Airport capacity reduces due to low visibility, resulting in delays, diversions and cancellations leading to increased workload and additional operational costs/expenses. Based on the forecast of low visibility conditions, flow restrictions are enforced to reduce this operational impact. This is acceptable as long as the forecasts are accurate and reliable, that is, the forecast equals correctly predicted the observed conditions (Hits). Visibility conditions worse than forecasted (Misses) or better than forecasted (False Alarms), increase the operational costs unnecessarily and such erroneous forecasts should therefore be limited as much as possible.
An analysis has been made on the occurrence of low visibility and ceiling. It showed the very low occurrence of conditions with Low Visibility Procedures (LVP-phases A, B, C and D occur in total less than 5% of the ATM operational time per year).
Several improvements to the forecasts have been proposed, developed en verified. The new TAFG and SKV show a significant improvement in accuracy and reliability.
R ten Hove (ed), JB Wijngaard (ed). Improved Low visibility and Ceiling Forecasts at Schiphol Airport
KDC/2008/0089 - KNMI publication 222, 0--2008, pp0