The
Crash TV Ski Jump is located on
Big Surf Island near the 3-way intersection of Pitt Av, Grange Hill and Maguire Rd, and you will want to use the
Carson Dust Storm vehicle, under the
Big Surf Island Cars tab.
Once you locate the ski jump in the construction area marked by a large sign, you will want to run up the path using boost the entire time and making sure you don't hit the sides. If done correctly, you will get 4.52 seconds of airtime; shown in the bottom left corner of the screen. If unsuccessful, just try again.
NOTE: For me, it actually unlocked with only 4.34 seconds of airtime.