Practice question

According to ICAO Annex 11 and Annex 12, when is the Alert Phase (ALERFA) initiated by an air traffic services unit?

  1. Immediately when an aircraft takes off from a military base
  2. When, following the uncertainty phase, subsequent communication attempts fail, or when an aircraft has been cleared to land and fails to land within 5 minutes of ETA with communication lost
  3. Only after 24 hours have elapsed without contact
  4. When an aircraft requests an altitude change due to light chop

Answer: B — When, following the uncertainty phase, subsequent communication attempts fail, or when an aircraft has been cleared to land and fails to land within 5 minutes of ETA with communication lost

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