influenced by the principles of cognitive work analysis (4) . This approach deliberately deviates from the idea behind models such as the Procedure-Oriented Crew model (PROCRU) (5,6) or the Man-Machine Integrated Design and Analysis System (MIDAS) (7-9) that use human operator models which do focus on the constraints of the human operator. It is anticipated that by focusing on the environment of the pilot instead of on the limitations of the pilot himself much simpler models can be achieved to predict pilot TDL than by using human operator models.During previous research (10)(11)(12)(13)(14) , factors have been identified that influence pilot TDL for pilots flying an RNAV approach with a B747. These factors were identified based on flight simulator tests. In this paper it will be demonstrated that the same factors also influence pilot TDL when flying an approach with a Cessna Citation. This indicates that the set of factors that has been identified is a generally applicable set of factors, and not only valid for the B747. Additionally, it is investigated whether the same set of factors influences pilot TDL during flight simulator tests and during real flight. To this end, in this paper, both the results of a flight simulator experiment for a Cessna Citation and the results of real flight tests with a Cessna Citation aircraft are compared. It will be demonstrated that the same set of factors results from both experiments. Finally, the simulation tool that was developed for the B747 in order to analyse an approach with respect to the factors that were proven to influence pilot TDL is adjusted in order to include the Cessna Citation. It will be shown that the simulation tool also works and provides reliable results for the Cessna Citation.This paper is structured as follows. First, the basic principles of this research are introduced as well as the scope of the research. After that, the results of previous research (11)(12)(13) which focused on the B747 are briefly explained. Subsequently, the human in the loop experiments are presented, these experiments are conducted for the Cessna Citation aircraft both in a flight simulator and during real flight tests. To conclude, the simulation tool that is adjusted to include the Cessna Citation is explained, and its predictions are illustrated by a case study.