It breaks my heart to write this. Oscar was loved by many and I feel privileged to have been his friend. He was an exceptional person, warm hearted, caring, humble, generous, and a teacher of life to many of us. Also an incredibly strong climber, strong in the mountains, and was among the elite in the Spanish mountain rescue police (Guardia Civil - Unidad Especial del Grupo de Rescate de Montaña).
Oscar's approach to jumping was a steady and conservative progression, always putting in the groundwork. He was quietly determined and did not push hard. Oscar was one of the safest jumpers I knew.
He was motivated to fly wingsuits and this year to fly terrain. That he signed on for a Next Level course earlier in the year is testament to his methodical and cautious progression. I was his mentor for wingsuit BASE.
In 2017, Oscar and I opened the jump 'Punta Calva'. At that time he was not ready for terrain flying, but I discovered that this jump has good proximity lines. The exit is not too technical, you then traverse to the left for about 20 seconds over steep terrain, and then make a turn to the right and dive down on the talus. The talus in that part of the mountain is generally steeper than 2:1 with no serious terrain traps. In my opinion its a good jump to start practicing proximity flying, because one can easily disconnect anywhere from the terrain. Last year Oscar made something like 10 to 15 jumps from this exit flying high (no proximity).
This year, Oscar was motivated to start terrain flying. Punta Calva was the obvious choice. He made several flights over what is probably the most straightforward proximity line on the mountain, each flight progressively lower. Oscar was flying with good speed always, and had good control of his suit. He could sustain a glide of more than 3:1 at speed when necessary.
On the day of his accident, we made a jump on Punta Calva in the morning. He followed his normal line, with good speed and stayed more connected with the terrain than previously. It was his best proximity flight and he was super excited about it. We went through his video twice and I was stoked for him. It looked good to me, he flew a tighter line than before, but it wasn't too close and he was fast and in control.
We packed and rested and then decided to go for an evening jump, after a thunderstorm. Its a 2 hour hike, but we both felt physically fine at the exit, no fatigue, no stress. It was a little cold and a light breeze less than 5km/hr. The air was clear apart from some small clouds at the very end of the traverse section of the flight where we normally turn right and start diving. In other words, the conditions were perfect for a high flight straight out to the landing, but less than perfect for flying the proximity line. The plan was for Oscar to jump first, and then me once he had landed. After 15 minutes waiting, the clouds were still there on the talus and Oscar offered for me to go first if I wanted. I was getting cold and the clouds didn't bother me too much so I agreed, and jumped.
I flew my line, the clouds were thin and did not get in my way. I felt no significant turbulence. My flight over the talus took me to a different landing field than the one that Oscar was using. 10 minutes after I landed those small clouds were still there on the talus, and half an hour later they were gone.
We called the rescue 1 hour after I landed, after trying to reach Oscar on his phone and checking his landing area.
We don't know when Oscar jumped and at this stage we don't have his camera or Flysight. It appears that he impacted some tall trees on a small ridge / shoulder towards the end of the traverse section of the flight, and came to rest 100 metres further on. His canopy was out, slider up, brakes stowed... probably out due to impact. He died instantly.
Its not clear to us why he crashed there, because there is an easy escape to the right. Possible factors are...
1. Having a bad start or poor glide and being lower there than he was expecting, but still trying to follow the line that he aced in the morning.
2. Clouds.
3. Some other misjudgement.
In hindsight there are so many things I wish I had said. Would they have made a difference, maybe yes maybe no. I want to go back to that morning jump and say, "Wow Oscar that looked really good. Now don't get too excited, take a step back, be safer, fly higher." I accept that I had a motivating influence on Oscar's flying and I feel terrible for it.
Buen vuelo amigo, siempre.
David.

UPDATE
We found Oscar's GoPro and Flysight. It appears he did not turn on his Flysight for this jump. From his video, we see a normal start, then slower than normal flight. His impact is 21 seconds into the flight into the top of 3 tall pine trees growing on a small shoulder of a cliff. He could have flown safely to the right of the trees if he wanted. He tumbled 30 to 50 metres to the base of the cliff. Clouds were not a factor.
Oscar was flying the same line as his morning jump but lower and slower. He was 19 seconds to reach the same trees in the morning. My opinion is that he was flying too slowly and without energy. He seemed to be lining up to buzz those trees from a long way back (at least the last 10 seconds of his flight), and then in the last second he lost his flight, was unable to 'pop' over the trees, and too late to turn right.
I believe Oscar was so focussed on trying to repeat his morning jump that he didn't pay attention to how this flight was going differently.
What can we learn (nothing new really)...
1. Always fly with speed and energy when close to the ground. If you can't, then go for plan B.
2. Don't aim to fly over something. If you want to buzz something you need to be coming down like an eagle in full attack, not just flying lazily towards it.
3. Don't be so focussed on flying the line that you lose your awareness.
The sad thing is that Oscar knew all this before his last jump.