Most re-entry vehicles utilize a Descent and Landing System (DLS) for a safe descent through the lowest part of the atmosphere. It usually requires deployment in a certain suitable range of flight conditions, which has to be estimated by limited means of navigation. This paper presents a comparison of currently used trigger methods and triggering algorithms which are based on correlation between in-flight measurements and the DLS triggering conditions, where the correlations have been extracted by multiple Monte Carlo campaigns. This approach gives a significant improvement of triggering accuracy over direct measurements for a ballistic re-entry. Also a lateral g-load safety trigger is developed to prevent the angle of attack oscillation escalation. Furthermore a sensor sensitivity analysis is performed for a lifting entry trajectory in order to support an upcoming ESA re-entry mission. The velocity drift appears to be the dominant dispersion by a factor ten for Mach estimation. Finally a case study has been performed to investigate the possibility to reduce the footprint by a dynamic parachute opening window. This could be effective for Mars reentry using a parachute able to deploy beyond Mach 2.5, which would reduce the footprint by up to several tens of kilometers. Nomenclature