ANALYSIS OF ANTI-SUBMARINE ACTION BY AIRCRAFT.
	Unit.     VB-129        Unit Report No.      1        Incident No. 3893
	Base of Operations: Bahia, Brazil             Aircraft No.      74-P-6
	Squadron No. of Aircraft:      129-B-9
	Aircraft Type:       PV-1
	Aircraft Commander:      Lt. Comdr. Thomas D. Davies, USN.
	Location of Attack: Latitude            11-46 S
	Longitude         34-33 W
	Date:    July 30, 1943 .            Time:      1410            Zone:      Plus 3
	1.      WEATHER
	Scattered clouds, base 2300 feet. Wind 12 knots from 1600. Visibility 30 miles. Sea medium swells.
	2.      DEPTH OF WATER
	1800 fathoms.
	3.      MISSION
	Sweep ahead of convoy.
	4.      APPROACH AND CONTACT
	(a) While flying at 2300 feet altitude just under base of scattered clouds, a visual contact was obtained on a fully surfaced submarine bearing 200 forward of the port beam, distance 15 miles. The submarine was on course 2400 (T) speed 10 knots.
	(b) Approach was commenced immediately, taking advantage of available cloud cover. The submarine commenced a turn toward the approaching plane immediately upon sighting (apparently a mutual sighting). At range of 4 miles the submarine opened fire on the plane. Sighting shots from the planes guns were made at range of 1 mile. The submarine's C/T was then put under concentrated fire. Gunners had been cleared from their platforms when the plane passed over the target.
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	5.      ATTACK
	(a) Passing over the fully surfaced submarine, 4 Mk 47 depth bombs with hydrostatic fuses set to function at 25 feet depth, were released at 290 knots airspeed, altitude 50 feet. The bombs were released in train, spaced by intervalometer at 75 feet. Target angle was 2700.
	(b) During the approach and attack 800 rounds of .50 cal. ammunition were expended by the bow and turret guns.
	6.      REPORTED POSITION OF EXPLOSIONS
	The positions of the explosions, as stated in the report, were: Number one bomb exploded about fifty feet short; number two apparently hit submarine and did not explode; number three about 110 feet over; number four, 195 feet over.
	7.      REPORTED EVIDENCE OF DAMAGE
	After the submarine had moved forward a distance of approximately 300 yards, losing headway, a second explosion was observed midway between the conning tower and stern, throwing up a geyser of water about 200 feet in the air. Following this explosion the submarine submerged on an even keel moving slowly ahead. Large air bubbles and oil rising to the surface indicated some headway and change of course to starboard. The submarine broached during this turn then appeared to settle stern first. More bubbles indicated continued forward movement. Shortly after these bubbles were emitted, the stern emerged and assumed an extreme angle exposing rudder and screws. After remaining in this attitude for about 3 minutes, with no headway and screws idle, the submarine settled out of sight, leaving oil slick and air bubbles which persisted for about 15 minutes.
	8.      SUBSEQUENT ACTIONS OF AIRCRAFT
	(a) The aircraft remained in the vicinity of the attack for two hours and twenty minutes after the attack when, having reached its PLE, it returned to base.
	(b) Four other aircraft conducted baiting and holddown tactics until 1830P when adverse weather prevented further flying.
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	9.      ANALYSIS OF ATTACK
	(a) Photographs forwarded with the report of the attack show the stern of the submarine protruding from the surface at an extreme angle, the rudder and possibly the screws visible, while the conning tower is still beneath the surface. This indicates that the submarine was out of control due either to the effects of the initial explosions or to the second explosion which was reported to have been observed.
	(b) This submarine suffered further attack in the ensuing twelve days and was scuttled shortly after her crew had been transferred to other submarines, one of which was sunk. It was ascertained from interrogation of survivors that as a result of this attack the submarine's tanks were seriously damaged. This substantiates the opinion that the submarine was out of control when the above mentioned photographs were taken.
	10.    COMMENTS
	(a) This attack was executed with considerable skill, especially in the handling of the bow and turret guns. The sighting-in burst, range estimate, and accuracy of fire are clearly indicative of proper training. Information from survivors confirm this accuracy by attributing two deaths in the conning tower to machine gun fire during this attack.
	(b) The report of this action was quite complete and very well prepared. It was accompanied by an excellent series of photographs and track chart.
	Enclosure (A) to
	Cominch ser. 03698
	dated 26 October, 1943.
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