Overview

This tool analyses the Arrivals board, as found on Bristol Airport's website, to calculate the probabilities of various levels of conflicting traffic for your arrival.

Conflicting traffic is considered to be traffic that arrives up to ten minutes prior to your projected arrival time.

Input

Enter the flight number of your inbound sector(s) in the text box — use a space to separate multiple flight numbers — then click “Analyse”.

If you are running very behind schedule, your new projected arrival time may fall beyond the range of the calculation. In this case, you can move the range forward in time by adding a + and the number of minutes projected delay to the flight number, e.g. ezy1234+90 for a 90 minute projected delay. This procedure will also be necessary to find your flight if you are running the calculation after your scheduled arrival time; the algorithm finds your flight details by finding the first future arrival with the provided flight number.

Output

Each column of the “Probabilities” table gives the probability of a given quantity of aircraft conflicting with your arrival; for example the “≤2” column gives the probability that you will encounter two or less conflicting aircraft.

The rows of the “Probabilities” table are your own predicted delay, i.e. if you were running 10 minutes behind schedule, you would use the “10” row.

The “Arrivals considered” table shows the list of all arrivals that were considered for the calculation. Each row of the table considers a subset of this list.

Limitations

• Delays are assumed to be independent. The existence of an event that simultaneously causes delays to multiple inbound aircraft (e.g. an ATC strike or widespread thunderstorms) renders the calculation void.
• The calculation is solely based on the schedule. No account is taken of what is actually happening.
• No account is taken of the effect of departures.

Tips

• If running the calculation of your company iPad, you can share the result with the “Books” app by clicking the square icon with the up arrow. This gives you access to the results when not connected to the Internet.
• The same menu also has an “Add to Home Screen“ option if you scroll down. This will allow you to drop a shortcut on to the main iPad screen for quick access if you should so desire.

Methodology

The tool works by applying a cumulative distribution function, derived from an analysis of historic inbound delays, to scheduled Bristol arrivals in order to determine the probability that they will arrive within a given 10 minute window. These probabilities are then combined to give the probabilities of various quantities of aircraft arriving within that window. This is essentially a binomial distribution, but with different probabilities for each event.