Updating Charts for Tower and Obstructions

CHAPTER 7

AIR FORCE T-38 TRACK INTERMEDIATES

704.

UPDATING CHARTS FOR TOWERS AND OBSTRUCTIONS

The National Imagery and Mapping Agency (NIMA) produces new edition charts every five

years. Unfortunately, details on these areas change much more frequently. So, what is a pilot to

do to find out if a new 1700-foot tower has been built along their planned flight route? NIMA

has thought about this and produces a manual called the CHUM, or Chart Updating Manual.

This publication is published on a semi-annual basis with supplements being produced each

month.

A CHUM update in the manual will look something like this:

Change:

Tower 265-607 to multi towers 31 05 58N

88 13 51W

Add:

Tower, 310-391

31 14 46N

87 44 03W

Find the coordinates on your chart and update them with the new information. Now you are

ready to start plotting your course! But wait, where can I fly this route? Let us look at some

defined, preplanned low level corridors.

705.

AP/1B, IR/VR ROUTES

Military training routes are found in the AP/1B. These are predetermined corridors for low

level military training and come in three flavors: IR, VR, and SR routes. The AP/1B provides

textual and graphic descriptions, and operating instructions for all military training routes, both

low level and air refueling. Information provided includes type of route, length of route,

direction of flight on the route, entry/exit points, and of course definition of the three main types

of routes.

706.

IR ROUTES

IR routes, or instrument rules routes, must be flown on an IFR flight plan regardless of weather

conditions. Your flight plan must include the entry fix/radial/distance, the route designator, and

the exit fix/radial/distance. You must enter/exit the route via published entry/exit points or

published alternate entry/exit points. You must also have a specific ATC clearance prior to

entering the route. When on the route you must remain within the confines of the route

corridors, both width and altitude. When practical you should avoid flight within three NM and

1500 feet AGL of airports. IR routes are designed so that specially equipped aircraft may fly

them in IMC/night conditions.

707.

VR ROUTES

VR routes, or visual rules routes, are much less restrictive. You should be on a VFR flight

plan, but are required to only have the fix/radial/distance of your entry point, not the exit point

(unless you intend to get an IFR clearance at the end of your low level). You must still avoid

airports by three NM and 1500 feet AGL and maintain VFR weather minimums.

7-4 T-38 LOW LEVEL NAVIGATION