Okay after watching several YouTube videos from some of the people running 107 test preparations I have become confused. If you are flying under part 107 and in class G airspace and are within 5 miles of a private Airport which is also in class g airspace, do you contact the airport when you are flying under 107 as a requirement of the law, or is this just a courtesy call? it appears that if you are flying as a hobbyist you must contact the airport to comply with the law.