public boolean valid() {
    if (! super.valid()) return false ;
    if (driven != null) {
      if (driven.destroyed()) return false ;
      if (! driven.canPilot(actor)) return false ;
    }
    //
    //  TODO:  Put the passenger-delivery schtick into a different class.  It's
    //  making a mess of things here.
    if (passenger != null) return true ;
    if (stage < STAGE_RETURN && available(actor).length == 0) {
      if (driven != null) { stage = STAGE_RETURN ; return true ; }
      ///I.say("Nothing available!") ;
      return false ;
    }
    return true ;
  }