How to Understand an FAA ILS Approach Chart

This somewhat complicated document describes how you will get your aircraft down safely in instrument conditions with a precision approach. At first glance an ILS approach chart seem like a daunting document to understand. By dicecting this document into different areas of information you will be able to understand the approach, and know where to look in the document for different pieces of information.

Difficulty: Moderately Challenging

Instructions

Things You'll Need:

• IFR Certified NAV radio and VOR instrument with glideslope
• DME

1. 

   The header section of the aproach chart displays the name of the aproach (in this case, 'ILS RWY 17R', as well as the name and location of the airport for the approach (Lincoln Municiple Airport, Lincoln, Nebraska).

2. 

   Towards the top of the chart is a list of all COM radio fequencies used at the airport as well as in the approach environment. It shows both standard VHF frequencies and miliray frequencies where enabled.

3. 

   In a corner of the main aproach chart window, is the Minimum Safe Altitude (MSA) chart. Some times divided into sectors, this shows the minimum safe alititude from terrain and obstructions within a given distance of the primary navigation beacon for the approach.

4. 

   The first place to start the approach is Initial Approach Fix (IAF). The IAF box describes the point at which the instrument approach begins. This is usually a radio beacon. The approach diagram will indicate the type and freaquency of the beacon, along with its morse code identifier.

5. 

   A path from the IAF to the localizer interception point is shown in the approach diagram. It depicts the entry path to fly to join the localiser. This may include a procedure turn. The headings for this path, as well as the inbound localizer course are shown.

6. 

   The localizer path will pass through the outer, middle (if installed) and inner markers to the landing runway, which is also shown on the approach diagram. The frequency and morse code identifier for the localizer beacon is indicated as well.

7. 

   The main digram shows the horizontal flight path, below which is a vertical navigation diagram. This shows the vertical path to fly while executing the approach. This vertical path will also start at the IAF, and show minimum altitudes to maintain at each key position on the approach. There is also a text description of the missed approach procedure. In this example, cross the IAF above 3000 feet, decend and maintain 3000 on an outbound heading of 324, until inbound on a heading of 174. Decend to 2900 feet until the outer marker, then decend on the glide slope.

8. 

   On FAA approach charts there is an airport diagram which shows how the approach path intercepts the airport environment. The diagram also describes the types of approach lights availble on the different runways. The field elevation is indicated in the top left corner.

9. 

   Finaly, there is a table that indicates how many minutes it takes from the Final Aproach Fix (FAF) to the Missed Approach Point) MAP depending on the speed of the aircraft.

Tips & Warnings

• Remember to allways check the morse code of the IAF beacon and also the localizer beacon to ensure you have the correct frequency.
• Although you may reach the decision height at or near the middle marker, the charted MAP for an ILS approach is the point where the glide slope intercepts the decision height. This point may, or may not be at the middle marker.
• It is not unusual on an ILS approach to establish visual contact with at 500 to 600 feet AGL and the lose outside visual references as the decent continues. For this reason you should avoid descents below the glide slope before you reach DA, even though you have visual contact with the runway.

[dengineer]

on 6/27/2009 This is great!! I am studying for PPL now.. I'm going to have to come back to this article again.
Thanks,