  [Context & motivation] Driven by the need for faster time-to-market and
reduced development lead-time, large-scale systems engineering companies are
adopting agile methods in their organizations. This agile transformation is
challenging and it is common that adoption starts bottom-up with agile software
teams within the context of traditional company structures.
  [Question/Problem] This creates the challenge of agile teams working within a
document-centric and plan-driven (or waterfall) environment. While it may be
desirable to take the best of both worlds, it is not clear how that can be
achieved especially with respect to managing requirements in large-scale
systems.
  [Principal ideas/Results] This paper presents an exploratory case study at an
automotive company, focusing on two departments of a large-scale systems
company that is in the process of company-wide agile adoption.
  [Contribution] We present challenges related to requirements engineering that
agile teams face while working within a larger plan-driven context and propose
potential strategies to mitigate the challenges. Challenges relate to, e.g.,
development teams not being aware of the high-level requirement and dealing
with flexibility of writing user stories. We found that strategies for
overcoming most of these challenges are still lacking and thus call for more
research.
