It is critical in certain altitudes and heat combination. Specifically obviously with heavier people. If someone is 150-175 ish that is considered a normal additional payload. Time of day, landing zone all play into it. Altitude where accident was sits about 5200 feet in the heat of the day. Just the worst case possible plus need to have well over hour of fuel on board for flight to Vegas. Extreme heat days we have had helicopters not able to lift for high altitude calls. It has improved but still a factor in the summer.I've been racing for 25 years and I just learned here that a helicopter needs my weight to launch? How the hell is that not required on the entry form?
In some areas if they have a runway, they can use the long straight away to fly low, build speed and eventually generate lift. That is what they had to do in landing here. Rather than a hover and drop it on the spot they did a long approach above the course to the ground.
However to your question, with a multitude of drivers in every vehicle, and zero desire to broadcast which driver or even team is being flown out, it’s just simpler to get an estimate from the team on scene.
the pilot then goes through his weights, measures, balance and altitude calculations and determined if he can max fuel or needs to keep it close. They have to figure time to scene, time to circle assuming the scene is where they hope it is. Idle time on scene for hot load and transport time to hospital. In this case the helicopter came from Pahrump but would fly to Vegas with the patient, and still need enough fuel to leave hospital and go to north Las Vegas airport for fuel. So many factors come into play. On rare occasions, the medic or equipment is left at a scene to be retrieved later. (I’ve been that medic to be retrieved later).