Originally Posted by newifr
2. What does S-I ILS mean as opposed to ILS.
Hi newifr,
I assume you're using Airservices plates based on this comment. There are actually two - ILS-Y and ILS-Z - but the layout is the same. Each has five minima fields, as follows (using the ILS-Y, the -Z is the same but the MAP gradients are less):
S-I ILS (2.5% MAP) - this is the minima for a straight-in approach to RWY35, if you can meet the 2.5% MAP climb gradient.
S-I ILS (5.0% MAP) - this is the minima for a straight-in approach to RWY35, if you can meet a 5.0% MAP climb gradient (to 3200FT, then relax to 2.5%, explained in the plate notes)
S-I LOC/DME - this is the minima for a straight-in approach without glidepath guidance
CIRCLING - this is the minima if your approach will require circling, ie the ILS is the only suitable approach, but the wind velocity makes 35 operationally unacceptable to you.
ALTERNATE - the alternate minima for the airport.
Both the Circling and Alternate minima are the same for every approach, and in Canberra the alternate figures are a reasonably standard 500ft / 2.0km greater than the circling minima for the respective performance category.
AIP provides the guidance that:
Originally Posted by ENR 1.5 para 6.1.1
Each approach chart shows the ceiling and visibility minima to be compared with meteorological forecasts and reports to determine both the need to provide for an alternate aerodrome and the suitability of an aerodrome as an alternate.
You should seek guidance from your instructors about what their expectations are regarding planning when your destination is at or near its alternate minima. The wording of the Regulations, and individual company policies, can vary widely on this point.