Why Are Dulles And Houston IAD and IAH?

burchfiel · Wed Jan 14, 2015 10:26 pm

I was wondering why Dulles's IATA code is IAD, rather than DIA. After all, no one refers to the airport as "International Airport Dulles."

It doesn't appear that any airport is currently assigned DIA. WAS WIA (Washington International Airport) also could have worked. Were people worried about confusion with Stapleton?

Likewise, why IAH and not HIA? HIA is taken now, but HIA only opened in 2008 -- I don't know if the code was available before that.

I admit this is not the most important topic on the Airliners.net forums, but I was just curious.

bpat777 · Wed Jan 14, 2015 10:31 pm

I've wondered that about IAH myself. I figured it was short for International Airport of Houston. IAD maybe International Airport of District of Columbia?

tzsfo · Wed Jan 14, 2015 10:34 pm

Here is an old thread I found on the subject - it at least has some guesses.

What Does The IA Stand For In IAH And IAD? (by IloveBOI Aug 1 2003 in Civil Aviation)

opethfan · Wed Jan 14, 2015 10:37 pm

I've heard before that authorities don't like airports in the same metro area to have the same first letter of their code because it can cause confusion / mixups with tickets and bag routing. Of course, that isn't how it plays out in Canada or in London (LGW and LHR) or even in LA (LAX and LGB) but it's understandable.

Quoting bpat777 (Reply 1):
IAD maybe International Airport of District of Columbia?

I'd assume the D stands for Dulles.

stratacruiser · Wed Jan 14, 2015 10:49 pm

Before being renamed for the 41st President, IAH was Houston Intercontinental....or Intercontinental Airport Houston for those assigning the codes at IATA.

Dave

Sooner787 · Wed Jan 14, 2015 10:52 pm

it's a conspiracy to trip up future travel agents and airlines employees LOL

redzeppelin · Wed Jan 14, 2015 10:55 pm

Quoting Sooner787 (Reply 5):
it's a conspiracy to trip up future travel agents and airlines employees LOL

You might be right:
The night before an early morning flight out of IAH (about 3 years ago), I received an automated phone call from DL informing me that the flight was cancelled. I jumped online to check my rebooking options, only to find that there were no seats available on any DL flights out of IAH. I called in to Delta, and the agent offered me alternates out of AUS or DFW before unexpectedly finding me something out of Houston. She rebooked me, I hung up, and then I checked the new itinerary in my email. She had booked me out of IAD! I called back later and got it worked out.

alfa164 · Wed Jan 14, 2015 11:09 pm

Quoting Burchfiel (Thread starter):
I was wondering why Dulles's IATA code is IAD, rather than DIA.

For many years, Denver International was called "DIA" publicly, even though its airport code was DEN. I don't know if that might be one reason, but it is a possibility.

TWA772LR · Wed Jan 14, 2015 11:15 pm

Quoting redzeppelin (Reply 6):
She had booked me out of IAD!

A certain international airline I used to work for in IAH had a baggage mishap some months ago and among the fiasco were a handful of bags that were supposed to go ABC-XYZ-IAD! I wonder how many IAH bags ended up in IAD.

FriendlySkies · Wed Jan 14, 2015 11:38 pm

Quoting alfa164 (Reply 7):
For many years, Denver International was called "DIA" publicly

It still is, at least in Colorado.

1337Delta764 · Wed Jan 14, 2015 11:41 pm

Quoting alfa164 (Reply 7):
For many years, Denver International was called "DIA" publicly, even though its airport code was DEN. I don't know if that might be one reason, but it is a possibility.

A similar situation occurs in Orlando, where the local media refers to MCO as "OIA".

gdg9 · Thu Jan 15, 2015 12:04 am

I think ICAO rules prohibit airports within 200 miles of each other from having the same first two or last two letters in the code, so IAD couldn't have been DIA when created.

This link has some possible explanation, and touches on the 200 mile issue. http://www.skygod.com/asstd/abc.html Some of this may be urban legend, but still of interest.

burchfiel · Thu Jan 15, 2015 12:18 am

Quoting gdg9 (Reply 11):
This link has some possible explanation, and touches on the 200 mile issue. http://www.skygod.com/asstd/abc.html Some of this may be urban legend, but still of interest.

