On a sunny November afternoon, crews from Integrated Deicing Services watched as a Boeing C-17 Globemaster III parked on the Sierra deicing pad at Pittsburgh International Airport.
Once the jet came to a full stop, two deicing trucks pulled up on each side of the aircraft and began their delicate maneuvers around the gigantic transport plane, including the forward fuselage, wings and tail.
IDS performs all deicing operations for the 911th Airlift Wing, the Air Force Reserve station at PIT that operates seven C-17s. Each year, IDS operators drill before winter, allowing deicers to become accustomed to working around the 141-ton aircraft.
Winter operations can be volatile, said Master Sgt. James Williams, an aircraft maintenance supervisor with the 911th.
“If any snow or ice freezes on the aircraft, it all must be removed before takeoff,” Williams said. “Without deicing, we could be looking at putting the aircraft in a hangar or shutting down flight operations.”
Similarly, the 171st Air Refueling Wing of the Pennsylvania Air National Guard, also based at PIT, trains its crews each year before the winter season to prepare its airmen for deicing operations.
The 171st flies the Boeing KC-135 Stratotanker, the primary tanker for the Air Force. The mission of the KC-135 is conducting aerial refueling of aircraft, including fighters, bombers and cargo transports.
All deicing for the 171st is performed by the base’s Maintenance Squadron.
Maj. Alex Steel, commander of the 171st Air Refueling Wing Aircraft Maintenance Squadron, said that preparations for the winter season begin during the summer and fall.
“Equipment and vehicles are inspected, deicing fluid samples are tested for quality and personnel receive refresher training on deicing operations and ramp procedures,” he said. “Our deicing procedures contain multiple stages and steps depending on the weather conditions.”
Methodical and safe
Military aircraft follow the same standards for deicing as commercial aviation .
The process beings by removing as much snow from the aircraft as possible. Special rakes and air blowers mounted to trucks are used to clear surfaces of the airplane—both are useful if the accumulated snowfall is light.
In the case of a wet or heavy snowfall, Air Traffic Control will direct the aircraft to one of PIT’s three deicing pads: Charlie, Sierra or fixed-base operator Atlantic Aviation. Charlie can work on as many as five aircraft at once; Sierra can hold up to six.
The deicers then run a truck-mounted boom over the aircraft and apply a heated mixture of propylene glycol and water to remove remaining snow and ice. An operator inside a cab controls a nozzle to spray the deicing fluid.
If necessary, sprayers will also apply an anti-icing fluid that prevents the buildup of snow and ice. Crews take into account temperature, type of precipitation, wind speed and rate of accumulation to determine how long it will take for snow and ice to build up again.
It typically takes about 12 minutes to deice a plane, although a variety of factors can affect that turnaround time, including weather and aircraft size .
Leftover deicing fluid that collects on the pad must be recovered and recycled. Special trucks called Glycol Recovery Vehicles are used to collect excess glycol off the pavement. In addition, every deicing pad at PIT is surrounded by trench drains that capture fluid and precipitation, which runs down and into above-ground collection tanks that are routinely monitored.
Excess glycol is stored in these tanks until it is collected and transported away by a waste recovery agency to be recycled. PIT was one of the first major airports in the U.S. to begin managing and collecting deice fluid.