Absolutely loved this game. I used to try and fly an F4 Phantom through the canyon at top speed. My brother created a short film "Attack of the Killer Christmas Trees". Endless fun.
Archive link: https://armknechted.com/sicentral/newpage/SIArchive.html
Given the technicalities of the stunt, I rather suspect you were successful (no crash), or not successful (did crash). "Somewhat successful", seems very - I don't know - 'corporate'..."The number of deaths do not reflect the overall success of the mission, which managed to gather substantial information regarding the cause of the deaths".