Moderators: richierich, ua900, PanAm_DC10, hOMSaR

Topic Author
Posts: 402
Joined: Sat Jun 24, 2006 3:59 am

Does Anyone Know ILS Category 1B?

Thu Jan 08, 2015 1:36 pm

This NOTAM has been posted for RDG (Reading, PA) for a little while now:

!RDG 08/004 RDG NAV ILS RWY 36 CHANGED TO CAT 1B 1408131715-PERM

Can anyone out there find or provide a definition for Cat 1B? So far, all of us are stumped here where I work at the airport what the actual change is (it was just a standard Cat 1 ILS previously).
Posts: 3086
Joined: Sun Jan 07, 2001 4:42 am

RE: Does Anyone Know ILS Category 1B?

Thu Jan 08, 2015 2:25 pm

Never heard of CAT1B. Maybe this is about SA CAT 1 which might be available on the runway.

With an SA (special authorization) CAT 1, you can basically land with a lower DH and RVR value on a CAT 1 apprch, down to a DH of 150ft and RVR 1400ft, if you meet the OPS SPEC requirements.

Checked on, and no such plates for Reading so far. Still showing the ones that expired at 0900Z this morning. They should update with the new ones any day now.

It is only CATIII approaches that are subdivided into CATIIIa, b or c. CAT I and II approaches don't have that.

[Edited 2015-01-08 06:30:26]
us Air Traffic Controllers have a good record, we haven't left one up there yet !!
Posts: 3226
Joined: Fri Dec 03, 1999 2:47 am

RE: Does Anyone Know ILS Category 1B?

Thu Jan 08, 2015 2:32 pm

Hopefully it got them better minimums.... right now the ILS has minimums at that of a GPS approach....

Typically an ILS has minimums of 1/2 mile visibility and 200 ft ceilings.

I may be a little off on these but here is a rough breakdown of the types of ILS's

CAT-I 200 ft and 1/2 mile
CAT-I Enhanced 200 ft and 1800-2400 ft RVR
CAT-II 100 ft and 1200 RVR
CAT-IIIa/b/c - 600/700 ft RVR
Experience is what you get when what you thought would work out didn't!
Posts: 266
Joined: Thu Jul 15, 2004 9:18 pm

RE: Does Anyone Know ILS Category 1B?

Thu Jan 08, 2015 4:15 pm

Look here:

And a list of US airports with it's performance classification's:

In the end nothing a pilot has to worry about.



[Edited 2015-01-08 08:20:52]
Posts: 266
Joined: Thu Jul 15, 2004 9:18 pm

RE: Does Anyone Know ILS Category 1B?

Thu Jan 08, 2015 7:02 pm

Here is a nice document from the ICAO:

Check out appendix C:


The ILS facility classification system provides a more comprehensive method of describing ILS performance than the simple CAT I/II/III classification. An example of an ILS facility classification is “III/E/4”. ILS facility classification is described in Annex 10, Volume 1.

In short: ILS CAT 1b is a facility classification.

Have fun,


Who is online

Users browsing this forum: musapapaya and 36 guests

Popular Searches On

Top Photos of Last:   24 Hours  •  48 Hours  •  7 Days  •  30 Days  •  180 Days  •  365 Days  •  All Time

Military Aircraft Every type from fighters to helicopters from air forces around the globe

Classic Airliners Props and jets from the good old days

Flight Decks Views from inside the cockpit

Aircraft Cabins Passenger cabin shots showing seat arrangements as well as cargo aircraft interior

Cargo Aircraft Pictures of great freighter aircraft

Government Aircraft Aircraft flying government officials

Helicopters Our large helicopter section. Both military and civil versions

Blimps / Airships Everything from the Goodyear blimp to the Zeppelin

Night Photos Beautiful shots taken while the sun is below the horizon

Accidents Accident, incident and crash related photos

Air to Air Photos taken by airborne photographers of airborne aircraft

Special Paint Schemes Aircraft painted in beautiful and original liveries

Airport Overviews Airport overviews from the air or ground

Tails and Winglets Tail and Winglet closeups with beautiful airline logos