This paper is partially a literature study of human error and interruptions and partially an investigation of pilots and Air Traffic Control. The aim of the investigation was to find out where interruptions occur and how to reduce or eliminate them. The objective of this paper was to investigate what type of interruptions pilots and ATC deals with and during which phases they occur. The paper has revealed that private pilots causes more interruptions for ATC personnel than commercial pilots. The cause for this is probably the less experienced private pilot and the fact that Swedish is used before English by private pilots in communication with ATC. Further on the paper has revealed that communication with ATC causes most interruptions for commercial pilots and that interruptions caused by flight attendants have decreased. The latter is probably caused by the Crew Resource Managment courses. It is when using approach checklist most interruptions occur and there are three different techniques for memorizing the item on the checklist: "Thumb in track", callout "Hold at item..." or simply just memorize present item. The latter technique is not to be recommended due to the limited resources of the human working memory