At the age of 48. Why? As the skateboard legend says in the above video, "Because I feel like I can." His son Spencer, who was there to witness Hawk's first 900 in 1999, was there to witness this attempt as well.
Does dad nail it at an age where most guys start to throw out their backs by simply sneezing? Watch and find out. Then go out and try whatever it is you think you're too old to do. As Hawk says before his attempt, "Keep going 'til the wheels fall off, I guess."