text: _________________________________________________________________________________Chapter 9
  carriages and missile launchers to jamming or to destruction by antiradiation
  missiles (ARMs) or other means.
  9-120. The air surveillance radar network is difficult to avoid or defeat. Many
  air defense radars are highly mobile and can displace quickly. Fire control
  units turn on radars at the last minute to achieve surprise and to avoid exposing
  themselves to enemy electronic or physical attack. The more advanced radar
  systems have enhanced electronic protection from jamming and ARMs. The
  wide spread of operating frequencies makes jamming difficult. Operator training
  stresses electronic counter-countermeasure skills and the use of radio and elec-
  tronic silence where possible. Units back up radar reconnaissance with visual
  observation. Maneuver units have a radio net devoted exclusively to the passage
  of air and NBC warnings. Radar provides an all-weather detection capability.
  Visual Observation
  9-121. Despite the presence of a technologically advanced early warning
  system, the OPFOR continues to stress the importance of visual observation.
  Air defense and maneuver units deploy air observers as a backup to radars
  and so air defense units may not need to use their radars. In later stages of
  combat against more modern opponents, the OPFOR may have to rely
  heavily on observers after losing much of its radar capability.
  9-122. An effective system of visual observation may often provide the first
  warning of an enemy air attack, especially one conducted by low-flying aircraft
  or armed helicopters using NOE techniques. When operating close to enemy
  forces or in areas where enemy air attack is considered likely, all units post
  air observers. In the defense, air observation posts are set up at suitable loca-
  tions, usually on terrain offering good visibility, near CPs, and/or close to air
  defense units in firing positions. During tactical movement and during both the
  defense and offense, observers are posted on each vehicle. Observers are
  changed frequently to reduce fatigue and maintain their effectiveness.
  9-123. Whenever possible, the OPFOR tries to get SPF teams, human intelligence
  (HUMINT) agents, or sympathetic civilians to visually observe enemy airfields
  in or near the region. These observers report by radio or telephone the number
  and types of aircraft taking off and their direction of travel. Other observers
  stationed along probable approach routes can monitor and report the progress of
  the enemy aircraft en route to their targets. Thus, OPFOR air defense units may
  not need to use their radars to detect and track incoming aircraft.
  REQUIREMENTS
  9-124. The information required by air defense units falls into two categories:
  information on enemy air actions and information that can complete the pic-
  ture of the overall air situation. The first category is a joint responsibility of
  all reconnaissance forces, and the second is the specific responsibility of air
  defense reconnaissance units.
  9-125. The first category includes data from which the OPFOR can determine
  probable enemy air actions. This information is critical for planning and or-
  ganizing the air defense system. Such information could include—
  • The composition and strength of enemy air power.