Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
Approach CAT I, II, III  
User currently offlineMhsieh From United States of America, joined Jul 2000, 332 posts, RR: 0
Posted (15 years 1 month 3 weeks 5 days 18 hours ago) and read 18800 times:

Can anyone explain the definition of the Cat I, II and III approach and which airliners are equiped for the different categories?

6 replies: All unread, jump to last
User currently offlineIainhol From , joined Dec 1969, posts, RR:
Reply 1, posted (15 years 1 month 3 weeks 5 days 17 hours ago) and read 18746 times:

The differences are how bad this vis can be. Cat IIIc is your wheels touch as you see the runway!

User currently offlineFLY 8 From Austria, joined Dec 2000, 329 posts, RR: 0
Reply 2, posted (15 years 1 month 3 weeks 5 days 14 hours ago) and read 18752 times:

CatI means:
That´s what you can fly when you have the Instrument rating: Your minimum is 550m RVR (Runway visulal range) and a descision hight of 200 feet above ground.

CATII means.
You need a special training and a special aircraft.
The aircraft has to have two different flight guidance systems, one autopilot, at least one operative radar altimeter. And some other small things. The approach has to be made with the autopilot. In our company and in many or almost all we have a procedure what is called "monitored approach" That means, the copilot is flying the airplane to the minimum Actually he only monitors the airplane, cause the autopilot is flying. In his mind the copilot is not landing, he always things on the mist approach procedure. And when reaching the minimum the pilot calls minimum and when the captain doesn´t say anything or when he say´s go around, the copilot is initiating the missed approach procedure.
The captain is looking outside all the time during the approach so that his eyes get used to the light . And the copilot looks inside to fly.
The minimum for a CATII approach is 350m RVR and 100 feet decision height.
At minimum when the captain has the approach lights in sight he calls "my controls" and lands the airplane. The copilot stays with his eyes on the Instruments and calls out any deviations.

CATIII means:
There are CATIII a, b and c approaches! CATIIIa means that the airplane has to have the equipment wich I have described for CATII plus a autothrottle system and an auto landing system.
The minimum is 200m RVR and 50 feet dh.
CATIIIb is the same as CATII and CATIIIa plus automatic stopping system, that means that the airplane controlles itself down to taxi speed. The minimum is 100m RVR and 0 feet dh. Thats the lowest minimum wich is allowed. CATIIIc would be possible, but it´s not allowed. The requirement for CATIIIc is the same as for the others plus automatic taxiing and automatic dogging on the gate. The minimum for this would be 0 m RVR and 0 feet dh. This category of approach is not allowed because with 0 meter RVR you the rescue troup couldn´t see anything in case something would happen.
I could give your more details about anything for example: The 777 is certiefied for CATIIIb approaches in single engine operation. I could give you a lot of detailes about certiefication requierments and other thing but that´s to much work because my AWO manual (All Weather Operation manual) has a few hundret pages.

But if you are interrested in somethin just let me know!


yes i can handle that alone. - - -famous last words
User currently offlineMhsieh From United States of America, joined Jul 2000, 332 posts, RR: 0
Reply 3, posted (15 years 1 month 3 weeks 5 days 2 hours ago) and read 18683 times:

Thank you very much for that detailed explanation. What kind of airplane do you fly, Benjamin?
Hope you can help me with many other questions I have.

User currently offlineDc10hound From United States of America, joined Dec 2000, 463 posts, RR: 5
Reply 4, posted (15 years 1 month 3 weeks 3 days 13 hours ago) and read 18651 times:

>>CATIIIc is the same as for the others plus automatic taxiing and automatic dogging on the gate. <<

I've never heard of "automatic" taxiing. How is this function performed? Also the term "dogging" (although I've called penty of A/C dogs) is unfamiliar to me. explain, please. (I'm just a dumb Yank)

"Eagles soar. But weasels never get sucked into jet intakes.."
User currently offlineFLY 8 From Austria, joined Dec 2000, 329 posts, RR: 0
Reply 5, posted (15 years 1 month 3 weeks 1 day 6 hours ago) and read 18636 times:


The function automatic taxiing is not availlable, since there are no CATIIIc approaches allowed. Just imagine could you taxi an aircraft where the cockpit is 9 meters above the ground in 0 meters visibility. In that case you would need an aircraft wich can taxi automatically.

Dogging doesn´t exists it´s called docking. Sorry my fault. I think you know what is meant by it.

If you have any questions, just ask me!


yes i can handle that alone. - - -famous last words
User currently offlineRayChuang From United States of America, joined Jun 2000, 8291 posts, RR: 4
Reply 6, posted (15 years 1 month 2 weeks 4 days 11 hours ago) and read 18602 times:

Speaking of CAT IIIb landings, I've heard that NASA recently modified one of their planes with special differential GPS receivers and found out they could literally land a plane with GPS guidance with an amazing accuracy of within 3 meters of centerline! And that is without ILS/MLS glide-slope transponders, too.

3 meters (around 10 feet) accuracy means you can land a plane anywhere in the world even in the worst low visibility conditions. No wonder even the US Navy is sponsoring research into using GPS for more accurate carrier landings.

Top Of Page
Forum Index

Reply To This Topic Approach CAT I, II, III
No username? Sign up now!

Forgot Password? Be reminded.
Remember me on this computer (uses cookies)
  • Tech/Ops related posts only!
  • Not Tech/Ops related? Use the other forums
  • No adverts of any kind. This includes web pages.
  • No hostile language or criticizing of others.
  • Do not post copyright protected material.
  • Use relevant and describing topics.
  • Check if your post already been discussed.
  • Check your spelling!
Add Images Add SmiliesPosting Help

Please check your spelling (press "Check Spelling" above)

Similar topics:More similar topics...
CAT I,II,III Approaches! posted Wed Sep 1 2004 21:56:30 by BMI701EGCC
A Newbie In Need: CAT I/II/III... posted Sun Jun 6 2004 01:55:28 by Futterman
Differences Among CAT I/II/III Approaches? posted Thu Apr 3 2003 03:56:23 by FSPilot747
Ceiling And RVR For CAT I, II, III posted Thu Jul 26 2001 23:23:20 by Modesto2
CAT I,II,III posted Thu Mar 29 2001 00:42:38 by H. Simpson
Is The Standard MD80 CAT II Or CAT III ( A / B ) posted Mon Feb 28 2005 21:51:31 by PW2040
CAT II And CAT III posted Mon Jun 23 2003 22:33:22 by Mb339
CAT -I, II, Or III Approaches posted Sat Jul 28 2001 09:33:41 by UA752
CAT I, CAT II, Can Someone Explain? posted Fri Feb 18 2005 04:50:30 by EZEIZA
Cat II ILS? posted Wed Mar 17 2004 00:40:08 by Mu2

Sponsor Message:
Printer friendly format