That's a fascinating article, thanks for sharing. I had no idea that new codes can't start with N, K, or W.

tymnbalewne · Thu Jan 15, 2015 12:26 am

Re: IAD....I seem to recall that, back in the day when ATC strips were handwritten, DIA and DCA could easily be confused.

777Jet · Thu Jan 15, 2015 12:34 am

Quoting Burchfiel (Thread starter):
I was wondering why Dulles's IATA code is IAD,

Quoting Burchfiel (Thread starter):
Likewise, why IAH

Thanks for starting this thread.

I have always wondered the same thing regarding IAD & IAH.

At least I now know why

Miami · Thu Jan 15, 2015 12:53 am

Quoting 777Jet (Reply 14):

Same. Very interesting.

There's lots of airports with interesting, yet confusing IATA code.

citationjet · Thu Jan 15, 2015 12:59 am

Here is a nice video that explains some of the rules for airport codes.
http://www.youtube.com/watch?v=63NLvAz5CDg

thomasphoto60 · Thu Jan 15, 2015 12:59 am

Quoting Miami (Reply 15):
There's lots of airports with interesting, yet confusing IATA code.

Sioux City has been trying for years to get their code SUX changed, with no luck.

jb1087xna · Thu Jan 15, 2015 1:00 am

Quoting Miami (Reply 15):
There's lots of airports with interesting, yet confusing IATA code.

Though I have to call it my home airport, XNA definitely falls into the characteristic of... interesting.

smokeybandit · Thu Jan 15, 2015 1:07 am

Quoting tymnbalewne (Reply 13):
Re: IAD....I seem to recall that, back in the day when ATC strips were handwritten, DIA and DCA could easily be confused.

That's how I've understood it, too.

OzarkD9S · Thu Jan 15, 2015 1:21 am

I remember reading an article in ATW back in the late 80's or 90's that a few Republican Congressmen were floating around an idea to rename Dulles after Dwight D. Eisenhower and change the code to IKE. Nothing much came of it of course.

sparky35805 · Thu Jan 15, 2015 1:24 am

Someone mentioned Orlando as MCO.Airlines started serving it when it was still McCoy Air Force Base in the very early 1960s.

TWA772LR · Thu Jan 15, 2015 3:14 am

Quoting thomasphoto60 (Reply 17):
Sioux City has been trying for years to get their code SUX changed, with no luck.

Its a good thing no airline flies Sioux City to Dickinson, ND.

a380787 · Thu Jan 15, 2015 3:18 am

Quoting TWA772LR (Reply 22):

Or fly Fukuoka to Montreal

IAHflyer97 · Thu Jan 15, 2015 3:21 am

Quoting a380787 (Reply 23):

Fresno to Fukuoka?

steeler83 · Thu Jan 15, 2015 3:31 am

Quoting thomasphoto60 (Reply 17):
Sioux City has been trying for years to get their code SUX changed, with no luck.

That... well sux.

Quoting IAHflyer97 (Reply 24):
Fresno to Fukuoka?

Aw man... something funny I read in an email about some of the dumbest people to ever hold political office came to mind.

Some guy was complaining about why his baggage sticker said he was "fat." The ticketing agent was trying to tell him that FAT was the IATA code for Fresno's airport.

Then you posted that statement and I just cracked up.

"FAT-FUK?! Are you kidding me?!!"

Thanks for the laugh.

rampart · Thu Jan 15, 2015 3:32 am

Quoting alfa164 (Reply 7):
For many years, Denver International was called "DIA" publicly, even though its airport code was DEN. I don't know if that might be one reason, but it is a possibility.

Quoting FriendlySkies (Reply 9):
It still is, at least in Colorado.

But not Stapleton (former DEN). Stapleton Field became Stapleton International Airport, but nobody called it Denver International. DIA was only used once the new airport was built. Dulles was built decades earlier than the new Denver airport, so "DIA" was not used, officially or unofficially, by any airport in Denver at the time.

-Rampart

UA735WL · Thu Jan 15, 2015 3:32 am

Quoting IAHflyer97 (Reply 24):

Or Fresno to Cancun....

All joking aside, I've always wondered about IAH & OAD's codes.

Gasman · Thu Jan 15, 2015 8:51 am

Quoting UA735WL (Reply 27):
All joking aside, I've always wondered about IAH & OAD's codes

And Toronto? YYZ? WTF?

