Here's the rules for creating US aircraft registrations. I know this isn't
directly related to airline flight numbers but it does make for interesting
reading. The letters "I" and "O" are not allowed in registrations. What is
interesting is that I didn't realize the aircraft category and the dash are
still legal to use in registrations, albeit they are mostly omitted).
I got this from the landings.com web page - they also have the rules there
for German registrations.
Registration Rules
These rules were written up by Andreas Gehrs-Pahl, schnars@ais.org.
US Registration numbers: Rules (see FAR 47.15(b)): The rules for
registration numbers of aircraft in the USA are:
Description:
Form: N[c][-]n[n][n][X][X]
see : 1 2 3 4 5 6 7 8
N (international prefix: USA)
C/L/R/X (Category, mostly omitted)
- (dash, mostly omitted)
digit (1 to 9)
digit (0 to 9 or nothing)
digit (0 to 9 or nothing)
character (0 to 9, A to H, J - N, P - Z or nothing)
character (0 to 9, A to H, J - N, P - Z or nothing)
min.: N1
max.: NX-999ZZ
1) International Prefix:
N (for USA)
2) Category:
Not part of the Registration nor the Prefix, but is sometimes displayed on
the aircraft (especially before 1950s):
C = Standard,
L = Limited,
R = Restricted,
X = eXperimental.
3) Separator:
The dash (-) or a space ( ) as a Seperator between Prefix and Registration
is in most cases omitted.
4-8) Registration:
1 to 5 characters, allowed are digits (0 - 9) and letters (A - H, J - N, P -
Z), exempt are I and O, to not be confused with the digits 1 or 0. The
registration can be split into two categories:
numeric: 1 to 5 digits (N1 to N99999)
alphanumeric: (here I have to use examples to be 100% clear):
1A - 9999A (9999 registrations)
...
1Z - 9999Z (for all 24 allowed characters)
and
1AA - 999AA (999 registrations)
...
1ZZ - 999ZZ (for all 24*24 allowed combinations)
Summary: N plus 1 to 5 characters (usually without a dash '-', sometimes
with a category letter; first character is always a digit from 1 to 9; can
be followed by up to 4 more digits and can end with up to 2 letters, but
letters can not be followed by digits; the characters I and O are not
allowed; no other rules exist, concerning:
military/government ownership,
special purpose/prototype/evaluation,
aircraft type, or
location.
Remarks: A total of 99,999 + 9999 * 24 + 999 * 24 * 24 = 915,399 aircraft
could be registered at any given time. (The 1990/91 FAA database contains
about 300,000 registrations). NASA owned aircraft have mostly registrations
of the form NxxxNA, were xxx is a number from 1 to 999. This is not a rule,
and this is not a NASA specific registration form. Government owned special
purpose aircraft (like CIA operated U-2s) sometimes use 'fake'
registrations, which are not in the register, or fly without any
registrations. Without a civil registration, it is difficult to get
overflight or landing rights from any other country.
----- Original Message -----
From: "Matthew Montano" <mmontano@direct.ca>
To: <AIRLINE@LISTSERV.CUNY.EDU>
Sent: Sunday, January 27, 2002 10:23
Subject: Re: [AIRLINE] United's flight number scheme (was Re: AC's 3xxx
flight #s)
Another curious question, though I have no direct evidence of it myself. Are
there any flight numbers that due to linguistic reasons are not used? For
example manufacturers of products with serial numbers with either use 1's or
I's, but never both (same goes with O's and 0's.)
Matthew
-----Original Message-----
From: The Airline List [mailto:AIRLINE@LISTSERV.CUNY.EDU] On Behalf Of
Michael C. Berch
Sent: January 25, 2002 12:31 PM
To: AIRLINE@LISTSERV.CUNY.EDU
Subject: United's flight number scheme (was Re: AC's 3xxx flight #s)
As of a year or two ago, United's scheme was approximately this:
UA1-UA2 Round-the-world flights (gone now?)
UA3-UA799 General domestic and Canada
flights
UA800-899 Pacific flights (incl. US
continuation segments)
UA900-999 Atlantic flights (incl. US
continuation segments)
UA1000-1999 General domestic and Canada flights
UA2000-2999 Shuttle by United (gone now)
UA3000-3999 Code shares on other carriers
UA4000-6999 United Express (operated by
contractors)
UA7000-7999 Unused? Charters? Cargo?
UA8000-8999 Reserved for ATC renumbering*
UA9000-9999 Special flights - charters, extra
"passenger
protection" sections,
delivery and
repositioning flights, etc.
Normally even numbers are eastbound, odd are westbound.
* When flights with a similar or the same number would overlap in an ATC
sector, one of the flights is renumbered, usually flight number +
8000. For example, let's say UA921 operates LHR-ORD-LAX (with a change
of equipment in ORD). If the inbound from London is seriously delayed, UA
may dispatch the domestic continuation (most of whose pax have no idea
"their" flight is delayed inbound, since there's an empty 767 sitting there
at the gate), and the inbound LHR-LAX pax will be
accommodated on other flights. The domestic leg will be redesignated
UA8921 for ATC purposes so it does not get confused with the "real" UA921
coming in from LHR.
These schemes have been upset by the termination of Shuttle by United; it
would be nice to know UA's current scheme, although I'm sure it is somewhat
similar.
--
Michael C. Berch
mcb@postmodern.com