movement is the service ceiling of the aircraft itself. This is particularly true
in the case of rotary-wing aircraft which have low-service ceilings. Major terrain
features often force rotary-wing aircraft to use valleys for their approach to the
target, again canalizing movement and restricting maneuver. A final obstacle to
aircraft movement is certain types of ordnance require a minimum release altitude
or attack profile.
Obstacles which should be considered during airborne and air assault operations
include flooded areas, areas with second-growth timber, and areas where the enemy
has placed synthetic antilanding obstacles such as posts, dragons teeth, and
shallow crisscross ditches. Jungle clearings often appear to be ideal LZs or DZs.
However, these areas often have exceptionally tall grass which deceives the
observer as to the actual ground height. This situation creates an unexpected drop
of between 8 and 12 feet for troops descending by parachute or exiting an aircraft.
The final obstacle that must be considered when conducting airspace analysis is the
actual soil composition of the ground environment. Excessive amounts of blowing
dust and sand can severely damage aircraft engines, as can small stones drawn into
engine intakes. Thus, the soil in an area can impose special maintenance,
logistics, and operational constraints on aviation operations.
Key terrain in airspace analysis is any terrain feature which allows air defense
weapons to engage canalized or constrained air or airborne forces. Areas that
limit aircraft lateral movement, restrict air maneuver, or have elevations higher
than maximum aircraft service ceilings should also be considered key terrain.
Other areas which should be considered key terrain include--
* LZs and DZs.
* Fixed or surveyed air defense weapons and radar sites.
AVENUES OF APPROACH
Airspace avenues of approach are evaluated by the same criteria as ground avenues
of approach. A good air avenue of approach permits maneuver while providing
terrain masking from air defense weapons systems. Figure 7-6 shows an example of
an air avenue of approach. Additional variables considered in analyzing the air
avenues of approach include the--