It was a forseeable accident.
I trained in that aerodrome (LESB Son Bonet) and it belongs to NON controlled airspace. West of LESB is the ULM aerodrome (Binissalem, also NON controlled) and south of that aerodrome is Palma de Mallorca airport (LEPA controlled airspace).
In the VFR charts there are VFR corridors which pilots should use while entering and leaving airspace (locals use north of a highway to arriving traffic and south to departing traffic -which coincides with the VFR corridor, and it's safer, yet NON standard-) and there's a published procedure in which you must communicate through 123.500 (much like a CTAF) intentions. The problem is that whenever you depart LESB (Bell helicopter from Rotorflug operated there) you need to activate your VFR FPL via LEPA TWR and may even navigate through non controlled airspace in any frecuency except the one you MUST USE. The ULM's operating at Binissalem aerodrome SHOULD use 123.500 frequency.
Also, LESB has been seeing a steady increment and flow of general aviation traffic as it's an aerodrome with cheaper fees to operate in instead of flying to LEPA.
So, you have a non controlled airspace, with a CTAF that some pilots don't use, 2 aerodromes (one with years of increasing traffic), VFR corridors which don't specify which way should a pilot use if departing or arriving at that airspace and not even an AFIS/FIS.
I trained there from 2016 to 2018 and found myself a helicopter and a twin piston ahead. If authorities investigate SMS reports at LESB they will have a field day.
Again, a foreseeable accident.
RIP to those involved.