text: Ground Tactical Plan
  Assaultobjectives aresecuredbeforethedefenseissetupintheairheadline.The airheadis
  (cid:132)
  then cleared of organized enemy resistance and forces are positioned to secure the airhead
  line.
  4-28. When commanders select assault objectives, they should consider the extent of the airhead. The
  airhead includes the entire area under control of the airborne force. It acts as a base for further operations
  and as a respite that allows the airborne force to build combat power. Once the force secures the airhead,
  theymustclearenemyforceswithinit;then,theymustdefendit.
  4-29. The airheadlineisalinedenotingthelimitsofthe objective areaforanairborneassault(JP 3-18).It
  delineates the specific area to be seized and designates the airhead. Several principle factors determine the
  location,extent,andformoftheairheadorairheadline,theyareasfollows:
  (cid:122) The actual trace of the airhead line reflects the control of key or critical terrain essential to the
  mission.(Seefigure4-2.)
  Figure 4-2. Airhead line
  (cid:122) Theairhead line anchors onobstacles,andtheairheaditselftakesadvantage ofnaturaland man-
  madeobstacles.
  (cid:122) The airheadcontains enough dropzonesandlanding zonestoensureinteriorratherthan exterior
  linesofcommunicationandtopermitmassratherthanpiecemealassault.
  (cid:122) The airhead must allow enough space for dispersion to reduce vulnerability to chemical,
  biological,radiological,nuclearweapons.
  (cid:122) The airhead mustbe large enoughto provide fordefense indepth, yet small enough for the unit
  to defend.Although this islargelyMETT-TCdependent,abattalioncandefendan airhead three
  to five kilometers in diameter. An IBCT can occupy an airhead five to eight kilometers in
  diameter.
  SECURITYANDRECONNAISSANCE
  4-30. Security in all directions is an overriding consideration early in the airborne operation, since an
  airheadorlodgmentisessentiallyaperimeterdefense. Anotheroverridingconsideration,theairborneunit’s
  method of arriving into the objective area requires the conduct of an immediate and thorough
  reconnaissance and the rapid transmission of this information to higher headquarters. Security operations
  andreconnaissancemissionswithinthesecurityareaenabletheseefforts.