Is Expired Data Useable?
Reprinted from IFR Magazine June 2013 -
There is no question that pilots planning to fly IFR should always keep a current database in their approved GPS. It's not difficult and it demonstrates a professional attitude toward instrument flight and aircraft maintenance. In the perfect black and white world of flight schools and checkrides, this would be standard. However, in the real world of dumb luck and Murphy's Law, this topic gets a little murky.
What happens when your database is current when you take off, but expires before you reach your destination? How about departing with an expired database with plans to avoid GPS approaches, only to encounter an emergency and, as luck would have it, the nearest airport has only GS approaches In hindsight, it would have been a good idea to have just updated the database, but nevertheless, you still need to get down safely.
Thankfully, the FAA offers some surprisingly pragmatic guidance in this matter. AIM 1-1-19 states that flying an IFR approach with an approved GPS "requires current database or verification that the procedure has not been amended since the expiration of the database" (emphasis added). The question becomes how to wade through all the dates found on a procedure so that you can determine whether it has been amended.
Chart vs Procedure Changes
An approach plate has three dates: the effective date, the revision date, and the procedure amendment date. Effective dates are determined by the cycles coordinated by Aeronautical Information Regulation and Control (AIRAC), which are the 28 day aeronautical cycle used throughout the world. These cycles set the schedule for when your database needs to be updated, and are the reason behind AeroNav's (FAA) 56 day publication schedule and 28 day change notices. Jeppesen charts also have an issue date, which relates to their production schedule, but they don't correspond to the AIRAC cycle dates, although any effective dates will. This can get confusing in that AeroNav publishes each chart each cycle while Jepp only reissues a chart for a change.
For the purposes of determining whether a chart has been modified, we're most interested in the date of the last revision and the procedure amendment effective date. On AeroNav charts, the date of the last revision is depicted as a Julian date (year plus day number, eg. 13178 for the 178th day of 2013, or June 27th), either in the top right or bottom left corner. For Jepp charts, unless there is an explicit effective date, the date of last revision is the issue date and is considered effective upon receipt.