Ok guys you both have me convinced there is a problem with attack vulnerabilities on both systems, but realistically how much of problem is it? Let assume the fool doing it does not get caught rapidly, is the cost involved in keeping VORs a big enough investment considering the risk of GPS interference? I mean when I was born you still had steam gauges in your 707s now it's rare to see an airliner that is not glass and people had their trepidation about that, so really is eliminating VORs and forcing GPS that big of risk? From the cost and risk standpoint mind you.