Apollo 13's plutonium RTG re-entry into the Tonga Trench: Good shootin' or good luck?

Question

Plutonium powered RTGs are encased to survive re-entry. According to the Wikipedia article on Apollo 13

RTGs were used to power … the scientific experiments left on the Moon by the crews of Apollo … Because the Apollo 13 Moon landing was aborted, its RTG rests in the South Pacific Ocean[6]

The RTG was carried on the LM, which separated from the CM more than an hour before splash down and re-entered on its own about 500 miles uprange from Apollo 13.

Apollo 13's final midcourse correction had addressed the concerns of the Atomic Energy Commission, which wanted the cask containing the plutonium oxide intended for the SNAP-27 RTG to land in a safe place. The impact point was over the Tonga Trench in the Pacific, one of its deepest points, and the cask sank 10 kilometers (6 mi) to the bottom.

Google Earth

https://honeysucklecreek.net/msfn_missions/Apollo_13_mission/a13_re-entry-groundtrack.html dashed red line is Apollo 13 ground track to splashdown

The splashdown of the CM was very accurate: the “miss distance” was 1.85 miles https://en.wikipedia.org/wiki/Splashdown The RTG landed 500 miles away, over the deepest spot I could find in the Tonga Trench. Good shooting, or good luck? The CM can be steered during re-entry, but re-entry and break-up of the LM should be less predictable. How much control did NASA have over the splashdown site of the RTG?

Answer 1

Good shooting.

Chuck Deiterich, lead retrofire officer, was responsible for the impact point.

From Henry S. F. Cooper's book Moonwreck aka Thirteen: The Flight That Failed:

Deiterich, however, insisted that it was important, because the LM carried a metal cask full of radioactive fuel, which had to be aimed so that it landed in deep water. The radioactive fuel had been intended for powering scientific instruments left on the moon, and its cask was the only part of the LM that was strong enough to remain intact during the heat of reentry; it had been designed this way because during a previous mission such a cask, aboard an unmanned satellite, had scattered its radioactive contents through the upper atmosphere, and four years later these could still be detected around the world. Earlier in the Apollo 13 flight, when it had seemed possible that the spacecraft would come down in the Indian Ocean rather than in the Pacific, the Atomic Energy Commission had sent anxious word that the fuel cask would land uncomfortably close to a populated area of Madagascar. Now Deiterich had assured a representative of the A.E.C. who was present that the controllers would see to it that the cask landed in deep water a couple of hundred miles off the coast of New Zealand

(emphasis mine)

later after some unexpected maneuvering

Deiterich was still worrying about the fuel cask, possibly because he felt the gaze of the A.E.C. man on the back of his neck. He rapidly figured out where the cask would come down under the new circumstances, and he was able to assure the A.E.C. representative that it would still come down in deep water.