How to Fly an ILS Approach

The instrument landing system (ILS) is a precision approach aid which provides highly accurate, glide slope, and distance guidance to a specific runway. The ILS approach is the best approach alternative in poor weather for a number of reasons. It provides more accurate guidance information than any approach system, allowing for lower approach minimums. These lower minimums allow you to land at airports that would otherwise be unavailable using a non-precision approach

Instructions

Difficulty: Moderately Challenging

Things You’ll Need:

• Working NAV receiver with Glide Slope capability
• DME

1. Transition from enroute to the approach.
2. While inbound on the localizer, establish the required wind drift corrections before you reach the outer marker. As the course narrows, make small drift corrections and reduce them proportionally.
3. While inbound on the localizer, establish the required wind drift corrections before you reach the outer marker. As the course narrows, make small drift corrections and reduce them proportionally.
4. Upon intercepting the glide slop, begin a decent to stay on the glide slope. You will usually need to reduce power, and adjust your pitch. Use small pitch changes to maintain the glide slope, and use power to maintain a constant approach speed.
5. If you maintain the glide slope for the approach, you should reach the decision height (DH) at about the middle marker.
6. Prior to DH, you should cross-check with only brief glances outside until you are sure that you have established positive visual contact with the runway environment.
7. Once visual contact has been made prior to DA or Minimum Decent Alititude (MDA), you may continue your descent provided you maintain visual contact with the runway until touchdown. Should you loose sight of the runway below DA or MDA you must execute a missed approach.

Tips & Warnings

• If the glide slope approaches full scale deflection, respond immediately with pitch and power adjustments to re-intercept the glide slope.
• Localizer and glide slope indications become more sensitive as you get closer to the runway. On a well execute ILS in calm wind conditions, you should not need heading corrections greater than 2 degrees after you have passed the outer marker.
• 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.