Well, I'll expand a bit on my cryptic remarks above - spoilers for Sharkerbob's story. (By the way, what do you mean "poser"? There's no entry requirements here.)
Particularly good things: Solid opening, made me wonder what was going on, which was then addressed in terms of the bridge and the gorge. I could envision it. Interesting use of the disability, with the robotic arms. So nice use of the theme. Good description all through, particularly in terms of movement.
Possible improvements: At first read, I thought the static meant his comlink was busted too, not that he was out of range. There wasn't really an element of immediacy for me - sure it would ultimately be dark, but would no one be looking for him? There were no wild animals or anything. The ending also came a bit out of nowhere - he seemed to be consistently below where he needed to be, then time skip. I'm pretty sure the issue you had in all cases was running up against the word limit. A possible adjustment there would be make sure everything advances the story as much as possible, omitting details we don't need (his sizing up the gorge and the fifty feet bit feels unnecessary; or how it took a half minute to secure his pack). Even the removing his boots thing could be dropped as it didn't lead anywhere - alternatively, make it the very thing he needed, to avoid the time skip (or to move it earlier).
@GeneralRincewind: Thank you! That's actually terribly reassuring this week, seeing as none of the 30+ people who investigated Part 1 of my recent serial have given Part 2 a try.
@Tartra: Ditto, with the added remark that I don't think anyone's ever told me my writing has had the feels effect on them that way... so, yeah, wow. Thanks.