The visibility-reducing effects of snow, fog, freezing rain, and other wintry weather phenomena at airports are well known and well documented. The same conditions can create problems when the precipitation comes into contact with aircraft.
The most critical problem with ice build-up on aircraft is that it changes its aerodynamics. This is why de-icing aircraft before takeoff is necessary during the winter in airports around the world to ensure the safety of passengers and crews. Every year, millions of litres of de/anti-icing fluids are used for this purpose. However, these fluids only provide protection for a limited period of time, known as “holdover time,” after which the aircraft will need to be re-treated.
Aircraft need to take off before the de-icing effect wears off to ensure the safety of passengers and crew, as well as to avoid delays. Therefore, it is crucial to optimize the timing of de/anti-icing activities, especially at busy airports.
Traditionally, flight crew personnel decide whether de-icing takes place by performing various assessments including visual inspection of the aircraft, evaluation of the prevailing weather conditions, and estimated departure time. SureWx™, a Canadian company with global operations, has established a more scientific approach by developing a system that determines the need for de/anti-icing and computes an optimized holdover time for the type of de/anti-icing fluid used in the prevailing weather conditions.
SureWx’s SureHOT+™ service is the world’s first and most advanced commercial de/anti-icing decision support tool. It uses various meteorological sensors, including Campbell Scientific’s PWS100 present weather sensor, to measure weather conditions at an airport at pre-determined intervals. The automated system uses the measurements to determine accurate holdover times for all de/anti-icing fluids on the market. The PWS100 uses a sophisticated laser-based technique, combined with temperature and relative humidity, to analyze the nature of precipitation and freezing fog. The type of precipitation is identified in detail, including mixtures, amount, and, critically, whether precipitation is freezing. PWS100 and sensor data are combined with information on the type of de/anti-icing fluid in use to calculate a holdover time. Campbell Scientific’s present weather sensors are designed to give accurate measurements in the harshest conditions and are, therefore, well adapted for this application.
Information on holdover times can be requested by flight crews at various stages during pre-flight activities and can be delivered electronically to the flight deck supporting more informed decision making. The results are more accurate de/anti-icing treatment times, reducing unnecessary and expensive delays.
An air carrier’s use of SureHOT+™ at airports where they operate also results in a significant reduction in the amount of fluid sprayed on aircraft—in particular, the quantities of thickened anti-icing glycol dispensed on aircraft. These fluids are designed to remain on treated aircraft surfaces until takeoff to prevent the accumulation of ice and other frozen contamination.
SureWx™ services are being used by air carriers around the world. SureHOT+™ delivers proven benefits that have resulted in advancing the operational, economic, and environmental aspects of aircraft operations in freezing weather, and Campbell Scientific is proud to be involved.