The incident at Samoa involved an erroneous ILS. If you Google that expression, you'll find lots of information on it. While the original fault was due to a technical error made by the navaid technician/s, an incident could've been avoided by cross-checking DME distance with the nominated GP intercept point and then doing constant comparisons of altitude and DME distance - it isn't hard, even when the DME is not sited with the GP antenna.