PRESSURE 57 



6430. Determine the amount of pressure change (pp) in accordance with 

 316321, and use Code Table 16 to convert the value to millibars and tenths. 

 Enter the amount, without the decimal point, in column 2 7. Example: A 

 pressure change of 3.9 millibars would be entered in column 27 as 39. 



6431. When the amount of the barometric pressure change equals or 

 exceeds 9.9 millibars, the group "99ppp" should be inserted in the message 

 following the "DgVgapp" group. The "99" is the group identifier, and "ppp" 

 is the total amount of the pressure change (in tens, units, and tenths of 

 millibars) during the preceding 3 hours. When the group is inserted, "99" 

 should be reported for "pp" in the "DgVgapp" group. For example: If the 

 total amount of the pressure change is 13.4 millibars, the groups should be 

 coded "DsVsa99 99134." If the amount is 9.9 millibars, the groups are coded 

 "DgVga99 99099." ("DsVga" should be given appropriate values.) 



