By nature, Cyber-physical systems are very often submitted to uncertainty events that can occur in their environment. This paper presents the first results of our work on how to deal with environment uncertainty in goal-based requirements engineering. This work is motivated by the fact that current goal-based approaches do not natively allow for unanticipated adaptations. To do so, we explore the introduction of RELAX concepts into SysMLKaos. RELAX is a Requirements Engineering language for Dynamically Adaptive Systems that include explicit constructs to handle the inherent uncertainty in these systems. On the other hand, SysMLKaos is a Goal Based Requirements Engineering approach that takes into account Non-Functional Requirements at the same level of abstraction as Functional Requirements and models the impact of Non-Functional Requirements on Functional Requirements. We use an extract of a Landing Gear System case study to illustrate the proposed approach.