The Civil Aviation Authority publishes punctuality statistics for the following airports: Aberdeen, Belfast City (George Best), Belfast International, Birmingham, Bournemouth, Bristol, Cardiff Wales, Doncaster Sheffield, Durham Tees Valley, East Midlands International, Edinburgh, Exeter, Gatwick, Glasgow, Heathrow, Isle of Man, Jersey, Leeds Bradford, Liverpool (John Lennon), London City, Luton, Manchester, Newcastle, Southampton, Southend and Stansted.
Full and Summary Analysis is prepared with the co-operation of the airport operators and Airport Coordination Ltd. Their assistance is gratefully acknowledged.
Reasons for changes in the punctuality metrics
The changes in the punctuality statistics were prompted and informed by:
- recent evidence on the importance of punctuality information for consumers; and
- the outcome of the CAA's Punctuality Review
Evidence of consumer demand
Evidence has recently come to light suggesting that the CAA needs to widen the scope of the data it publishes on on-time light performance and to improve its quality. CAA consumer research demonstrates that consumers consistently rate information on flight performance as important. Regarding on-time performance, research conducted by the CAA reveals that consumers are most concerned about their flights arriving at their destinations on time. In light of this evidence and in order to ensure that punctuality reporting is useful to consumers, the CAA decided to:
- collect cancellation data from airports and include relevant metrics in the CAA's punctuality statistics reports, published monthly and annually
- increase the granularity of existing punctuality metrics and include additional relevant metrics in the CAA's punctuality statistics reports
Our Punctuality Review
In early 2017, we began a review of the methodology we follow to calculate delay with the view to ensuring that our punctuality metrics are accurate, reliable and present a fair picture of aviation performance.
The review recommended that the CAA should move from an estimated gate delay approach to calculating actual gate delay. This was enabled by the introduction of AvStats which made it possible to calculate actual gate delay by collecting actual gate times from airports; thereby removing the need to use estimated taxi times. As a result, errors involved in calculating gate delay are minimised and the accuracy of the CAA's reported on-time data is increased.
These notes relate to publication covering the period January 2018. For information about publications prior to January 2018 please see individual publications from that period.
Calculating punctuality
The measure of punctuality is derived from the difference between actual gate time and planned gate time. Actual gate time refers to the “off-block” time on departure and “on-block” time on arrival.
Actual gate times of operation are supplied by airport operators to the CAA. The planned times are supplied by Airport Coordination Ltd or the airport operators themselves and include changes made up to 30 minutes before operation.
The actual gate time is not a mandatory field but is required to calculate punctuality. In instances where the actual gate time is not available it has been derived from the actual runway according to the following taxi time assumptions.
| Airport | Arrivals | Departures | Airport | Arrivals | Departures |
|---|---|---|---|---|---|
| GATWICK | 10 | 17 | DONCASTER SHEFFIELD | 7 | 7 |
| HEATHROW | 10 | 25 | DURHAM TEES VALLEY | 6 | 5 |
| LONDON CITY | 3 | 15 | EAST MIDLANDS INTERNATIONAL | 8 | 8 |
| LUTON | 6 | 12 | EDINBURGH | 8 | 10 |
| SOUTHEND | 5 | 8 | EXETER | 8 | 10 |
| STANSTED | 10 | 13 | GLASGOW | 7 | 10 |
| ABERDEEN | 6 | 7 | ISLE OF MAN | 5 | 10 |
| BELFAST CITY (GEORGE BEST) | 7 | 6 | JERSEY | 8 | 3 |
| BELFAST INTERNATIONAL | 5 | 5 | LEEDS BRADFORD | 7 | 11 |
| BIRMINGHAM | 10 | 10 | LIVERPOOL (JOHN LENNON) | 10 | 6 |
| BOURNEMOUTH | 6 | 7 | MANCHESTER | 11 | 15 |
| BRISTOL | 7 | 7 | NEWCASTLE | 5 | 8 |
| CARDIFF WALES | 9 | 5 | SOUTHAMPTON | 7 | 9 |
No account is taken of the different taxiing times associated with the terminal building used.
