It's happened again. Another EMS rescuer has plunged to her death during a hoisting operation.

This one happened April 27 in Texas. Nurse Kristin McClain, 46, somehow became disconnected while ascending to a STAR Flight Airbus Helicopters H145 during the night-time rescue of an injured hiker.

Hoisting in the dark is always a tricky business. Take the case in 2013 of Las Vegas police officer David Vanbuskirk, 36, who perished when he came off the hoist line during another night-time rescue.

Particularly at night, hooking onto the right ring requires extra time and extra care, but mistakes can happen under any conditions. An Air Force report on a fatal 2012 hoisting accident is instructive. In that case, the deceased was being lowered from an HH-60G Pave Hawk.

The report found that he accidentally attached the hoist line to the non-load-bearing plastic D-ring of a tactical vest instead of the load-bearing metal D-ring of his harness. The plastic D ring broke. This accident mirrored a 2009 fatal U.S. Forest Service rappelling accident. In that case, the deceased's J-hook had been attached to a rubber O-ring, rather than to a load-bearing Tri-link.

These accidents are generally preventable if people would just slow down and double-check their equipment. The National SAR Academy Training Manual discusses best practices for helicopter rescues in some detail, including hoisting operations. Particularly instructive is Part 133 of the Federal Aviation Regulations (FARs).

While private-sector aircraft operating in emergencies and public-sector aircraft are exempt from these provisions, they provide a good operational template for all operators. Helicopters with "external human cargo" require the use of twin-engine aircraft with "hover capability with one engine inoperative at that operating weight and altitude."

The regulation also mandates aircraft-to-rescuer communications and the use of an FAA-approved "personnel lifting device" with an emergency release that requires "two distinct actions."

The National SAR Academy recommends the use of positive action "auto-locking hoist hooks" with a latch to guard against accidental opening leading to equipment or line entanglement. The auto-locking hooks also can guard against rollout, which happens when an attachment D-ring moves upward after load relief and rides up against the safety latch of the hoist hook. This reversal can pressure a nonlocking latch to self-release the load. Using the right-sized connectors and keeping them properly oriented during a lift can also help.

Static discharge must also be guarded against when performing a lift. The best way to prevent static shock is to let the hoist cable touch the ground before ground rescuers handle it. The cable should be rolled out and inspected after each use. Cables with any obvious damage should be replaced as should those that have ever been subjected to overload even if they have no apparent damage.

Hoisting is an important and essential component of helicopter rescue capabilities, and it is inherently risky. But that risk can and should be minimized.