The Pack feature creates an "envelope" around your planned route and checks to see which items need to be downloaded. The envelope covers 25nm either side of the enroute course and within a 50nm radius around the destination and departure airports.
Pack will always check for the latest METARs, TAFs, AIR/SIGMETS, TFRs, Fuel Prices, NOTAMs, Documents, Airport Database, and Obstacles.
You can set up which type of chart and map data that you want PACK to check for by going to MORE > DOWNLOADS > UNITED STATES or CANADA > and select options such as IFR Low, Terminal Procedures, or VFR Charts. Pack only offers downloads for those items that are not already downloaded to your device.
The information that is downloaded using Pack is accessed during the normal use of ForeFlight. Weather can be found from Map overlays and on the Airports Page. Terminal Procedures can be found from within the Airports Page or by searching for them on the Plates Page. NOTAMS are displayed within the Airports Page.
You can view which states are downloaded by Pack and delete unwanted states by going to MORE > DOWNLOADS > Swipe from right to left on the states that you no longer need. Because the state is not selected under the United States sections of Downloads, when it expires it will be deleted from the system automatically.
If your route is changed, PACK will re-evaluate the downloads and re-alert the you of any available downloads. Every 10 mins Pack will recheck the current route for new weather and NOTAMs.