At any time, if the current ATIS (Automatic Terminal Information Service) does not reflect the current situation (including changes in weather), controllers must change the ATIS without delay and relay this to the other controllers involved. The following is the reasons why a controller may change the ATIS phonetic letter:
- Upon recipient of any new official weather regardless of whether there is or is not a change in valued
- A runway is removed or added
- A REMARK or NOTAM is added or removed
- The addition or removal of new or different frequency instructions
If any of the following are changed then the controller would publish a new ATIS with a new phonetic letter, then ensure all pilots and controllers are operating under the same information by broadcasting that a change has been made on all active frequencies.