B747forever · Thu Jan 15, 2015 9:24 am

Quoting gdg9 (Reply 11):
This link has some possible explanation, and touches on the 200 mile issue. http://www.skygod.com/asstd/abc.html Some of this may be urban legend, but still of interest.

Now that was an interesting read.

Thanks for sharing.

mark2fly1034 · Thu Jan 15, 2015 1:10 pm

Quoting 1337Delta764 (Reply 10):
Quoting alfa164 (Reply 7):For many years, Denver International was called "DIA" publicly, even though its airport code was DEN. I don't know if that might be one reason, but it is a possibility.

A similar situation occurs in Orlando, where the local media refers to MCO as "OIA".

That drives me crazy that they call it OIA.

a380787 · Thu Jan 15, 2015 1:22 pm

Try flying Shanghai to Cincinnati to Paris all on skyteam you'll get PVG-CVG-CDG ... and that's convoluted

PA727 · Thu Jan 15, 2015 1:23 pm

Quoting jb1087xna (Reply 18):
Though I have to call it my home airport, XNA definitely falls into the characteristic of... interesting.

And here's why, at the time XNA was built, they couldn't use the desired and obvious code, NWA. XNA was chosen for three reasons: 1. It's unique, 2. It still refers to Northwest Arkansas (NA), 3. They liked the way it alluded to what they considered to be an "Exciting New Airport.

Now you kno

bond007 · Thu Jan 15, 2015 2:19 pm

Quoting 1337Delta764 (Reply 10):
A similar situation occurs in Orlando, where the local media refers to MCO as "OIA".

...and a similar situation down the road, where they refer to TPA as TIA!

propellix · Thu Jan 15, 2015 2:38 pm

Quoting tymnbalewne (Reply 13):

ATC NEVER used IATA codes; so that couldn´t be the point.
ATC always used ICAO 4-letter codes.
Actually regarding the USA, that doesn´t help it all, as for the major U. S. airports the ICAO codes differ from the IATA ones only through a K added in first position: KIAD, KJFK, KATL, KBOS, KLAX, etc.

I have to admit, I prefer the ICAO codes as they also indicate world region and country (if the first letter is not indicating country like USA/K, Canada/C, China/Z or former USSR/U).
I think the main reason for IATA codes sticking was the need to save on any possible data volume regarding the first generation of automatic distribution/processing systems.

Same reason why IATA uses 2 letter airline codes and ICAO three letter and 3 digit aircraft type codes versus 4 digit ICAO aircraft codes.

drgmobile · Thu Jan 15, 2015 2:43 pm

Quoting gdg9 (Reply 11):
I think ICAO rules prohibit airports within 200 miles of each other from having the same first two or last two letters in the code, so IAD couldn't have been DIA when created.

Not so much. More than 95% of the airport codes in Canada start with Y

727LOVER · Thu Jan 15, 2015 2:51 pm

Quoting 1337Delta764 (Reply 10):
A similar situation occurs in Orlando, where the local media refers to MCO as "OIA".

Same with TPA, referred to in local media as TIA

Quoting thomasphoto60 (Reply 17):
Sioux City has been trying for years to get their code SUX changed, with no luck.

I think the only airports in the USA that have had their codes changed were:
DIA

IAD
BAL

BWI
IDL

JFK

Quoting TWA772LR (Reply 22):
Its a good thing no airline flies Sioux City to Dickinson, ND.

or through Fresno!

IADCA · Thu Jan 15, 2015 2:52 pm

Quoting tymnbalewne (Reply 13):
Re: IAD....I seem to recall that, back in the day when ATC strips were handwritten, DIA and DCA could easily be confused

Quoting smokeybandit (Reply 19):
That's how I've understood it, too.

It's basically this, but it also has to do with reading bag tags quickly as well. People generally read words (to simplify) by looking at the beginning and end of a word, which is why typos in the mdidle of wrdos don't mkae it impssbiole to read tehm. The quicker you read, the stronger this tendency becomes. DCA and DIA would only differ by a single letter - the middle one - hence IAD.

[Edited 2015-01-15 07:51:21]

flylku · Thu Jan 15, 2015 3:13 pm

Someone who knows their history better than I do confirm or refute this but I believe that IAD originally had a different code that created confusion (I think with a Dallas airport ?) so it was changed to IAD. I will heck with my dad who will remember the details.

brilondon · Thu Jan 15, 2015 3:25 pm

Quoting gasman (Reply 28):

And Toronto? YYZ? WTF?

