The ILS-DME CATIIIA Approach

Hi. Mexico's only ILS CATIII approach is in Toluca. Other countrys have many more aiports with CATII/III approaches.

Here are the differences of the ILS Categories (ICAO):

a. ILS Category I - An ILS approach procedure which provides for an approach to a decision height not lower than 200 feet (60m) and a visibility not less than 2400 feet (800m) or a runway visual range not less than 1800 feet (550m).

b. ILS Category II (Special authorization required) - An ILS approach procedure which provides for an approach to a decision height lower than 200 feet (60m) but not lower than 100 feet (30m) and a runway visual range not less than 1200 feet (350m).

c. ILS Category III (Special authorization required) -
1. IIIA - An ILS approach procedure which provides for approach with either a decision height lower than 100 feet (30m) or with no decision height and with a runway visual range of not less than 700 feet (200m).

2. IIIB - An ILS approach procedure which provides for approach with either a decision height lower than 50 feet (15m) or with no decision height and with a runway visual range of less than 700 feet (200m) but not less than 150 feet (50m).

3. IIIC - An ILS approach procedure which provides for approach with no decision height and no runway visual range limitations.

Taken from the Jeppesen Airway Manual.

Now here's the Toluca ILS-DME Rwy 15 CATIIIA approach:

So, with the chart in hand, we can see in the header section, appart from the information we already know how to read, we must refer to the minimums section to check the CATIIIA minimums.

In the minimums section we see two parts: CATIIIA ILS and CATII ILS.
· In CATIIIA ILS, the RVR (Runway Visual Range) is presented with readings in hundreds of feet. So in this example, RVR 7 means 700 feet.
· In CATII ILS, the left column lists the lowest available CATII minimum, normally DH 100, visibility RVR 12 (350m). The right column lists the CATII minimum applicable when certain airborne equipment is out of service or when pilot and operator requirements preclude the use of lower minimum. The minimum is normally DH 150, visibility RVR 16 (500m).

With this type of approach, I've finished all approach types there are in Mexico. As I wrote in a previous post, I'll show different charts and approaches.

Bye.