16-57 403, 16-57 403

Veteran served in the U.S. Navy, Feb 1964–May 1972, as a radar intercept officer aboard carriers U.S.S. Constellation and U.S.S. Coral Sea.
Veteran submitted flight log entries and buddy statements showing flights to "DAG" (contended to be Da Nang) on Oct 18, Nov 15, and Nov 26, 1967; co-pilot’s partial log corroborates two flights.
JSRRC responses (Feb and Sept 2016) reported Coral Sea command history and deck logs did not record personnel landing at Da Nang.
Private medical records establish a current diagnosis of prostate cancer.
Board found the Veteran competent and credible to report stepping onto Vietnamese land, resolved reasonable doubt in his favor, concluded he served in the Republic of Vietnam during the presumptive period, and therefore presumed herbicide exposure.

Issue	Plaintiff's Argument	Defendant's Argument	Held
Service connection for prostate cancer based on presumptive herbicide exposure	Veteran asserts he landed at Da Nang on three specific dates; submitted flight logs, co‑pilot log, and buddy statements to show presence in Vietnam	JSRRC/RO: ship command history and deck logs do not show Coral Sea personnel landing at Da Nang	Granted — Board found lay evidence credible, resolved reasonable doubt in veteran’s favor, and awarded service connection (herbicide exposure presumed)
Competency/credibility of lay evidence to establish presence in Vietnam	Lay testimony and contemporaneous flight logs are competent and corroborated by others	Administrative record (deck logs) lacks entries corroborating landings	Board found veteran competent and credible based on specificity, corroboration, and consistency; credited lay evidence

Layno v. Brown, 6 Vet. App. 465 (1994) (lay evidence may be competent to establish certain facts, including presence in a combat zone, when within a veteran’s personal knowledge)