ILS CAT I – CAT II – CAT III APPROACHES DIFFERENCES (FAA-H-8083-16B)

ILS CAT I is all well known for the GA pilot. Its DH does not go below 200 feet above TDZE, and requires a minimum visibility of no less than 800 meters or an RVR of 550 meters, depending on the case, which can be taken from instruments either at the TDZ or a midfield position, which is not allowed for CAT II or III operations.

Now, the GA pilot is normally not used to the CAT II and III operations, mainly because the requirements for these are more complex and cost restrictive. So from now on, we will look at it as commercial pilots. 

A good thing to know for the professional commercial pilot is that these minimums and requirements for the ILS CAT II and III are not the same for all operators, the authority will assign minimums and requirements for each one operator individually, although they might be setup by a guideline. Thus the importance of rechecking your company’s CAT II and III policies. Adding to this, is a must to know where your company is authorized to perform such approaches, since you might not be approved to fly an approach to certain airports. 

CAT II and III require special equipment to be installed in the ground facilities and in the aircraft, as well as special training is required for flight crews. Again, requirements depending on each company, ground equipment availability and aircraft system configuration. 

But how about those CAT III a – b – c sub-indexes? Well, they are just more restrictions about DH/RA and RVR minimums, depending on each case. The FAA considers that these cases depend on weather conditions, where “visual references are adequate for manual rollout in CAT IIIa, to an area where visual references are inadequate even for taxi operations in CAT IIIc” (p. 4-64). 

Also to be noted that by 2017 no operator had been approved for the CAT III-c operation in the USA. 

REFERENCIAS

Federal Aviation Administration. (2017). Instrument Procedures Handbook.

Recuperado de: https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/

Aporte Piloto Oswaldo Moreira