UNITED STATES ATLANTIC FLEET
ANTISUBMARINE WARFARE UNIT
 
150 CAUSEWAY STREET
  
 
BOSTON, MASSACHUSETTS
  
 
A16-3 (2)
  
 
Serial 0518
  
 
4/jjc
  
 
 
 
CONFIDENTIAL
  
 
 
 
From: The Atlantic Fleet Anti-Submarine Warfare Officer.
To    : The Commander in Chief, U.S. Atlantic Fleet.
   
Subject : 

VP-74 Anti-Submarine Action by Aircraft Report                 

  #9 dated May 16, 1943: Analysis of.
     
Enclosure: (A) Subject Analysis.
 
 
 
 
            1.             Enclosure (A) is forwarded herewith.
  
 
 
 
            2.             It appears from the comments made by the Squadron Commander on subject report that the squadron's supply of practice bombs has not been materially augmented since the date of reference (a). In reference (a) it was stated that no practice bombs were available at the base.
  
 
 
 
 
 
                                                                                        
 
 
                                                                                                P.R. HEINEMAN.
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 

 
 

 
ANALYSIS OF ANTI-SUBMARINE ACTION BY AIRCRAFT.
 
Unit Report No.     9.
  
 
 
 
Airplane Type   :     PBM-3C.
  
 
 
 
Squadron No.  :     74-P-2
  
 
 
 
Pilot                 :     Lieutenant H.E. Gibbs, USNR.
  
 
 
 
Unit:     VP-74.
  
 
 
 
Location of Attack: Latitude:     10-58 S.
  
 
                              Longitude:        35-59 W.
  
 
 
 
Date:    May 16, 1943.
  
 
 
 
Time:    1357 (Zone plus 3).
  
 
 
 
    1.   The airplane was flying at an altitude of 2500 feet on an anti-submarine sweep mission with good weather and visibility and 5/10 cumulus clouds at 2500 feet.  Radar was being used but did not make the contact.  The man at the bomber’s window made sight contact on the wake of a submarine running with decks awash at a range of 15 miles slightly on the starboard bow.  This contact was confirmed with binoculars, and course changed slightly to make a down-sun run through the base of the clouds and up the track of the submarine.  It appeared that the submarine had decided to submerge some time before the sighting was obtained as it was already slowly going down.  The approach was made at 180 knots, and, when the range had been closed to approximately one mile, the submarine disappeared below the surface.  Some time after the conning tower had disappeared the bomber released six Mark 44 depth bombs with fuses set to function at 25 feet and spaced 72 feet apart by intervalometer.  At that time the altitude of the plane was 50 feet, airspeed about 165 knots, and heading 100 to the right of the course along which the submarine submerged.  The bombs were spaced regularly, beginning with the first which hit the water at a distance estimated as 65 feet from the rear edge of the swirl.  At least three bombs were seen to explode, and the functioning of the remaining three will not be determined until photographs become available.  The plane remained in the area for one and one-half hours after the attack during which time two other planes of the squadron arrived on the scene to continue the patrol.  Shortly after the attack an object about 100 feet long, and about 25 feet wide, and dark brown in appearance was sighted about 100 yards from the point of explosion, but it could not be identified.  No evidence of damage was observed.
  
 
 
 
    2.   This attack came on the sixth day of a seven and one-half day concentrated air-surface hunt which had been ordered following the receipt of an RDF contact.  It is considered that the pilot used very good judgment in utilizing one of his gambit absences from the area to make a landfall and check the position of the attack.  His approach to the attack was well done, and the photographs of the action which, the report states, are to be forwarded later may indicate whether the bombs should have been released or withheld.
  
 
 
 
- 1 -
 
 
 
 
 

 

 
 

 
ANALYSIS OF ANTI-SUBMARINE ACTION BY AIRCRAFT.
 
    3.   The report indicates considerable confusion in the matter of determining the range at which the submarine submerged and the interval between the times of submergence and bomb release.  According to the stopwatch, the time interval was 1 minute 5 seconds, and this is more or less corroborated by the estimates made by several members of the crew.  Observers, however, stated that the swirl was still clearly visible when the first depth bomb entered the water.  As swirls do not remain much longer than 20 or 30 seconds following submergence, it may well be that the delay which was both clocked and estimated was less than supposed.  The gun camera photographs to be forwarded later may, as the squadron commander comments, shed some light on this discrepancy.
  
 
 
 
    4.   The report of this action was complete and well prepared.  The comments of the squadron commander were both well-considered and pertinent.  Particularly to be noted are his remarks concerning the lack of training facilities and material in this area.
  
 
 
 
    5.   In view of the fact that it is impossible to reconstruct this attack, and as no competent evidence of damage was observed, it is considered that the submarine received no damage as a result of this attack.
  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
- 2 -