who have an unbiassed view of the industry and have a remit to ensure accuracy and proper representation of the information.

All of this adds up to Cirium being the number one source for airline and airport on-time performance.


Learn more about the Cirium On-Time Performance Report.

You can see the full Cirium On-Time Performance Review 2019 here.

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