Airport Codes

January 17, 2004 12:18 AM

Why is there sometimes an "X" added on the end of a three letter airport code? i.e. LAX

I thought that it might stand for international, but that doesn't make sense, because ORD (Chicago O'Hare) and many other airports are international and don't have X on the end. Anyone know? I live in PDX, and I always get asked why there's an X when I'm travelling and refer to Portland as PDX.

posted by SpecialK to Travel & Transportation (19 answers total)

My best guess is that it is used as a filler letter where a TLA makes no sense.

Besides, a lot of airports have really stupid letters. For example, Pearson Airport in Toronto, Canada has the letters YYZ. It's the zipper airport! :-)
posted by shepd at 12:21 AM on January 17, 2004

how about for Xchange?
posted by filmgeek at 12:42 AM on January 17, 2004

It's what the cryptographers call a null, a meaningless letter (typically X is used but sometimes Q or Z) added to fill out a group of letters in ciphers that require groups of a certain number of letters (such as many transposition ciphers). There's no ciphering going on here, but the principle is the same.
posted by kindall at 1:02 AM on January 17, 2004

Actually YYZ would be the RUSH airport! In Canada - appropriately.
posted by davidmsc at 1:40 AM on January 17, 2004

There is a meaning to the X according to this. The X was added to existing weather stations when three letter acronyms were airport codes were first assigned.
posted by rdr at 3:07 AM on January 17, 2004

Slightly off-topic, but why do all Canadian airport codes start with Y? I don't think any other country has all of its airport codes starting with a single letter...
posted by Johnny Assay at 7:08 AM on January 17, 2004

Thanks for that link, rdr.
posted by carter at 7:10 AM on January 17, 2004

ORD is for "Orchard," btw. (Original use for O'Hare's original land.)
posted by thomas j wise at 7:46 AM on January 17, 2004

A little fun: Spokane International's is GEG for Geiger Field. Yes. That Geiger... during the Cold War we liked to joke that we were number three on the lists of places to bomb — DC, Norad, Spokane.
posted by silusGROK at 7:54 AM on January 17, 2004

More on ORD.
posted by SteveInMaine at 7:55 AM on January 17, 2004

The Ottawa airport is YOW ... yyyyyYOW!!
posted by Succa at 10:12 AM on January 17, 2004

It's not that we were far down on the list, it's just that at the time, Y wasn't much used in codes worldwide, so Canadian aviation authorities chose it as a basis for creating uniform and distinctive nationwide codes.

Oh, and Toronto was formerly the City of York...hence the middle Y. No ideas on the Z, though.
posted by xiffix at 10:37 AM on January 17, 2004

RDR - Awesome answer -- that article told me everything I'd wondered about from listening to the pilot chatter on United flights.
posted by SpecialK at 12:18 PM on January 17, 2004

Another thing I've noticed is stripping of various letters (often just the first) from city names.

ACT—Waco, Texas
AZO—Kalamazoo, Michigan
APF—Naples, Florida
EYW—Key West, Florida
EWR—Newark, New Jersey
ILM—Wilmington, North Carolina
HPN—White Plains, New York
ICT—Wichita, Kansas
posted by oaf at 1:16 PM on January 17, 2004

Thanks, rdr! I grew up in Spokane and never knew Spokane Intl. was once Geiger Field, thus always wondered why our code was GEG.
posted by Lynsey at 2:30 PM on January 17, 2004

Now can anyone solve the mystery of why Portland (ME) Int'l Jetport = PWM??
posted by anastasiav at 3:04 PM on January 17, 2004

It's Portland-Westbrook-Municipal. From the history page on PWM's Web site.
rdr, your link is terrific, btw.
posted by Happydaz at 8:40 PM on January 17, 2004

My fave Airport code - EEK. It's the name of the airport and the town in Eek, Alaska, (aka Eek, AK) the only Airport code that is also name of the town.
posted by kokogiak at 12:25 AM on January 18, 2004

If anyone is really interested in airports, goto Landings.com - you can look up the physical data on a lot of airports and plot flight info - such as weather, elevation changes, and it will plot a map. Very cool.
posted by plemeljr at 7:36 AM on January 19, 2004