Newbie question


#1

I was listening to BOS approach and JBLU 490 was asking about a CAT2 or CAT3 apporach for ILS 4R, I was wondering if anyone knows the difference between a CAT2 or CAT3 or even what a CAT approach is? I’m only 20 and I’ve been an enthusiast for commerical aircraft since I was a very young kid but this is new to me since I haven’t kept up since I was about 15 or so. Thanks for the help if you know the answer, I’m just starting to get back into this stuff…


#2

From FAA Glossary

ILS-

(See INSTRUMENT LANDING SYSTEM.)

ILS CATEGORIES-

  1. ILS Category I. An ILS approach procedure which provides for approach to a height above touchdown of not less than 200 feet and with runway visual range of not less than 1,800 feet.-

  2. ILS Category II. An ILS approach procedure which provides for approach to a height above touchdown of not less than 100 feet and with runway visual range of not less than 1,200 feet.-

  3. ILS Category III:

a. IIIA.-An ILS approach procedure which provides for approach without a decision height minimum and with runway visual range of not less than 700 feet.

b. IIIB.-An ILS approach procedure which provides for approach without a decision height minimum and with runway visual range of not less than 150 feet.

c. IIIC.-An ILS approach procedure which provides for approach without a decision height minimum and without runway visual range minimum.

ILS PRM APPROACH- An instrument landing system (ILS) approach conducted to parallel runways whose extended centerlines are separated by less than 4,300 feet and the parallel runways have a Precision Runway Monitoring (PRM) system that permits simultaneous independent ILS approaches.


Note that when the approach supports it and the aircraft is suitable equipped, you can land on the runway before you see it under a CAT IIIC approach.

Look HERE for the terminal procedures available at Logan. Look for the runway in use and the CAT level of the approach. Have fun!


#3

Good answer!

To give a short version: The ILS that most pilots fly is a CATegory 1, but that phrase is normally ommitted. CAT 2 & 3 are approaches that allow lower minimums (see details in jreeves’ post). They require special aircraft and flightcrew certification.


#4

Right on, thanks guys. I knew what an ILS approach is I just wasn’t aware of the “CAT” differences, great answer tho, appreciate it.


#5

ILS= Intsrument Landing Sytem, right?

what is the dif btw IFR and VFR?:lol:


#6

IFR = Instrument Flight Rules. Your instruments are your navigational best friends.

VFR = Visual Flight Rules. Your own eyes are all the help you’re going to get.


#7

ok, thank you