## 5 Conclusions  
The research was focused on answering the question of whether it is appropriate to use the photo-optical method to measure selected data on the movement of the M-282 parachute. The performed parachute jumps confirmed that the photo-optical measurement method is a suitable method for measuring the vertical speed of the M-282 parachute with the potential for further work to verify the methodology for general use, other types of parachutes, and digital cameras for motion detection. The photo-optical method (in a modified form) is also suitable for to analyze the trajectory of a parachutist's movement in the context of a parachutist accident investigation [29]. A major benefit of the photo-optical method application is that measurements can be taken without installing measuring devices on the flying object. An important advantage for practical utilization is that, within the resources presented above, methods for the measurement of a parachute's vertical speed were processed and developed. These methods can be applied for verification of the parachute capacity before its integration in flight operations. The comparison of results indicates that the process of identifying the vertical speed of the parachute using the photo-optical method was correct. Our developed and verified measurement procedures of the photo-optical method, technological conditions for the measurement of the parachute vertical speed, analysis of influencing factors, and quantification of these factors' influence on the measured results complete the normative documentation for personnel parachute technical testing [10; 11; 14]. The authors also recommend this method to other researchers, athletes, or sports coaches. The novelty of our work lies in the application of the photo-optical method for the purpose of measuring the vertical speed of a parachute. In general, this method is applicable to any flying object and also to horizontal speed or total speed. Based on the research results, the photo-optical measurement method can be validated in the future for other types of digital sensors (cameras) to detect the movement of a parachute or to investigate the influence of other devices affecting the results of vertical speed measurements. Conceptualization, [PERSON] ([PERSON]) and R.R. ; methodology, [PERSON] ([PERSON]); validation, [PERSON] ([PERSON]); formal analysis, [PERSON] ([PERSON]), R.R. and P.K. ([PERSON]); investigation (jumps), [PERSON] ([PERSON]); resources, [PERSON] ([PERSON]); data curation, [PERSON] ([PERSON]); writing--original draft preparation, [PERSON] ([PERSON]), R.R. and M.K.J. ; writing--review and editing, [PERSON] ([PERSON]), R.R., M.A., J.S. and M.D. ; visualization, [PERSON] ([PERSON]), M.K.J. ; project administration, [PERSON] ([PERSON]); funding acquisition, [PERSON] ([PERSON]). All authors have read and agreed to the published version of the manuscript. This research was funded by an internal grant of the Slovak Aeronautical Institute (SAI) and Ministry of Defense of the Slovak Republic. This article was supported by the Slovak Research and Development Agency under contract No. APVV-17-0167--\"Application of the Self-regulatory methods for the Preparation of Flight Crew\". **Institutional Review Board Statement:** Not applicable. **Informed Consent Statement:** Not applicable. **Data Availability Statement:** The data presented in this study are available on request from the corresponding author. Data were obtained from the Slovak Aeronautical Institute Kosice [third party] and are available from the corresponding author with the permission of a third party ([PERSON] Directive for parachute and paratrooper equipment testing. SAI Kosice, 2019). **Conflicts of Interest:** The authors declare no conflict of interest. Appendix A Analysis of Influencing Parameters and Quantification of Their Influence on the Uncertainty of Measurement Results  
The uncertainty of the measurement results of the vertical parachute speed using the photo-optical method was performed in compliance with the TPM 0051-93 [29] regulation.