As a pilot who has been flying EMS for the last 18+ years and whose aircraft has had a Radar Altimeter (here in NC it's a state requirement), I will vouch for it's usefulness. On one occasion it proved to be worth it's weight in gold when one of my pilots succumbed to what's commonly called a "black hole approach" coming into a landing area over water. Focused on the landing area he descended to 200 feet when he 'thought' he was at about 500 when the radar altimeter "alarmed" and warned him of his error.
It is also a very valuable tool when you have gone single pilot inadvertent IMC and have to make that ILS approach to set up for DH. But it is not terrain avoidance equipment... and frankly speaking of which,the same terrain avoidance equipment that works so well in airliners is totally useless to us. The altitudes that are 'death' to them is where we make our living.
The South Padre accident is the one I've read about over and over and over in the last 30 years in air ambulance helicopter flying. It is were the problem is. I am willing to bet that all the equipment necessary for at least basic instrument flight were present in that helicopter. I am even going to assume the pilot has an Instrument rating. And I'll bet the ranch that pilot was not instrument current.
One extremely high time airline captain and widely experienced general aviation pilot has written that he can perceive a significant degradation in his instrument flying skills after a few weeks away from flying instruments. Many pilots in the Air Ambulance industry have not been instrument current in years or even decades!
Two nearby vendor system allow 15 minutes of simulated instrument flying per pilot per year during daylight using foggles (if one peek is worth a thousand cross-checks, what is constant peeks worth?), and that's it. In a conversation with one of their guys, a retired Navy helo pilot, I was told the last time he was instrument current was when he was in the Navy 12 years ago!? And this is flying in a coastal environment where night time inadvertent IMC is just a fact of life. It's not if, it's when .
I cannot believe that the FAA has not mandated instrument currency requirements for pilots of air ambulance aircraft operated at night given the large number of accidents that read just like this South Padre accident. Even though we are not an IFR operation, I would not consider allowing one of my pilots to fly night VFR in our area if he were not IFR current.
The problem is not equipment. The problem is not pilots of and in themselves. The problem is currency training and operators who say "it's too expensive"..., and the FAA who won't mandate currency.