Low ceilings and reduced surface visibilities yield critical impacts across the spectrum of aviation activities. For the general aviation pilot, limited ceiling and/or visibility (C&V) present a significant safety hazard – one that must be carefully considered in making pre–flight go/no–go decisions, route plans, and in–flight IFR avoidance and escape decisions. For commercial aviation, advanced aircraft equipment and pilot experience enable safe operations in low C&V conditions, but traffic flow capacity at impacted terminals drops markedly. This reduction in capacity is a major cause of flight delays and cancellations, and can propagate 'upstream' from impacted terminals to feeder terminals where no C&V problem exists.

RAL's work toward C&V nowcasting and forecasting addresses both the safety and terminal capacity impacts outlined above.