def invalid_fg_vsby(s, v):
    """Checks if visibility is inconsistent with FG"""
    # NWSI 10-813, 1.2.6
    if len(s) == 2 or s.startswith('FZ'):
        if v > 0.6:
            return True
    elif s.startswith('MI'):
        if v < 0.6:
            return True
    return False