I'm a few years late with this, but I wanted to post this because I found this thread in a search, and I wanted to post this for any future lurkers who find this thread by searching for a walkthrough for this mission or something. I started playing 911:FR again after a long time, purely for the nostalgia, lol.
(Thank you for the video, by the way, @itchboy, very helpful!)
Anyway, in the video linked above, the author used the USCG helicopter to pick up and transport victims. The latest version of the LA Mod gives you access to the helicopter for this mission, but the only personnel you can put on board is an LAFD diver. The coast guard worker has to rappel down and strap the patient into the basket - but the game won't let you put him on board, which is why the helicopter isn't able to pick up anyone, making it useless.
However, I found a way to fix this! This involves editing your game files, but all you need is Notepad (or VSCode), and you're changing one line that will allow the USCG worker to board the USCG helicopter.
Is this cheating? Maybe. But in what world would the Coast Guard lend a chopper to the LAFD, and not send any USCG personnel with it? In fact, LAFD themselves have rescue helicopters in real life with the capability to rappel rescue workers and save victims that are trapped. So I see it as fixing a bug - anyway, moving on...
The file you need to edit is at the following path:
<path to game folder>\Mods\Los Angeles Mod v2.1\Units\Personnel\TEC\020uscgrescue\unit.xml
This file specifies info about the USCG worker, including what missions he can be used on. Line 3 looks like this:
<missions value="8 5 17 12 14 7 19 10 6 18 16 11 20 23 24 25 32">
The mission ID's can be found in "Specs\campaign.xml" under the LA Mod folder. In that file, you'll see that index 13 corresponds to the freeway bridge mission (confirmed by watching mission13.mpg under the Video folder in the base game directory)
TL;DR - You just need to add "13" in the middle of this string, between 12 and 14, like so...
(Path to file for those that didn't read above: Mods\Los Angeles Mod v2.1\Units\Personnel\TEC\020uscgrescue\unit.xml)
<missions value="8 5 17 12 13 14 7 19 10 6 18 16 11 20 23 24 25 32">
If you open the unit.xml file for the USCG helicopter, you'll see it's available in this mission, but if you can't put a USCG engineer onboard, then what's the point?
I just quickly tested this change, and it fixes the problem! Now the USCG helicopter can be used to pick up injured people! You'll still need a boat and divers in the water to pick up the two people floating down the river (which is something I think the heli should be able to do...), but that's ok, because you need the divers to find the submerged vehicles anyway.
Also, here's a useful bit of info I found in the script for this mission - the bridge collapse is triggered by the pontoon bridge vehicle being deployed. The game starts a timer after the bridge is either started or completed (not sure which) - from what I can tell, the game gives you 5 minutes from that point before the bridge collapses. So like you'll see in that video, if you wait to the very end to deploy the pontoon bridge, you can easily use your helicopters (air ambulance + USCG helo) to deal with the victims on the other side of the bridge! (What city has artificial bridge trucks just sitting around, anyway?! Just pretend the bridge takes several hours to construct, LOL!)
Now, the video also shows the author deploying "large ambulances" to transport victims. This unit does not seem to be part of the latest version of the LA Mod (or maybe it's a Deluxe vehicle, I don't know), which is unfortunate. Now you could use the same procedure I just showed you to enable use of the Mass Casualty Unit, buuut, I would probably put that in the "cheating" bucket, so take that as you will. And I mean, let's be real - when it comes to this mission, you don't get a lot of room to work anyway, so I probably wouldn't want to waste money and parking space to deploy an MCU. You're better off just sending a whole bunch of paramedics in a truck or SUV, and then sending the truck home, like the video author did.
Anyway, I hope this helps anyone who finds this thread in the future!