LOW-LEVEL AND TACTICAL FORMATION
Ensure your chart covers the entire route of flight, sufficient areas along your route, and alternate
or emergency fields. If you need more than one chart to completely cover the entire route,
overlap the identical features on both charts and tape or glue the charts together. Trim all charts
to a minimum size for ease of handling in the cockpit but be sure not to trim off alternate
airfields. Initially, do not trim your chart any closer than 22 NM of centerline until emergency
safe (ESA) and minimum safe altitudes (MSA) have been calculated. Make sure the chart you
select is current (see CHUM paragraph below).
Mark the Published Points and Draw the Route Corridor. Plot the points defined in the
route description section of FLIP AP/1B. You are not required to use these points as turnpoints
or checkpoints, but they define the centerline of the route from which you will draw the route
corridor. Take your time and plot the points carefully. Draw the route corridor as defined in
AP/1B. One technique is to draw a straight line very lightly in pencil between each published
point and use that line to measure the width of the route corridor. You may want to identify or
highlight the points that conflict with crossing routes. Locally developed routes do not have a
defined route corridor.
Use the CHUM. The CHUM contains a cumulative listing of uncharted obstructions 200 feet
and higher. When vertical obstructions form a multiple complex, only the highest obstruction
within this complex is listed. Plot all CHUM obstructions within 22 NM of course centerline.
First, be sure your chart is current. The National Imagery and Mapping Agency (NIMA) updates
aeronautical charts on a regular basis. Each chart has a basic publication date and an edition
number. Next, find the Chart Updating Manual (CHUM) and the latest monthly CHUM
supplement which list changes (new obstructions, etc.) discovered since the last revision. The
CHUM data can also be obtained electronically by modem, contact NIMA at DSN 693-4005 or
commercial (314) 263-4005. In Figure 1-2, the current edition (13) was last revised in
May 1993. Locate and make all changes to the chart by using the latitudes and longitudes given
in CHUM. Annotate on the chart the date of the CHUM used to update. The route or areas you
will be using are the only areas necessary to update. (The two altitudes listed are for obstruction
heights in AGL and MSL).
LOW-LEVEL NAVIGATION 1-7