  Rapid advancements in Artificial Intelligence have shifted the focus from
traditional human-directed robots to fully autonomous ones that do not require
explicit human control. These are commonly referred to as Human-on-the-Loop
(HotL) systems. Transparency of HotL systems necessitates clear explanations of
autonomous behavior so that humans are aware of what is happening in the
environment and can understand why robots behave in a certain way. However, in
complex multi-robot environments, especially those in which the robots are
autonomous, mobile, and require intermittent interventions, humans may struggle
to maintain situational awareness. Presenting humans with rich explanations of
autonomous behavior tends to overload them with too much information and
negatively affect their understanding of the situation. Therefore, explaining
the autonomous behavior or autonomy of multiple robots creates a design tension
that demands careful investigation. This paper examines the User Interface (UI)
design trade-offs associated with providing timely and detailed explanations of
autonomous behavior for swarms of small Unmanned Aerial Systems (sUAS) or
drones. We analyze the impact of UI design choices on human awareness of the
situation. We conducted multiple user studies with both inexperienced and
expert sUAS operators to present our design solution and provide initial
guidelines for designing the HotL multi-sUAS interface.
