A typical line of punctuality data on the site would be presented as follows:
This data shows that for Air France flights analysed:-
- the average flight operated 13.26 minutes late;
- 73.98% of flights operated within 15 minutes of the scheduled time (also known as on-time performance or OTP);
- 4.38% of flights operated over an hour late;
- 0.30% of flights operated over three hours late;
- 13,391 flight movements were analysed when calculating the above line of data.
In all cases, unless otherwise stated, statistics relate both to departures and arrivals at UK 'Reporting Airports'.
The source data used on the site is compiled by the UK Civil Aviation Authority (CAA) in co-operation with Airport Coordination Limited (ACL). Please note that data used by Flightontime.info is sourced directly from the CAA, we do not receive any source information from ACL.
The source is gratefully acknowledged.
The actual operating times of each flight are recorded and measured against the scheduled operating time of the flight.
- Flights operating exactly on-time record a zero minute delay.
- Where the actual operating time is later than the scheduled operating time, this is recorded as a delay in minutes.
There is no credit for flights whose actual time of operation is before the scheduled time (i.e. those operating early), and these flights also record a zero minute delay.
Actual operating times of flights relate to actual airborne and landing times only.
Since the scheduled operating times of flights relate to departure and arrival at the gate, a taxi time assumption is made for each airport and is built in to the data.
Prior to January 2015, punctuality data was reported and analysed at 10 UK Reporting Airports. From January 2015, this increased to 24 UK Reporting Airports, and from January 2017 to 25 UK Reporting Airports. The taxi time assumption is shown in the following table for each of the UK Reporting Airports where punctuality data is recorded.
The method used to calculate the delay for a specific flight is best explained using the following examples.
Remember that Birmingham Airport record actual time of operation as arrival at / departure from the gate and hence no taxi time assumption is applied.
The "Within 15 minutes" / On-time Performance / OTP category is regarded as the "on-time" performance of flights. It shows the percentage of services operating "on-time".
This is simply the percentage of flights operating up to (and including) 15 minutes after the scheduled time. Since early flights are reset to zero minutes delay, these all fall into this category regardless of how early they operate.
These are simply the proportion of flights running over 1 hour late, or 3 hours late as appropriate.
For example if there are 100 flights analysed and 6 of those operate 61 minutes or longer behind schedule (the others operating within an hour of the scheduled time) then the proportion of flights delayed by over 1 hour is 6%. If 2 of those 100 flights were delayed by over 3 hours (i.e. by 181 minutes or more) then the proportion delayed by over 3 hours is 2%.
It is important to remember that the 3 hours+ late category is a sub-set of the 1 hour+ late category (i.e. these flights are already included in the 1 hour+ late category, not in addition to it).
For each row of data, the Total Flights Analysed column shows how many flight movements were analysed in the calculation of data in that row.
For example if there are 30 days in a given month, and a daily flight operates to a given destination, then for that month 60 flights will be analysed for punctuality to and from that destination (30 take-offs and 30 landings), assuming data is available for all flights.
If you have any other queries please contact us.