ATPL Radio Navigation - Class 7: ILS.

Summary

This video script provides an in-depth explanation of the Instrument Landing System (ILS) and its critical components, including localizer and Glide slope signals. It covers how the system works, how pilots interpret visual cues like diamonds on the PFD, and the sensitivity required for accurate landings. The script also discusses common errors, such as false Glide slopes, and emphasizes the importance of approaching the Glide slope from below. Additionally, it touches on the limitations and use of back course approaches in Europe, stressing safety and precision in aviation operations.

Takeaways

• 😀 The ILS (Instrument Landing System) includes the Glide Slope and Localizer, which help guide pilots during landings.
• 😀 The HSI (Horizontal Situation Indicator) displays a diamond that moves to indicate if the aircraft is on the correct flight path, with diamonds above signaling a need to fly up and diamonds below signaling a need to fly down.
• 😀 Modern PFDs (Primary Flight Displays) show two diamonds: one for the Localizer and one for the Glide Slope, each with specific tolerances for deflection (2.5° for Glide Slope and 0.75° for Localizer).
• 😀 Signal disruptions around ILS systems require awareness of sensitive areas to avoid errors and ensure a stable approach.
• 😀 False Glide Slopes, such as those twice the angle of the normal Glide Slope, can occur and must be avoided by intercepting the correct Glide Slope from below.
• 😀 Back course approaches are not allowed in Europe due to the potential for confusion, where flight indications could be reversed (e.g., 'fly left' means fly right).
• 😀 The maximum deflection values of 2.5° (for Glide Slope) and 0.75° (for Localizer) indicate the allowable limits for proper alignment.
• 😀 Intercepting the Glide Slope from below is important to ensure the aircraft follows the correct path and avoids potential false Glide Slopes.
• 😀 When flying in critical ILS areas, it is crucial to cross-check the aircraft’s height and distance to ensure alignment with the correct Glide Path.
• 😀 While back course approaches are not permitted for landings in Europe, they may be used for specific departure procedures.

Q & A

What is the primary function of the Instrument Landing System (ILS)?

The primary function of the Instrument Landing System (ILS) is to provide pilots with precise guidance for approaching and landing an aircraft, especially in low visibility conditions, by using radio signals for horizontal (localizer) and vertical (glide slope) guidance.

How is the localizer signal represented on the Primary Flight Display (PFD)?

The localizer signal is represented on the PFD by a horizontal line or diamond that indicates the aircraft's position relative to the centerline of the runway. If the diamond is displaced to the left or right, the pilot is required to adjust the aircraft's heading to realign with the runway.

What does it mean when the glide slope diamond is above or below the aircraft's current position on the PFD?

If the glide slope diamond is above the aircraft's position on the PFD, the pilot needs to fly upward to reach the correct glide path. If the diamond is below, the pilot needs to descend to re-align with the glide slope.

What is the maximum deflection of the localizer and glide slope signals?

The maximum deflection for the localizer signal is typically 2.5 degrees, and for the glide slope signal, it is 0.75 degrees. Beyond these deflections, the signals become unreliable, and the system may fail to provide accurate guidance.

What causes false glide slopes, and why are they important for pilots to recognize?

False glide slopes are caused by echoes of the actual glide slope, typically positioned above the real path. They can mislead pilots into thinking they are on the correct glide slope. The most common false glide slope is double the angle of the real glide slope. Pilots should always intersect the glide slope from below to avoid confusion.

Why are back course approaches generally not allowed in Europe?

Back course approaches are not allowed in Europe because they can cause confusion, as the aircraft's navigation equipment works in reverse. For example, 'Fly Left' would mean the pilot should fly right, and 'Fly Right' would mean flying left, which can be dangerous in certain conditions.

What is the advantage of approaching the glide slope from below?

Approaching the glide slope from below is safer as it helps pilots to avoid false glide slopes and ensures they are correctly aligned with the real glide path, improving the accuracy and reliability of the approach.

How do modern glass cockpit systems display the glide slope and localizer signals?

In modern glass cockpits, the glide slope and localizer signals are each represented by their respective diamonds on the Primary Flight Display (PFD). One diamond indicates the aircraft's position relative to the localizer, and the other indicates the vertical position in relation to the glide slope.

What are the critical areas surrounding the ILS system that pilots need to be aware of?

The critical areas surrounding the ILS system are zones where signal disruption can occur. Pilots must fly with heightened awareness in these areas to avoid errors, as the ILS signals can become unreliable, especially when sensitive equipment is involved.

Can back course approaches be used for departure procedures?

Yes, while back course approaches are generally not used in Europe for landing due to confusion, they can be used for departure procedures where the reverse signal direction might not pose a problem.