What went wrong with Apollo 15 astronaut Al Worden's seat when he was all alone, circularizing?

Question

The X article NASA shock: Apollo 15 astronaut's Moon landing confession - 'Can't do anything to me now' says "NASA astronaut Alfred "Al" Worden dropped an astonishing Apollo 15 confession, claiming NASA "can't do anything" to him after 45 years":

The astronaut told MIT he has kept the incredible story a secret for 45 years.

Mr Worden said: “When I fired the engine to circularise, and I forget how many feet per second I had to add, instead of looking at the instrument panel I was suddenly looking out the left window.

“Because when I ignited the engine, that couch because of Newton went like this and now I’m looking out the side window.

“You talk about freaked out. I was really freaked because I could not reach a single control.

“So thank God the computer worked and it stopped at the right time and I was ok.

“I never told anyone that, only 45 years later I dare and even try mention that. They can’t do anything to me now.”

According to Mr Worden, the three seats in the Apollo Command Module were mounted on swivelled shock absorbers.

When the astronaut fired the spacecraft’s engines to hit a stable orbit around the Moon, he was turned away from the Command Module’s console.

“And so you adjust all that string of material all the way across there and you can kind of get the couches from bouncing back and forth because you put a little pressure on the pressure pads.

“Well, the centre couch was out. The shock absorber is on a swivel.”

Question(s):

1. What happened here? I can't understand the explanation. Starting the engine and adding some amount of acceleration caused the seat to rotate, and somehow it was impossible for Worden to see some display or some instruction, as well as impossible rotate the seat back?
2. Is this a design error? Across all Apollo lunar missions? Was it ever corrected? Or was it something akin to "pilot error"?
3. Has something similar happened on other Apollo missions?

Answer 1

After having gone through the Apollo Operations Handbook a gazillion times, I think I know what may have happened.

First, to establish the situation, refer to figures 1-12 and 1-13 of the Handbook for nomenclature and orientations.

Excerpt of Figure 1-12 from Apollo Operations Handbook

Figure 1-13 from Apollo Operations Handbook

• In the article, Worden is explaining he's alone, Scott and Irwin being on their way to land. There's one circularisation burn after that, at T+101:39 that he will need to do by himself. The center couch is stowed by then (to facilitate LM ingress, per the Handbook p. 1-24).
• With the center couch stowed, and since the flight controls, including the computer interface, are on the left-hand (CDR) side of the CM, Worden will be sitting in the left couch.
• In video accompanying the article, Worden is illustrating the motion of the seat. It is clearly a rotation in the X-Z plane, but it is unclear if he's indicating a rotation around the hip, head or foot.

Figure 1-14 of the handbook shows the following overview of a single couch:

Excerpt of Figure 1-14 from Apollo Operations Handbook

The couch was connected to the CM structure by two YY struts connected to the outer wall of the of the module and large beams that connect the foot XX struts, head XX struts and ZZ struts. The couch was furthermore connected to the head beam with two pins. See also Figure 1-19 of the Handbook.

The item labeled "YY Strut Handle" is presumably the "swivelled shock absorber" that Worden refers to in the video. Figure 1-21 of the Handbook shows the YY strut in detail.

My theory of what happened

In order for Worden to "see out the left window", he would need to be sitting in the left seat and then rotate backwards around the Y-axis going through the YY-struts. This would normally not be possible, because the head bracket would collide with the head beam during this rotation. In any case, that bracket should be secured to the head beam with the two pins.

However, do note that there is a hinge at the shoulder. This hinge can be unlocked (see Figure 1-16), allowing the head bracket to be folded and allowing the whole seat to rotate freely around the hip.

I'm hypothesising that during LM preparations and undocking (recall that they had a problem separating the LM) the seat was disconnected to get better access to the hatch, and that they forgot to lock the shoulder hinge and head bracket back in place. When Worden fired the SPS, Newton did his thing and rotated him backwards about 90 degrees, and he looked out the window.