Let's pick up with the AIP amendment system — Page 360, Lesson 480

Let's pick up with the AIP amendment system. Permanent changes to the AIP are published as AIP amendments. Each amendment gets a consecutive serial number, and every amended page—including the cover sheet—shows the publication date. So the serial number tells you the order, and the date tells you when it went out. Now, the big one: AIRAC. That stands for Aeronautical Information Regulation and Control. Operationally significant changes to the AIP are published under AIRAC procedures, and they must be clearly identified by that acronym. Each AIRAC amendment page, including the cover sheet, must display an effective date—that's the date the change actually takes effect. Here's the rhythm of AIRAC. It's based on a series of common effective dates spaced 28 days apart, and that series started on 10 January 1991. The AIS unit—that's the Aeronautical Information Service—distributes AIRAC information at least 42 days before the effective date. And once notified, that information must not be changed for at least another 28 days after the effective date. There's one exception: if the circumstance is temporary and won't persist for the full period, then it can be changed. And when major changes are planned and extra notice is desirable, you use a publication date 56 days in advance of the effective date instead of 42. Now, AIP Supplements. These cover two situations: temporary changes of long duration—three months or longer—and information of short duration that contains extensive text and/or graphics. Each supplement gets a serial number that's consecutive and based on the calendar year. The pages stay in the AIP as long as all or some of their contents remain valid. If a supplement is sent to replace a NOTAM, it must include a reference to that NOTAM's serial number. A checklist of supplements currently in force is issued at intervals of no more than one month—so monthly or more frequent. And the supplement pages should be coloured to be conspicuous, preferably yellow. So the key contrasts: amendments are permanent, AIRAC is for operationally significant changes with a strict 28-day effective-date cycle, and supplements handle temporary or text-heavy information. Let's look at the figure for surface friction reporting codes next.