Rush would have to change their song if it was anything else.

Canada's airports have the Y in front of them to differentiate from the U.S. airports I believe but I am probably wrong.

26point2 · Thu Jan 15, 2015 3:59 pm

Quoting 727LOVER (Reply 36):
or through Fresno!

Plenty of airlines go through Fresno..

Quoting brilondon (Reply 39):
Canada's airports have the Y in front of them to differentiate from the U.S. airports I believe but I am probably wrong.

Actually, Canada's airport codes all start with a C to differentiate them from the rest.

cathay747 · Thu Jan 15, 2015 4:07 pm

As far as I know, they stand for (and always did) "International Airport Houston" and
"International Airport Dulles". Plain and simple. As to the reasoning, well, that's anybody's
guess.

slider · Thu Jan 15, 2015 4:11 pm

Quoting Burchfiel (Reply 12):
I had no idea that new codes can't start with N, K, or W.

Yup- that's why we have BNA, EWR, etc and explains those codes.

Quoting 727LOVER (Reply 36):
DIA IAD
BAL BWI
IDL JFK

I believe you're right. Idlewild used to be a golf course (or the land was supposed to become one, can't recall offhand) and then it became the airport, to be changed in 1963 right after JFK was assassinated.

****

As it pertains to IAH, however, all commercial traffic shifted from HOU once IAH opened. Because of the risk of aviator and navigatory confusion, they had to have a brand new second code and HOU simply couldn't shift north. HOU stayed GA only until Southwest started up.

D L X · Thu Jan 15, 2015 4:12 pm

Quoting 26point2 (Reply 40):
Actually, Canada's airport codes all start with a C to differentiate them from the rest.

And most (nearly all) American airport codes start with K, we just drop the K. The K is a radio station identifier for the airport. The United States uses radio stations that begin with the letters W-, K-, N- and P-.* (So, it's actually KEYW, which makes a lot of sense, don't it?)

My question has always been, knowing that it's actually KEWR and KORF and not NEWR and NORF, why do we drop the N from Newark and Norfolk? Why not NEW or NWK and NRF or something like that? I'm sure there are others as well, just those two pop to the front of my mind.

* Someone correct me if this isn't 100% correct.

[Edited 2015-01-15 08:19:02]

lugie · Thu Jan 15, 2015 4:20 pm

Quoting D L X (Reply 43):
My question has always been, knowing that it's actually KEWR and KORF and not NEWR and NORF, why do we drop the N from Newark and Norfolk? Why not NEW or NWK and NRF or something like that? I'm sure there are others as well, just those two pop to the front of my mind.

three-letter IATA codes starting with N are reserved for Air Force Bases in the US as far as I know, so to avoid confusion there are no civilian airports with Nxx codes in North America, however we do have them in Europe ( NUE, NCL for instance)

superjeff · Thu Jan 15, 2015 4:23 pm

Quoting flylku (Reply 38):
Someone who knows their history better than I do confirm or refute this but I believe that IAD originally had a different code that created confusion (I think with a Dallas airport ?) so it was changed to IAD. I will heck with my dad who will remember the details.

DAL is Dallas Love Field (DAL=Dallas); DUL could have been Dulles, but has pretty negative connotations (although this would possibly have been fitting for that airport, at least in the old days

a380787 · Thu Jan 15, 2015 4:32 pm

Quoting Slider (Reply 42):

I believe you're right. Idlewild used to be a golf course (or the land was supposed to become one, can't recall offhand) and then it became the airport, to be changed in 1963 right after JFK was assassinated.

Funny it still feels like a golf course because the new JFK T4B for Delta is as long as multiple par-5 holes.

psolk · Thu Jan 15, 2015 4:40 pm

ORD and MCO always got me...

YYCSpotter · Thu Jan 15, 2015 4:59 pm

Quoting 26point2 (Reply 40):
Actually, Canada's airport codes all start with a C to differentiate them from the rest.

If we look at the airport code for Toronto, CYYZ, there are three parts

"C" = Canadian Airport

"Y" = Weather services available

"YZ" = Airport Identifier.

I hope this clears things up for Canadian Airports!

bmacleod · Thu Jan 15, 2015 5:00 pm

IAD as the International Airport for DC compared to DCA which flies domestic and to Canada.

IAH as the International Airport for Houston compared to HOU.

[Edited 2015-01-15 09:02:42]

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