Multiple choice

Which of the following frequencies cannot be an ILS frequency?

  1. 109.30 MHz

  2. 110.50 MHz

  3. 110.80 MHz

  4. 111.70 MHz
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

ILS (Instrument Landing System) frequencies are in the range 108.10-111.95 MHz, but only odd frequencies are used: 108.10, 108.15, 108.30, 108.35, etc. 109.30 MHz and 111.70 MHz are valid odd frequencies. 110.80 MHz ends with .80 (even), which is not a valid ILS frequency.

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