You don’t need the direction however, just the magnitude of the acceleration in 3D prior to impact. If it is within the ballpark of 9.8 m/s prior to the massive impulse spike caused by it hitting the ground you can disregard the spike as a drop. If the phone is at a resting state/a state with very little acceleration prior to impact (ie a phone on a dash in a car that immediately hits a wall) or has a large magnitude of deceleration (driver hits the breaks quickly before impact) than you can diagnose that as a crash. You don’t need direction of acceleration if you just simplify the problem