Definition
The point in the FAA's instrument chart revision cycle, ten calendar days before a new chart edition becomes legally effective, by which newly issued or amended instrument procedures and chart changes are typically published and made available to pilots for review and preparation.
Plain English
It is a date ten days before new instrument charts officially take effect. By this point the updated charts are out, so pilots can study them and be ready to use them on the day they become valid.
Context Anchor
Seen when studying FAA chart revision cycles, especially for instrument procedure charts and chart updates.
Derivation
“Prior” means before. “Effective” means in force or active. In this phrase, the key idea is not when the chart is printed or received, but when it becomes the chart that is valid to use.
Why Pilots Care
Missing this window can leave pilots flying with procedures that are not yet synchronized with the published charts, creating a safety gap.
Intuition Check
Do not read this as “the charts are usable 10 days early.” It means they may be available 10 days early, but they become valid on the effective date.
Example Sentence 1
The amended approach plate was published 10 days prior to the effective date of the charts, giving crews time to brief the new minimums before they took effect.
Example Sentence 2
All coordination for the new approach must be complete 10 days prior to the effective date of the charts or the revision will be delayed.