What do SLD limits indicate?

• A. Continued flight in SLD conditions is prohibited and such conditions can be detected by accretion on side windows
• B. SLD conditions allow limited operations with flight crew caution
• C. SLD refers to surface-level daylight conditions with no impact on flight
• D. SLD conditions only affect autopilot performance

Answer: (A)

SLD stands for Supercooled Large Droplets icing. In these conditions, large droplets freeze on contact with surfaces, causing rapid and often uneven ice buildup that standard anti-ice systems may not manage. This creates big hazards: loss of visibility, changed aerodynamics, and potential control issues. Because of that risk, the limits state that continued flight in SLD conditions is prohibited, and a practical sign that you’re in SLD icing is ice accretion on the side windows. So the best interpretation is that you must not continue flying in these conditions, and the presence of side-window icing is an indicator that SLD icing is affecting the aircraft. It isn’t about daylight, and it isn’t only about autopilot or a minor surface condition—it's an icing hazard that requires stopping the flight.