Check this from an article from Michener's notes on "Bridges" from the Library of Congress:
Soon after his arrival aboard Valley Forge in January 1952, Michener witnessed what was to become the central theme for his book. Early on 8 February, Rear Admiral John Perry, Commander Carrier Division 1, and his staff were alerted to engage in a possible rescue attempt of an escaped prisoner of war (POW) pilot, Lieutenant (jg) Harry Ettinger of Composite Squadron (VC) 35, who had been shot down in December 1951. Friendly guerilla forces removed the ailing Ettinger from a POW camp and took him to the Wonsan area, where they contacted U.S. intelligence units for a possible rescue.
It was a routine job for Chief (AP) Duane Thorin and Petty Officer Ernest Crawford, who manned the duty HO3S-1 helicopter aboard Rochester (CA 124) that morning. A member of the intelligence group replaced Crawford, and the HO3S-1 was loaded with supplies for delivery to agents on the ground. As Ettinger climbed aboard at the rendezvous point, the helicopter crashed. Meanwhile, the rescue combat air patrol (RESCAP) aircraft overhead were under heavy fire. Lt. John P. McKenna of VC-3 was fatally shot down in an F4U-5N Corsair, and four AD Skyraiders were forced to land due to battle damage. An HO3S-1 from Greer County (LST 799) was launched to try to reach Thorin, Ettinger and the crewman but was riddled with bullets. After two attempts the stricken helicopter departed the scene, safely landing aboard St. Paul (CA 73).
An hour later, four AD-3s from Fighter Squadron (VF) 194 and two F4Us from VF-653 led by Lieutenant Commander Robert Schreiber, CO of VF-194, were scheduled to hit three railroad bridges on the Kowon-Yangdok-Samdong-ni rail line. Aerial reconnaissance photographs from F9F Panther photo planes showed that the targeted stone bridges lay in a deep valley with heavily defended guns atop surrounding hills, which required a hit-and-run attack.......
For many years, Cdr. Paul N. Gray, CO of Attack Squadron 54 aboard Essex, was rumored to be the basis for The Bridges at Toko-ri’s central character, “Brubaker.” However, the author’s notes reveal that the character was patterned after Lieutenant Donald S. Brubaker of VF-194 aboard Valley Forge, whom Michener interviewed on 5 December 1951 and, like his literary counterpart, was recalled to active duty as a Naval Reserve pilot. The final death scene, however, was taken from the above-mentioned incident of Brubaker’s squadron mate, Ens. Broomhead.
Some room for confusion.