Each activity or work performed by a worker will always contain a workload. Such workloads include both physical and mental workloads arising from the work environment. Different work time conditions are also deemed to affect the mental condition of a pilot. The aim of this study is to measuring the value of pilot mental workload in terms of difference pilot age to operate the aircraft based on the difference in phases of time. Subjective Workload Assessment Technique (SWAT) method is used to measure mental workload value, this method consists of three dimensions with their levels, there are: time, mental effort, and psychological stress load. The results of this study indicate that the conditions with the highest mental workload for the group one consisting of 26 pilot respondents (aged <30 years) were at the time flights were made in the morning (06:00 to 11:59 am), during weekends, and during peak seasons. While the results for group two (pilot age ≥51 years), indicating that the conditions with the highest mental workload were at the time flights were made in the early morning (00:00 to 05:59 am), during weekends, and during peak seasons. This study also showed that the time dimension factor (T) significantly affects the mental workload of pilots, indicating that they put more emphasis on this factor when they are considering workloads.