Sponsor Message:
Aviation Technical / Operations Forum
My Starred Topics | Profile | New Topic | Forum Index | Help | Search 
ILS Landing System  
User currently offlineYYZatcboy From Canada, joined Apr 2005, 1090 posts, RR: 0
Posted (9 years 7 months 1 week 2 days 22 hours ago) and read 4098 times:
AIRLINERS.NET CREW
CUSTOMER SERVICE & SUPPORT

Hey everyone
I was just wondering if anyone could let me know what exactly a cat 1,2,3 ILS means.
Thanks


DHC1/3/4 MD11/88 L1011 A319/20/21/30 B727 735/6/7/8/9 762/3 E175/90 CRJ/700/705 CC150. J/S DH8D 736/7/8
12 replies: All unread, jump to last
 
User currently offlineCO737 From United States of America, joined Dec 2000, 143 posts, RR: 0
Reply 1, posted (9 years 7 months 1 week 2 days 22 hours ago) and read 4044 times:

Catergories refer to the minimums for the ILS. CAT I are your standard minimums (200 ft. AGL and 1 mile visibility). CAT II have lower minimums (100 and 1/2, I believe). CAT III don't have a ceiling requirement, but are based on the runway visual range. Any instrument rated pilot can shoot a CAT I, but CAT II and III approaches require special training and aircraft equipment.


Every takeoff is optional, but every landing is mandatory.
User currently onlineStarlionblue From Greenland, joined Feb 2004, 17111 posts, RR: 66
Reply 2, posted (9 years 7 months 1 week 2 days 19 hours ago) and read 3944 times:

Here's some more data stolen from old posts.

Aviation - ILS Categories

xxx
Cat.I - 200 feet DH - 2,400 feet (or 1,800 feet) RVR
Metric: 800 metres of 550 meters RVR...
xxx
Cat II Restricted - 150 feet DH - 1,600 feet RVR
metric: 500 metres RVR
xxx
Cat II - 100 feet DH - 1,200 feet RVR
Metric: 350 metres RVR
xxx
Cat.IIIa - 700 feet RVR - no DH (alert height generally 50 feet)
Metric: 250 meters RVR
xxx
Cat.IIIb - 600 feet RVR - no DH (alert height generally 35 feet)
Metric: 175 metres RVR
xxx
Cat.IIIc - zero ceiling, zero visibility - "blind" landing...

RVR is Runway Visual Range, basically a distance in feet that the pilot can expect to see forward in his airplane.


The ILS equipment at the airport must be certified for it, as well as aircraft type (actually individual aircraft) and crew have to be certified.


Alert Height (AH) is not like a Decision Height (DH) -
At "DH" (obtained from radio altimeter for Cat.II) you have to make a DECISION to land or go-around...
xxx
In Cat.III operations, there is no DH... but you have to make a decision to land based on "what you see"... pilots find the DH "decision" very convenient for Cat.II, but did not exist for Cat.III...
xxx
So in "pratical operations", the AH is used somewhat like a DH, but is not regulatory. In other terms, we expect to "see the runway" at that point... which is about 50 feet radio altimeter, just about where the runway threshold is located, in Cat.IIIa minimums. In Cat.IIIb, happens at about 35 feet...
xxx
Many 747 are equipped for Cat.IIIa operations (not Cat.IIIb), although most of the "Classic" 747s (with 3 autopilot channels) have the LRCU that is required for Cat.IIIb... LRCU = landing roll control unit... keeps the nose wheel on the center line, using the localizer...



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 3, posted (9 years 7 months 1 week 2 days 19 hours ago) and read 3943 times:

Quoting Starlionblue (Reply 2):
Many 747 are equipped for Cat.IIIa operations (not Cat.IIIb), although most of the "Classic" 747s (with 3 autopilot channels) have the LRCU that is required for Cat.IIIb... LRCU = landing roll control unit... keeps the nose wheel on the center line, using the localizer.

All the -400s come from Boeing with the capability for CAT IIIC. The operator's ops specs might not be for CATIIIC but for a lower category. That lower category would then become limiting factor.

For example at SQ, we are CATIIIB with an alert height of 20'.


User currently offlineBoeing7E7 From , joined Dec 1969, posts, RR:
Reply 4, posted (9 years 7 months 1 week 2 days 19 hours ago) and read 3932 times:

CAT I/II - ILS, Terrain, Aircraft Equipment, Approach Lights and Crew based minima.

CAT II is nothing more than a CAT II with additional pilot qualifications.

Explaining TERPS is a real pain in that I can't send you to a direct document as the FAA has seen fit not to make all of the publications available to the general public. If you ask a FSDO they may provide you with a copy of the TERPS manual the FAA uses to define approach minima, slopes and system criteria.

There are about 8 components that make up the TERPS standard which enables the Category of ILS approach. For example. CAT I/II only requires ALSF-I approach lights, CAT II/III is ALSF-2. A simple variation in the airfield altitude changes the dynamics of the approach surface exponentially.

