A postflight report by the MSC Crew Systems Divison (CSD) on the performance of equipment it supplied for the mission, the Lunar Equipment Conveyor (LEC) is listed as 'LEC - Waist Tether Kit'.
The Apollo 11 Final Lunar Surface Operation Plan contains several references to use of the LEC as a 'safety tether', particularly the two extracts that follow:
The nominal timeline does not include any reference to Buzz using the LEC as a tether during his climb down the ladder, nor to its use by either crewman for the climb back up to the cabin at the end of the EVA. It seems likely that, based on pre-flight simulations, they were confident that, once Neil demonstrated that the ladder was not going to be a problem, a safety tether would no longer be necessary for this aspect of the mission.
On Apollo 11 - but not any of the other missions - the LM crew attached carabiners (aka 'snap locks' or, simply, 'hooks') to their tiedown straps. Buzz's can be seen in a detail from training photo KSC-69PC-362
and, also, in a detail from lunar surface photo AS11-40- 5873.
Neil's carabiner can be seen in a detail from training photo 69-H-669
and, as noted by Andy Chaikin, in frames from the Apollo 11 TV at the time Neil was moving the TV away from the LM.
These carabiners seem to have been intended to secure gear, as illustrated in KSC-69PC-362 (above) where Buzz has the carabiner fixed to the camera handle. Indeed, there are a number of training photos showing either Neil or Buzz with the carabiner attached to the camera handle but none indicating use with other pieces of equipment other than the camera or the LEC (below).
Neil and Buzz attached the carabiners to their tiedown straps early in the EVA preparations, as per LM Lunar Surface Checklist page Sur-26. After configuring the 16-mm Data Acquisition Camera and the 60-mm and 80-mm Hasselblads, the next task was:
A discussion and pre-flight, pre-stowage photos of the package containing the Lunar Equipment Conveyor and Tethers is linked here. Of relevance here are the two carabiners (hooks), one stowed upright at each end of the bag in photo S69-37998, which they removed from the LEC/TTHR package and attached to the tiedown straps. All of this was done at some point between 106:11:14, when Neil reported that they were starting the EVA Preps, and 106:49:07, when Buzz reported they had reached the top of page Sur-27.
To complete this set of tasks, they
The PLSS Upper Donning Station Pin, known also as a 'handhold' on later missions, was inset in the cabin ceiling and is the yellow rod in Apollo 15 pre-flight photo S71-40733. In this case, the 'hooks' to be attached to the 60mm Hasselblad are carabiners on either end of the LEC strap, as shown in a labeled version of S69-37994.
After donning the PLSSs, completing other EVA Prep tasks, depressurizing the cabin, and opening the hatch, at 109:15:55 they attached the carabiner on Neil's tiedown strap to the 'end loop' of the LEC.
As indicated previously, Buzz would continue to play out the LEC and monitor Neil's descent and first steps on the surface.
We don't have any pictures of the LEC in use as a tether during most of Neil's climb down the ladder because the settings Buzz had on the window-mounted 16mm camera were not appropriate to shadow photography. However, just before Neil's statement at 109:24:14 that he was about the step off the footpad, Buzz changed the camera settings. The filmed image brightens and we get quite a bit of detail, including the LEC. We can also see reflections of what appear to be parts of Buzz's suit as he monitors Neil's activities out the window. Ken Glover has grabbed a frame from the 16-mm film.
Note that there isn't much sag in the LEC, which suggests that Buzz is playing out just enough of the LEC to give Neil freedom of movement and is ready to help Neil brake any slip or fall as implied by the phrase 'use as a safety tether' in the Ops Plan. Unfortunately, we have been unable to confirm this supposition with either Neil or Buzz. In a 14 December 2004 e-mail, Neil wrote "You make a persuasive case about the LEC, but I cannot remember the detail well enough to confirm or dissent."
Training photo S69-32246 shows Neil on the footpad with his carabiner attached to the LEC 'end loop'. The LEC is hanging loosely on the ladder, undoubtedly because there is no one in the simulator cabin. Ulli Lotzmann notes that in, the film record of what was probably a typical training session for his first few minutes on the surface, Neil gets ready by stepping into the footpad and attaching his carabiner to the 'end loop'. Neil then steps off the footpad and the training session proceeds onward from that point in the timeline.
Returning to the actual mission, once Neil is on the footpad and the TV signal switches to Honeysuckle at about 109:23:48, the LEC can be seen very faintly against the black sky and, as in the 16mm record, does not appear to be sagging. The LEC also becomes evident against the sunlight lunar surface once Neil is off the footpad. Andrew Chaikin has captured three TV frames
which show the LEC, the carabiner/tiedown, and the end loop. If my interpretation is correct, he had the carabiner attached to the LEC strap just above the end loop, rather than on the end loop, itself, a trivial detail.
After finishing his brief period of Environmental Familiarization, at about 109:26:16 Neil detaches the LEC from the carabiner and gets ready to transfer of the Hasselblad camera down from the camera.
Finally, Ulli Lotzmann notes that, for Apollo 12 and the later missions, the LEC was used solely for equipment transfer, as implied by the following extract from page 31 of the Apollo 12 Final Lunar Surface Procedures volume.
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