HK needs a full debate about how we optimally allocate scarce resources, whether it is radio spectrum for mobile phones and broadcasting, or in this case, for takeoff and landing slots at HK's airport. To facilitate that debate, Webb-site is today decrypting the Civil Aviation Department's slot data and calling for it to be added to the Data.One government portal in a machine-readable format.

Webb-site opens airport slot data
9 September 2013

With a little help from our friends at the NSA (or possibly from a single desktop PC), Webb-site is pleased to bring you greater transparency over the slot system for takeoffs and landings at Hong Kong's Airport. The Civil Aviation Department (CAD) publishes slot data on this page, but in a rather feeble attempt to limit access to the airlines of the world and not the general public, it has put passwords on all the PDF files. It can hardly be a secret if all the air transport operators can see it, but there you go.

So, without further ado, let's liberate the data. The passwords for files in the columns headed "Scheduled", "Adhoc" and "Initial Submission" is: hkg135. Presumably "Initial submission" is what the operators ask for, and "Scheduled" is what they actually get. Private planes, known by the industry euphemism of "GA" (General Aviation) have their own password to keep them apart from the rif-raff of scheduled services. So the password for the GA files  is: hkg246 (yes, they just incremented the numerals).

In the spirit of the Government's own Data.One project to disseminate Public Sector Information (PSI), we call on the CAD to remove all the passwords. In the meantime, since this is PSI, we have kept a copy of the files, and if they change the passwords, then we will make the data available on this Webb-site page instead, so what would be the point?

Having removed the passwords, the CAD should then go further and make this data available to the public as a machine-readable database rather than scanned prinouts. This would then allow analysts, economists and other academic researchers to drill down into the distribution of seats in airlines serving Hong Kong - how many are narrow-bodied, how many wide-bodied, the frequency distribution of flights and routes, actual slot utilisation at different times of day/week, slots per airline and so on. For example, by aggregating the data we could find out how many seats, rather than planes, actually take off in any hour of the day.

Slots at the airport are a precious public asset, but there is no market-based system for allocating them - it is first-come first-served, and once held, you can keep them as long as you use them. There should be an open debate about whether this produces the optimal outcome for the public interest, in terms of competition for passengers and cargo customers, and in terms of the return to the taxpayer who subsidises airport construction and expansion.

The data in some of the recent files is a bit hard to read, being a scanned printout rather than original file, and lacking column headings. However, by looking at a digital file which does have column headings (Winter 2009 Submissions, password hkg135), we can deduce what they mean (corrections welcome):

arropr Arrival air operator code (e.g. BA=British Airways). Decode these at IATA
arrflt Arrival flight number
depopr Departure air operator code
depflt Departure flight number
frdate the starting date of the schedule
todate the ending date of the schedule
dop Days in the week operating (1=monday). So 0200007 is a flight which departs on Tuesdays and Sundays
seatnbr Number of passenger seats (0 for freighters)
acft Aircraft type
orgstn Originating airport
prvstn Previous airport
arrtime arrival time
deptime departure time
overngt number of nights the plane is in HK at midnight?
nxtstn next destination airport
dststn final destination airport
arrvsvc arrival service type (guide on page 15)
depsvc departure service type

In Scheduled and Submission files with no column headings, the columns appear in the same order, but:

In the GA (mostly private jets) files, the first column is the tail number of the aircraft - you can look them up on and see tracks and photos on FlightAware. The notable thing about this is just how much of these slots are taken up with low capacity jets, typically between 10 and 20 seats. See the latest summer 2013 GA file (password: hkg246) for example (update, 10-Dec-2013: they changed the passwords - so we are republishing the data ourselves).

Update, 16-Jul-2014: A group concerned with the airport development proposals recently analysed the slot data we opened last year to show the usage patterns. The Government has changed the passwords on all the online files, even though many airports publish this data openly. In the interests of transparency and accountability, you can download the entire set of files as of 9-Sep-2013 (the original publication date of this article) at this link.

©, 2013

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