Only obvious mismatches between the actual gate time and planned gate time have been reconciled.
Airport Coordination Ltd is responsible for allocating slots to airlines operating at many of the airports included in the punctuality reports and their data are assessed with the “planned data” provided by the airports. Below is a list of airports at which Airport Coordination Ltd data is used to audit “planned data” reported by the airport Authorities
Aberdeen, Belfast City (George Best), Belfast International, Birmingham, Bournemouth, Bristol, Doncaster Sheffield, Durham Tees Valley, East Midlands International, Edinburgh, Gatwick, Glasgow, Heathrow, Jersey, Leeds Bradford, Liverpool (John Lennon), London City, Luton, Manchester, Newcastle, Southampton, Stansted.
For Cardiff and Exeter, Airport Coordination Ltd “planned data” is used and assessed in conjunction with the airports actual gate times as they do not provide planned gate times.
Airport Coordination Ltd does not coordinate slots for airlines at for the airports listed below and the “planned data” is not audited.
Isle of Man and Southend.
The inclusion of cancellation data and expansion of the punctuality time bands
The number of flights cancelled is now included in the reports. For these purposes, the CAA defines a cancellation as:
“the non-operation of a previously planned flight, announced less than 24 hours before or after its scheduled departure time”
Additional fields have been introduced to the punctuality time bandings. The additional fields are as follows:
1) Number of cancelled flights: The inclusion of the number of flights cancelled to on-time performance metrics
2) Cancellations as a proportion of all flights: The inclusion of the proportion of flights cancelled to on-time performance metrics
Additional on-time performance bands as a proportion of all flights:
3) The existing “Early to 15 minutes late” band is split into three sub bands: Flights more than 15 minutes early percent, Flights 15 minutes early to 1 minute early percent, Flights 0 (zero) to 15 minutes late percent.
- The existing “Between 61 and 180 minutes late” band is split into “Between 61-120 minutes late” and “121-180 minutes late”.
The new fields (and bands) are shown below (incl. Cancellations and unmatched flights)
| New punctuality fields |
| Number flights cancelled |
| Flights more than 15 minutes early percent |
| Flights 15 minutes early to 1 minute early percent |
| Flights 0 (zero) to 15 minutes late percent |
| Flights between 16 and 30 minutes late percent |
| Flights between 31 and 60 minutes late percent |
| Flights between 61 and 120 minutes late percent |
| Flights between 121 and 180 minutes late percent |
| Flights between 181 and 360 minutes late percent |
| Flights more than 360 minutes late percent |
| Flights unmatched percent |
Further notes
- The Full Analysis reports exclude data for operators for whom we do not have consent to publish. Therefore, the total number of flights within the Full Analysis reports may differ when compared with the Summary Analysis reports.
- The “Full Analysis Arrival Departure” report includes an Arrival/Departure column whereas the “Full Analysis” report includes both arriving and departing traffic aggregated together.
- The number of unmatched actual flights represented those air transport movements which actually took place at the airport but for which no corresponding planned flight was found. The reasons for this would normally be: (a) the flight was a diversion from another airport; (b) the flight was not recorded with Airport Coordination Ltd or airport; (c) the flight was a short-haul flight more than one hour before the planned time; (d) the flight was planned to take place in the previous month.
- All-cargo services, oil rig and air taxi services are excluded from the analysis.
- Positioning, private, corporate, military, local and other non-air transport movements are excluded from the analysis.
- Flights are allocated to airlines according to the flight prefix of the service. Therefore, in the case of a sub-charter service, the flight is shown against the airline commercially responsible for the service. In the case of franchise operations, the service is recorded against the operating carrier.
- The aircraft origin/destination represents the final point on the service. An aircraft serving more than one point on the route is therefore shown once only in the tables.
- Some domestic routes listed in this publication may be domestic sectors of the international service.
- Flights between any two of the airports included (e.g. Heathrow-Manchester) are counted twice.
- Care should be taken in comparing the average delays during the current year with the average delays during the previous year. The number of flights reported for a given period may be reviewed and changed in subsequent publications. The average may be calculated on a small number of flights in either year.
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