Here's a link where you can get some very basic info on TERPS. The basic document is the 8260, but it's not all there. It's as if they don't want some farmer with a landing strip is goign to go out and trying to get his own CAT III approach or something:

Basic TERPS 8260.3B(Sections not included):

http://av-info.faa.gov/terps/directives%20page.htm


Very Very Basic CAT II/III TERPS:

http://av-info.faa.gov/terps/Policies1/TIL00005Aatt.PDF


User currently offlineMD11Engineer From Germany, joined Oct 2003, 14127 posts, RR: 62
Reply 5, posted (9 years 7 months 1 week 2 days 19 hours ago) and read 3925 times:

Quoting Starlionblue (Reply 2):
Here's some more data stolen from old posts.

Looks like 747Skipper!  Wink

Jan


User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 6, posted (9 years 7 months 1 week 2 days 16 hours ago) and read 3879 times:

Has any FAA official seen my signature yet? 
The problem with the CATIIIC system is that you might find the runway blindfolded, but will you find the gate? Big grin

[Edited 2005-04-22 05:18:22]

User currently offlineHAWK21M From India, joined Jan 2001, 31702 posts, RR: 56
Reply 7, posted (9 years 7 months 1 week 2 days 14 hours ago) and read 3852 times:

Quoting MD11Engineer (Reply 5):
Looks like 747Skipper!

Too bad Hes not gettng back.
regds
MEL



Think of the brighter side!
User currently offlineBoeing7E7 From , joined Dec 1969, posts, RR:
Reply 8, posted (9 years 7 months 1 week 2 days 5 hours ago) and read 3784 times:

Quoting FLY2HMO (Reply 6):
The problem with the CATIIIC system is that you might find the runway blindfolded, but will you find the gate?

It does exist. It's called MITL, SMGCS and RWSL.

Might want to change your signature.


User currently offlineBoeing7E7 From , joined Dec 1969, posts, RR:
Reply 9, posted (9 years 7 months 1 week 2 days 3 hours ago) and read 3766 times:

I should also add that the US just shit canned another landing system LAAS for the short term. After wasting 7 years with Raytheon and 2 years with Honeywell they magically discovered that LAAS as envisioned would not provide CAT III capability. Nice. Real nice. MLS anyone???? AGAIN!!!!!!!!!!!

Although with MMR's, FMS, WAAS, IRS/INS and MLS accuracy.... Imagine the possibilities.... Hello FAA... Anyone listening?????


User currently offlineGlom From United Kingdom, joined Apr 2005, 2821 posts, RR: 10
Reply 10, posted (9 years 7 months 1 week 2 days 1 hour ago) and read 3728 times:

Is it the case that in a CAT IIIc approach, autoland must be used, or could a suitably skilled pilot hand fly such an approach?

User currently offlineSaab2000 From Switzerland, joined Jun 2001, 1618 posts, RR: 11
Reply 11, posted (9 years 7 months 1 week 1 day 23 hours ago) and read 3704 times:

When I flew Saab 2000s in Europe, we were certified to CAT IIIa minimas. It was handflown with a HUD - Head Up Display. If the flying pilot (always the captain in the case of the Saab 2000) deviated enough, it caused a "Loss of Approach" warning and a go-around was required.

It was a fairly simple operation to be honest, and we never had to go around.

I cannot speak of other categories of approaches, but the CAT IIIa approaches on the Saab2000 are hand flown.



smrtrthnu
User currently offlineBoeing7E7 From , joined Dec 1969, posts, RR:
Reply 12, posted (9 years 7 months 1 week 1 day 23 hours ago) and read 3711 times:

Quoting Glom (Reply 10):
Is it the case that in a CAT IIIc approach, autoland must be used,

Yes. Enhanced Vision (FLIR) may change that.


Top Of Page
Forum Index

Reply To This Topic ILS Landing System
Username:
No username? Sign up now!
Password: 


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!
  • DETAILED RULES
Add Images Add SmiliesPosting Help

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


Similar topics:More similar topics...
Inventor Patents New Emergancy Landing System posted Wed Jun 21 2006 10:54:56 by Pilot3033
What Is GLS? Global Positioning Landing System posted Fri May 13 2005 04:01:56 by Squirrel83
ILS Inventory System Question posted Thu Feb 5 2004 15:29:41 by UAL Bagsmasher
GPS Landing System: When? posted Fri Nov 23 2001 14:11:08 by Captjetblast
Question On The ILS System posted Fri May 19 2006 03:16:48 by LTU932
Do Landing Gears Have Any Anti-Lock System posted Sun Jan 13 2002 06:46:04 by Indianguy
UPS 757 Landing At Night W/o Lights? posted Thu Nov 16 2006 08:00:51 by Motopolitico
CDG Landing Fees posted Mon Nov 13 2006 18:30:05 by Jetline
VOR/ILS posted Wed Nov 8 2006 08:47:11 by Zvocio79
Boeing 737 Minimum Take-off/Landing Requirements posted Fri Nov 3 2006 16:22:57 by NZ8800

Sponsor Message:
Printer friendly format