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Squawk Codes  
User currently offlineJhooper From United States of America, joined Dec 2001, 6204 posts, RR: 12
Posted (11 years 6 months 1 week 1 day 18 hours ago) and read 3979 times:

Is there a system that ATC uses to assign transponder codes, or is it pretty much random? I've noticed that if I'm flying VFR into class D airspace, sometimes I'll get a code like 0432 (usually starts with a zero), whereas if I'm IFR I'll get a code like 4331 (usually starts with a 4).


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11 replies: All unread, jump to last
 
User currently offlineShaun3000 From United States of America, joined Mar 2002, 445 posts, RR: 0
Reply 1, posted (11 years 6 months 1 week 1 day 18 hours ago) and read 3964 times:

I can tell you that they are sequential. I've called up ATC, before, and been assigned a code. Then other people have called up and each given a code one higher than mine.

User currently offlineKAUSpilot From United States of America, joined Jan 2002, 1958 posts, RR: 33
Reply 2, posted (11 years 6 months 1 week 1 day 17 hours ago) and read 3935 times:

I've also noticed than when you go VFR into class B-D they'll usually give you a code starting with a zero.

User currently offlineMinuteman From United States of America, joined Aug 2000, 271 posts, RR: 0
Reply 3, posted (11 years 6 months 1 week 1 day 16 hours ago) and read 3919 times:

The answer to your question can be found in FAA Order 7110.65 "Air Traffic Control", section 5-2 "Beacon Systems"

http://www2.faa.gov/atpubs/ATC/Chp5/atc0502.html

To list a few highlights (remember each digit is only a three-bit Binary Coded Decimal, so its range is 0-7):

1200 is VFR traffic
2100-2500 for flights in Class A airspace (only 197 discrete codes at any given time?)
4000 series are flights requiring frequent course/altitude changes (test flights)
4400 series is reserved for pressure suit flights

Anyone know what the "FAKER" flights mentioned in 5-2-11 are? Sounds like one of those words you'd learn about in bad times ... like "SCATANA"

Minuteman


User currently offlineBackfire From Germany, joined Oct 2006, 0 posts, RR: 0
Reply 4, posted (11 years 6 months 5 days ago) and read 3717 times:

Minuteman:

A 'faker flight' is a military term for a friendly strike aircraft which is pretending to be a hostile aircraft for the purpose of air defence exercises. It's faking the role - hence the name.

Hope that answers your question.

Backfire

[Edited 2003-02-21 22:12:58]

User currently offlineJhooper From United States of America, joined Dec 2001, 6204 posts, RR: 12
Reply 5, posted (11 years 6 months 4 days 23 hours ago) and read 3723 times:

Thanks for that link Minuteman.


Last year 1,944 New Yorkers saw something and said something.
User currently offlineTimz From United States of America, joined Sep 1999, 6816 posts, RR: 7
Reply 6, posted (11 years 6 months 4 days 22 hours ago) and read 3701 times:

Still scratching my head over that link. The typical IFR flight will get a code before takeoff and retain it for the whole flight, won't it?

Codes 2100 thru 2500 would be 257 codes, not 197?


User currently offlineBackfire From Germany, joined Oct 2006, 0 posts, RR: 0
Reply 7, posted (11 years 6 months 4 days 22 hours ago) and read 3709 times:

Codes 2100 thru 2500 would be 257 codes

Yes.

2100 to 2500 = 401 codes (octal)

= (4 x 64) + (0 x 8) + (1 x 1) (decimal)

= 256 + 0 + 1

= 257 total





User currently offlineOE-LDA From , joined Dec 1969, posts, RR:
Reply 8, posted (11 years 6 months 4 days 8 hours ago) and read 3679 times:

As far as I know it is so that every ATC station has a set of transponder codes (e.g. Wien Tower (LOWW) has 0001 - 0012 or 0016, I am not sure) which they assign one after the other. But if you are handed over, let's say on a VFR flight from Wien Tower to Wien Information, you will receive a new transponder code, otherwise Wien Tower will run out of codes. Some airports have fixed codes (like LOAV departure is 1521). Then there are the general codes: 7000 for VFR, 7500 for hijack, 7600 for radio failure, 7700 for emergency.

Regards, OE-LDA


User currently offlineZID From United States of America, joined Jan 2002, 294 posts, RR: 4
Reply 9, posted (11 years 6 months 2 days 22 hours ago) and read 3592 times:

Each facility has it's own set of codes assigned for it's use. I can't remember exactly what the code range is for a flight that originates with Indy Center, but it includes the 6600's. At least twice a day I have to get a new code for a departure because the computer assigned a 666 code, and I just don't like issuing those codes.


I'm not joking! This is my job!
User currently offlineContact_tower From Norway, joined Sep 2001, 536 posts, RR: 1
Reply 10, posted (11 years 6 months 2 days 21 hours ago) and read 3600 times:

It is not a sipmple aswer to this question:

Most towers have a small "bank" of codes available for use in their airspace, or in a area not to far away. Additionally each Approach or Area Centre have a bank for flights in their area, if the area is large, some codes may not be permittet used in certain areas.

IFR flights generally keep their code trough out their flight, and it's picked from the Area code bank, but it the flight is long, a change of code might be in order. (Ex: the plane get a new code when crossing a certain FIR border or whatever)
The use of the code "banks" are a bit different from place to place.
Certain parts of the allotted bank might be for the specific FIR only, while another part of the bank is permitted used outside the FIR.

Example:

If I have a flight that depart my airfield for a short IFR or VFR flight to one of 4 neighbouring airports I can assign a squawk from our local bank.

If I have a flight departing to ENGM, wich is outside the scope of our codebank, I get a squawk from the Bodo Controll Centre.
They pick a squawk from a "outside FIR, inside country" code bank.

If the flight has ESSA as destination (not in FIR or country), they pic a code from a different bank.

That said, the code bank might be in a computersystem, or just a list on a pice of paper.

Our system will get a upgrade this spring, and ALL squawks for Norway will be assigned from a automatic central code bank, picking codes according to flight plan route.


Anders
ATCO
ENDU TWR/Approach


User currently offlineJhooper From United States of America, joined Dec 2001, 6204 posts, RR: 12
Reply 11, posted (11 years 6 months 2 days 19 hours ago) and read 3719 times:

At least twice a day I have to get a new code for a departure because the computer assigned a 666 code, and I just don't like issuing those codes.

Good, I hope I talk to you next time I pass thru Indy center; I wouldn't want a code like 666.



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