Introduction / Context:
This question assesses understanding of key ILS and runway concepts: the runway threshold, localizer, glide slope, and marker beacons (LOM/LMM). These elements guide aircraft laterally and vertically for safe approach and landing, especially in reduced visibility.
Given Data / Assumptions:
- Runway threshold is the runway end available for landing from the approach direction.
- Localizer provides lateral (left-right) guidance relative to runway centerline.
- Glide slope provides vertical path (angle of descent) guidance, commonly near 3 degrees.
- LOM (Locator Outer Marker) and LMM (Locator Middle Marker) assist pilots in distance/position awareness along the approach path.
Concept / Approach:
ILS integrates a localizer (lateral) and glide slope (vertical) with additional aids—markers and/or DME—to form a precise approach. Threshold markings and lighting indicate the beginning of landing-usable runway.
Step-by-Step Solution:
Statement 1: Threshold definition is correct—the end of the runway from the landing side used for touchdown reference.Statement 2: The localizer indeed indicates position relative to the intended alignment (centerline).Statement 3: The glide slope indicates the correct approach angle to maintain a stabilized descent.Statement 4: LOM and LMM are radio beacons that help judge position and distance during approach. Correct.
Verification / Alternative check:
Cross-check standard ILS descriptions: LOC (lateral) + GS (vertical) + markers or DME for distance gives a complete guidance picture.
Why Other Options Are Wrong:
Any option omitting one of the statements fails because all four statements are standard definitions/functions in ILS operations.
Common Pitfalls:
Confusing threshold with runway end safety area; confusing localizer with VOR; assuming glide slope is variable without limits.
Final Answer:
All of the statements (1–4) are correct.
Discussion & Comments