Land and Hold Short

If you were building a mapping application that could show only (say) 20 airports on the screen at once at any given zoom level, how would you decide which airports are most important, using only publicly-available data sets? Here are some possibilities:

• Points for being in the list of the top 100 passenger airports.
• Points for having an ICAO code.
• Points for having an IATA code (rarer, so more points than an ICAO code).
• Points for each localizer and glideslope (since they’re unambiguously associated with the airport).
• Points for having a TAF.
• Points for having a METAR.
• Points for each long, paved runway.

These are all easy to measure, but I’m not sure that they capture enough of what makes an airport important for mapping purposes. Really big airports often cluster around urban areas — think of JFK, EWR, and LGA around New York, or LHR, LGW, and LCY around London. These are all busy airports, but they’re very short drives from each other (traffic permitting), so perhaps they don’t have the same kind of importance on a map as the main airport in a smaller country, the only airport serving an isolated community or an island, etc.

I’ve done some experimenting trying to measure isolation: for example, I’ve tried limiting the map to one airport in each 30×30 deg square (world level) or 10×10 deg square (continent level), but the map still ends up with huge clusters of airports in the U.S. and Western Europe and none in most of the rest of the world, and even a 10×10 square means that Toronto’s and Montreal’s main airports won’t show up (same square as JFK and EWR). What would Google do?

As I’ve mentioned before, I’m often frustrated at the lack of freely-available data for Canadian airports and airspace (and stung by the irony that most of what is available comes from the U.S.). Over the past couple of years, I’ve repeatedly started trying to put data for all airports in the Canada Flight Supplement (CFS) into an XML file or spreadsheet, but have always either given up or ran out of time before the next CFS cycle came out.

As a result, I am happy to report that someone else has succeeded where I failed. George Plews, of North Battleford SK, has managed to get all of the airports, ICAO identifiers, latitudes, and longitudes from the CFS into an excel spreadsheet, and also has it available for viewing on the web on his page Airports in Canada, together with lots of totals and statistics (for example, Ontario has 218 airports, while PEI has 4). Give his page a visit or grab the spreadsheet. Maybe the rest of us can find a way to contribute to make the spreadsheet more useful; at very least, people could commit to scanning part of the CFS each cycle for change bars, so that George can keep is spreadsheet up to date without redoing the whole thing. It would also be nice to add altitudes for the airports. Then there’s the runway data …

[Updating: on guessing -- see below] The National Air Traffic Controllers Association (NATCA) — the non-union union representing U.S. air traffic controllers — attacked plans to privatize the U.S. air traffic control system with the following statement:

Cleveland controllers alone handle more operations annually than Canada’s entire privatized system.

Cleveland airport? The airport serving that little city called the mistake by the lake? Presumably not, though it doesn’t hurt Carr’s cause to let congress think that’s what he meant. He’s almost certainly talking about Cleveland Center, one of the world’s busiest air traffic control facilities, handling traffic across an enormous part of the northeastern U.S. including two major hubs (Pittsburgh and Detroit) as well as most enroute traffic between Chicago and points east; according to their web page, they handle over 3 million operations per year.

That’s a lot, but is it more than all of Nav Canada? Not quite. According to this news backgrounder from their web site, Nav Canada handled 11 million operations in 2004.

Was Carr deliberately lying? Saying that “Cleveland” has more operations than Canada is clearly an attempt to mislead a bit (he’s hoping that members of congress will mistakenly assume he means the city of Cleveland, rather than an air traffic control unit covering much of the northeastern U.S.), but it might be going too far to call that a lie. What about the number? It might be possible to get a number bigger than 11 million for Cleveland Center simply by creatively counting all operations for all facilities under Cleveland’s airspace. For example, let’s look at an IFR flight from Detroit to Pittsburgh: Detroit tower handles the flight during taxi and take off, then passes it to Detroit departure for initial flight, which then hands it off to Cleveland center for enroute, which then hands it off to Pittsburgh arrival to set up the approach, which then hands it off to Pittsburgh tower for landing and taxi. If NATCA simply added up all of the operations for all ATC units underneath Cleveland Center, that single, short flight would count as five operations. I’m guessing that’s what happened. Nav Canada uses a single, electronic slip for flights from taxi to tie-down, so I’m pretty sure that they count each one only once.

I don’t know if it would be best for the U.S. to stick with its current socialized system or to move to a privatized, Nav Canada style system — I get good service from ATC on both sides of the border — but let’s keep the debate honest, and avoid any Enron-style counting on either side.

Update: one interesting point of discussion in the comments to this posting is my use of phrases like “I’m guessing” and “I’m pretty sure.” It’s worth noting that in both cases, the fuzzy stuff was an attempt to give Mr. Carr the benefit of a doubt — the cold facts alone look very bad for Mr. Carr in this case, and my guesses were attempts to try to find some way that his statement could have been an honest misunderstanding rather than a deliberate deception.