This photo provided by Innovative Signs, Inc. in Longwood, Fla., in June 2018, shows a memorial plaque that was dedicated Saturday, June 23, 2018, in Valdez, Alaska. It honors four Alaska Air National Guard members who died in a plane crash while conducting a humanitarian mission following a devastating magnitude 9.2 earthquake which destroyed Valdez in March 1964. (Photo courtesy Innovate Signs, Inc. via AP)
Former Alaska Air National Guard member Chuck Volanti salutes the honor guard at a plaque dedication ceremony Saturday, June 23, 2018, in Valdez, Alaska. The memorial plaque, which Volanti has worked for years to realize, honors four Alaska National Guard members killed in April 1964 while conducting a humanitarian mission after the second most powerful earthquake ever destroyed the town. (David Lienemann/Office of Alaska Gov. Bill Walker via AP)
Alaska Gov. Bill Walker delivers remarks at a plaque dedication ceremony June 23, 2018, in Valdez, Alaska. (David Lienemann/Office of Gov. Bill Walker via AP)
The Alaska Air National Guard honor guard presents colors at a plaque dedication ceremony Saturday, June 23, 2018, in Valdez, Alaska. The memorial plaque honors four Alaska National Guard members killed in April 1964 while conducting a humanitarian mission after the second most powerful earthquake ever destroyed the town. (David Lienemann/Office of Alaska Gov. Bill Walker via AP)
This undated photo provided by the Alaska National Guard shows Maj. Gen. Thomas P. Carroll, the adjutant general who died with three other men in a plane crash near Valdez, Alaska, on April 25, 1964. On Saturday, June 23, 2018, a memorial plaque for the four men killed on the humanitarian mission was unveiled in Valdez, Alaska. (Photo courtesy Alaska National Guard via AP)
This photo provided by Kenneth Ayers Jr. shows his father, Kenneth Ayers Sr., in his Air Force graduation photo in 1956. The elder Ayers and three other Alaska Air National Guard members died in a plane crash following the 1964 earthquake. A memorial was unveiled June 23, 1964, honoring the four men killed in the crash when conducting a humanitarian mission following the devastating magnitude 9.2 earthquake which destroyed Valdez in March 1964. (Photo courtesy Kenneth Ayers Jr. via AP)
This photo provided by Kenneth Ayers Jr. and taken in 1960 shows his father, Kenneth Ayers Sr., after a successful moose hunt in Alaska. (Photo courtesy Kenneth Ayers Jr. via AP)