Your fall protection gear is inspected, donned properly, connected to appropriate anchorage with clearances figured out, and you confidently set to work. In a moment of inattention, you step close to an edge and the uneven footing causes you to stumble and fall. Next thing you know, you're dangling a few feet above the ground, shocked but unharmed because your fall protection gear worked as designed.

This is the best-case scenario when a fall happens. That's how we hope the story goes, but in reality fall protection planning has to consider additional and sometimes less talked-about hazards. Here are five that should not be overlooked.

1. Swings

A free object falls down when dropped, but a tethered object swings. This is the change of its potential energy to kinetic energy.

When attached to a static anchor, we usually teach that there is a 30 degree "safe zone" in which the worker can move around. Theoretically, a fall within this zone shouldn't produce much of a swing, but outside of that zone a swing is a big potential problem (pun intended). Or, to be more precise, slamming into other objects or the ground as a result of the swinging motion is a big problem.

Retractable lanyards offer freedom of movement around a work site much greater than a traditional shock absorbing lanyard. A worker can draw out a long length of cable to create a large diameter work area. But imagine this scenario: a worker draws a long line from their retractable lanyard as they walk parallel to a platform edge, which is elevated 15 feet. They turn to walk back and stumble, falling from the edge. If they had walked further than the 15 feet from the anchorage point, they're going to hit the ground. If not, there will still be a substantial, energetic swing and probably contact with other objects.

2. Suspension Trauma

A rescue plan needs to be in place to ensure a worker can get down safely if they fall. There isn't much time for coworkers to get together and brainstorm a plan after a fall, because unfortunately some features of human physiology are working against the worker the longer they hang suspended in their fall protection gear.

When your heart pumps blood to your extremities, it returns through the venous system at a low pressure and relies on skeletal muscle movement as a kind of pump. Hanging upright (the way you would when suspended from a fall protection harness) leaves the legs dangling below mostly motionless with compressive pressure on the femoral vessels. With blood progressively pooling in the legs, perfusion of oxygenated blood to the organs lowers and has similar effects to global hypovolemia (blood loss). Left long enough, the subject will faint and eventually die of hypoxemia.

Exactly how long this process takes depends how much the worker weighs, whether the harness was donned properly and fits correctly, and the worker's age and fitness level. Even under ideal conditions we're talking a matter of minutes before symptoms start to appear.

Ultimately, there is no time to lose in rescuing a suspended worker – the faster the better.

(Learn more about Suspension Trauma: The Danger of Fall Arrest Systems.)

3. Post-Rescue Death

When a worker has been suspended for an extended period due to delayed or complicated rescue, they need medical attention. There have been cases where victims of suspension trauma were rescued, removed their harness, and laid down on a stretcher only to die minutes or hours later.

There isn't a clear consensus on exactly what is going on with this phenomenon. As with suspension trauma in general, the physiology is complex and involves the interplay of a number of systems and processes. It might have to do with rhabdomyolysis (muscle breakdown), acidemia (acidic blood), or hyperkalemia (high potassium) in the now-recirculated blood. It might have to do with blood becoming toxic while it was cordoned off in the legs from prolonged oxygen starvation. It may be none of the above.

Whatever the reason, even a small risk of kidney failure is worth a trip to the hospital after a fall. Medical intervention is likely to help get things back in balance.

4. Snaphook Rollout

Under certain circumstances, the lever holding the snaphook closed can come into contact with the D-ring and move in such a way that the hook opens and "rolls out," leaving the worker disconnected. It doesn't take a lot of force for this to occur, and it could either happen in the process of a fall or during normal work activities. Fortunately, equipment in use today includes elements to prevent such an occurrence.

ANSI standard A10.14 lays out some standards for fall protection equipment, specifically including the caribiner/hook that connects to the harness. It requires a locking type snaphook that is designed to prevent rollout from accidentally disengaging the hook - usually requiring the user to depress two levers in order to actually open the gate. Old, worn-out, or damaged equipment may not do this as designed because, for example, the secondary lever spring might be broken. Incompatible gear can also lead to rollout problems.

The previous ANSI standard specified that the gate of a snaphook has to withstand 350 lbs (1.55kN) from the side without significant deformation. That means if the hook just so happens to be in a position where the side of the gate meets the D-ring while falling, it may not withstand the force of that fall. It wasn't really in line with the tensile strength requirement of 5,000 pounds. for the anchorage, lanyard, harness, and hook itself.

The current ANSI/ASSP standard Z359.12 brings this up to date with a 3,600 lbs. requirement for the side of the gate. However, I imagine plenty of snaphooks are in use that aren't compliant with the up-to-date specifications.

5. Falls on the Same Level or Minor Heights

The control strategies for this type of fall have little in common with conventional fall protection. Yet, incident and injury reports usually consider falls from height as a subset of falls in general. "Falls" also includes statistics for things like "fall on same level while sitting" which, believe it or not, resulted in four fatalities in the US in 2017.

Falling on the same level is usually, erroneously captured in hazard assessments as "slips/trips/falls" (those are incidents, actually). The hazards in question often relate to housekeeping and maintenance which also contribute to falls from height. Some of the same general caretaking controls that come from proper hazard assessment should apply to both same-level and fall from height scenarios, so there is some crossover.

The 2017 US Department of Labor statistics also listed 48 fatalities resulted from falls from collapsing structure or equipment, three of which were from six feet or less. I'm speculating here, but I suspect this wasn't all equipment failure, and a good share of those numbers were makeshift ladders, structures not meant for climbing, standing on shelves, and so on.