What must be restated when a route or altitude in a clearance is amended?

When a route or altitude in a clearance is amended, it is essential to restate all applicable altitude instructions to ensure clarity and compliance with the updated clearance. This ensures that the pilot has the complete and correct understanding of their altitude requirements, especially in cases where multiple altitude instructions might be involved due to the amendment.

Restating only the new altitude (the first choice) would not provide the full context or the safe operational framework since other altitude instructions may still apply. The option focusing on previous maneuvers in the initial clearance is not relevant because those maneuvers are typically encompassed within the overarching clearance that includes any new amendments. Lastly, only addressing changes to the departure time does not cover the critical adjustments necessary for safe navigation and adherence to air traffic control directives, which is the primary concern when a route or altitude is modified.

By restating all applicable altitude instructions, air traffic controllers ensure that the pilot is fully aware of their responsibilities and maintains safety during the flight, avoiding potential miscommunications that could arise from overlooking other altitude directives.