Frequency of Issuance WEAX/AVWX  service  is  available  for  both  in  port and underway periods. In port WEAX/AVWX will only be issued if requested and if the unit is not in a port supported by one of the NAVMETOCCOM activities listed   in   NAVMETOCCOMINST   3140.1.   In   port WEAX/AVWX  are  issued  once  daily. As  a  ship  passes  from  one  NAVMETOCCOM center’s  area  of  responsibility  to  another,  the  forecast responsibility  is  automatically  passed  between  the centers. Ships will be advised when this occurs in the Remarks  section  of  the  WEAX/AVWX  message. When   WEAX/AVWX   service   is   requested, forecasts will be provided at least once per 24-hour period and updated whenever a significant change in the forecast   occurs,   whether   caused   by   atmospheric changes or changes in the ship’s operating area or route. WEAX/AVWX will be issued to a unit twice daily when  located  within  areas  bounded  by  wind  and  high sea  warnings,  and  when  conditions  exceed  those specified by a unit involved in towing, salvage, or other unique operations that require tailored support. During  minimize,  only   units   experiencing conditions  listed  in  the  previous  paragraph  will  receive routine  WEAX/AVWX.  All  other  units  will  receive  an initial  WEAX/AVWX  when   minimize  is   imposed. Updates will be provided only when conditions are forecast to exceed those listed in the previous paragraph during the 48-hour outlook period. Product Consideration Wind, sea, and tropical cyclone warnings, and so forth  will  be  referenced  in  the  WEAX/AVWX  message when applicable. For more information in this area, see NAVMETOCCOMINST    3140.1. WEAX/AVWX  STANDARD FORMAT Table  10-3  shows  the  standard  format  used  by NAVMETOCCOM  activities  responsible  for  providing WEAX/AVWX  services. The WEAX/AVWX meteorological situation will include the locations of pertinent high-and low-pressure centers. The bearing and range from a geographical reference point or from the unit receiving the forecast will  be  specified. Appropriate items in subparagraph 2G of table 10-3 will  be  included  when  the  MOVREP  indicates  an aviation unit is embarked, or if otherwise requested. Significant convective activity within 100 nmi of the ship will be included. AVWX forecasts will be issued twice  daily  when  visibility  and/or  ceiling  is  at,  or decreases below 3 nmi or 1,000 ft. If the difference between  sea  and  swell  direction  and/or  height  is significant,  it  will  be  indicated. An  Alfa  index  forecast  will  be  included  in subparagraph  2H  of  table  10-3  for  light  airborne multipurpose system (LAMPS) capable ships, When refractivity  data  based  on  upper  air  soundings  are available,   information   regarding   radar/radio performance   predictions   and/or   refractive   index structure  data  tailored  to  the  ship’s  radar  configuration may  be  included  in  this  paragraph.  Requests  for refractivity  data  should,  when  possible,  include  a current  upper  air  sounding.  For  more  information  on WEAX  and  AVWX  support,  see  the   U.S.  Navy Oceanographic  and  Meteorological  Support  System Manual,  NAVMETOCCOMINST  3140.1.  Refer  to NWP’s  65-0-1  and  65-0-2,   Characteristics   and Capabilities of U.S. Navy Combatant Ships,  which list the types and characteristics of radar on USN ships. AIRCRAFT DITCH HEADING FORECASTS LEARNING  OBJECTIVES:  Be  familiar  with the procedures for obtaining the ditch heading product. Recognize the characteristics of the product. Identify its uses. Navy aircraft are routinely involved in oceanic flights. In the event of an in-flight emergency, a pilot must  make  a  decision  on  which  direction  to  ditch  the aircraft. PRODUCT DESCRIPTION The NODDS ditch headings product provides a graphic  depiction,  using  arrows,  to  show  the recommended  direction  into which  an  aircraft  should land on a water surface. Directions are calculated from 0 to 359 degrees relative to magnetic north. 10-8