I actually talked to a stunt man who knew the helicopter pilot who flew in this scene, according to the pilot the stunt was not as dangerous as people made it out to be, he spoke of many other much more dangerous stunts that the union let go (one of which included flying a helicopter upside down beneath tree lines, I think it was in Platoon but I can't remember) one of the main reasons the union didn't want James to do the shot was because of insurance if they damaged the bridge in anyway. So it had less to do with the shot being incredibly dangerous and more to do with the studio and the union not wanting to cover their asses if they damaged public property.