Andrews 



THE SECOND OPERATIONS ANALYSIS (POST-OPERATION) 



The secoad analysis, conducted after the operation, sought to 

 determine any relation between acoustic and visual search. A plot 

 of all visual contacts was made. This was then considered to 

 represent the true picture of debris and rock distribution on the 

 ocean floor off Palomares. Figure 7 shows this plot. An important 

 point to note is the high debris density in All and the great number 

 of rocks also sighted in All. The location of the nuclear weapon is 

 shown. 



With this chart and with data available from the contact logs, 

 each acoustic contact was reviewed and placed into one of the 

 following categories. 



NF - no visual follow-up 



NS - no sighting in the visual follow-up 



OC - a sighting was made in the visual follow-up and 



its position, its depth, and for OBSS only, the 



approximate size of the contact correlated with 



the acoustic report 

 CD - a sighting was made but only one of the criteria 



sited under OC seemed to correlate with that 



initially reported by acoustics. 



A correlation in position was considered to have occurred if 

 the reported acoustic position was within 500 yards of the reported 

 visual position. For depth the figure was 80 feet. For correlation 

 in dimension, agreement within 1-2 feet for large objects and 50% 

 for small objects was required for one dimension only. The other 

 dimension had to agree within only an order of magnitude. 



The contacts in categories CD and OC were further divided by 

 considering (a) the availability or nonavailability of DECCA to 

 both detection and classifier units, (b) the location of the contact 

 in an area of high or low density as determined by the chart of 

 visual contacts. Figure 8 gives a summary of the analysed data for 

 the UQS-1 and OBSS Sonars. The large number of OBSS contacts in 

 Class NF was due to lack of time to follow-up all reported contacts 

 and the fact that many of these contacts were outside of the 

 priority areas AI and All. 



The significant conclusions from this study were 



1. The use of the OBSS sonar in SALVOPS/MED was relatively 

 ineffective because of the tactics used, the high percentage of 

 rocks in the operations area and the conduct of part of the OBSS 

 search prior to the availability of DECCA. 



Specifically OBSS was ordered to make single passes through 

 an area once with a small overlap. No attempt was made to regain 



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