I despise the Kennedys, but the mission Joe Jr died on seems to have been pretty high risk:
http://en.wikipedia.org/wiki/Operation_Aphrodite#Mission_theory
During World War I the Navy let a contract for an “aerial torpedo.” A company owned by Lawrence Sperry actually hit a target from 90 miles away with fragile wood and fabric biplanes. Some of the usual tomfoolery of military contracting kept them from getting the contract, and eventually the Navy pretty much gave up on the whole idea. But a young Army officer named Hap Arnold had been allowed to witness the tests, and he was impressed.
Thirty years later and Arnold is the head of the Air Force. England is littered with obsolete model B-17s. Remembering the earlier Navy tests, he comes up with the idea of loading these obsolete aircraft up with bombs and flying them into targets to heavily defended to attack conventionally.
Through a combination of not having the correct people there, and lack of interest in general, it was a fiasco. The biggest problem was bomb arming. They had the right idea to take off without the bombs armed, and then arm them in flight. But many times when they tried to arm the bombs, the aircraft blew up.
In desperation Arnold got in touch with the Navy, thinking they still had data or expertise from the World War I test that might be of use. Instead of joining the effort, the Navy basically went into competition with the Army. They also had obsolete B-24s and figured to show up the Army. Kennedy was part of the Navy program and had nothing to do with any of the aircraft mentioned in the wiki article.
The Navy also had what would later prove the correct idea. They had a radio controlled bomb arming system. The crew was to jump out, and be safely away, before the command to arm the bombs was given. The sharpest technical guy in the outfit was assigned to be Kennedy's co-pilot.
While this fellow was really sharp technically, he had no confidence in the radio controlled system. Since he didn't trust the radio part, he took a wooden stick that was used to hold open a hatch and jammed it between the bomb arming mechanism and the bombs. His thinking was that this would keep a stray radio signal from arming the bombs accidentally. What subsequent tests proved was that with this piece of wood jammed into place, it forced the mechanism back too far. The motor that moved the mechanism was energized trying to push it back into the correct place. After about three hours the motor would catch fire and cause the bombs to explode.
There was some confusion the morning of the flight and they circled around for about - three hours. They were just about to be given the command to jump when it exploded. If the copilot had gone to the back to remove his stick, he might have noticed the overheated motor and avoided the whole incident.
The system was later tested and found to work fine - as long as you didn't jam a stick into the works. As far as danger goes, the average B-17/B-24 pilot that was heading for Germany would have GLADLY traded places.