Aircraft De-icing

posted on 2nd October 2019
Aircraft De-icing

Canada’s Toronto Pearson International Airport – Canada’s largest airport in terms of total passenger traffic and North America’s second-largest in terms of international traffic – is one gateway that has gone down the road of centralised aircraft de-icing, and seems to have reaped the benefits.

For such a big and busy gateway it is vital that its operator, the Greater Toronto Airports Authority (GTAA), ensures that flights through the gateway are kept moving no matter how bad the weather becomes – and Canada’s winter, even in the far south-east of the country, can be hard.

The de-icing season in Toronto typically begins in October and finishes in either April or early May. The number of aircraft that require treatment is highly dependent on the weather, of course, but de-icing season aircraft spray totals have ranged from approximately 13,000 to over 19,000 during the 2018/19 winter.

The current five-year average for is 15,500 per season. The record highest daily number of aircraft sprayed is 510.

At Toronto Pearson, all de-icing is undertaken at the gateway’s Centralized Deicing Facility (CDF), which – the GTAA says – is “the largest and most technologically advanced of its kind in the world”.

The CDF occupies approximately 65 acres of land. It incorporates underground collection systems and is specifically surfaced to reduce the environmental impact of the chemicals used in the de-icing process (primarily the glycol-based chemicals).

The CDF is an ‘engines-on’ facility consisting of six pads which are each sub-divided into a de-icing area and a staging area. Each pad can accommodate two widebody planes (for a total of 12) or four narrowbody aircraft (for a total of 24 airplanes), with a simultaneous de-icing capability of six widebody or 12 narrowbody aircraft.

According to Ken Eastman, director of deicing operations at the GTAA, having the CDF offers a whole range of benefits. “Eliminating aircraft de-icing from the terminal buildings allows Toronto Pearson to optimise our gating ability, mitigate our environmental impact and maximise resources at the CDF.”

Moreover: “Having a CDF gives our airline partners the ability to have consistent access to the terminal and lets us optimise the gates and stands to maintain our airside flow.”

And as regards the environmental benefits: “The CDF was designed to capture and collect all of the fluids within our 65-acre footprint,” Eastman confirms. “The entire site is lined with a geothermal membrane to ensure glycol won’t penetrate soils below the CDF surfaces.

“The CDF pads are graded on a slight slope from north to south and spent fluids are collected in catch basins that flow into larger diversion vaults. Fluids are tested in the diversion vaults and then directed to the appropriate collection tanks based on the glycol concentration of the fluids. High-concentration spent fluid is then processed at the on-site glycol processing facility, where the fluid is recycled to 50% concentrated glycol and used in other after-market products.”

Since the winter of 2015/16, de-icing services at Toronto Pearson have been provided solely by the GTAA. The current team consists of approximately 190 staff and they operate up to 46 de-icing units (the unit is equipped with one-man operated Vestergaard Elephant Beta de-icing units).

The team consists of de-icing specialists, equipment mechanics, operational management staff and de-icing movement co-ordinators, who communicate with the de-icing vehicles and aircraft for smooth flow through the CDF while making use of automated guidance technologies.

The CDF at Toronto Pearson is a 24/7 operation that communicates with pilots, equipment operators and air traffic controllers to service aircraft as quickly and safely as possible.

That efficiency is such that the average time taken to de-ice/anti-ice an aircraft is less than five minutes, with a total throughput time of less than 14 minutes. These times are inclusive of all the environmental conditions that have to be combated – frost, light snow, moderate snow, heavy snow and ice.

The GTAA Deicing Operations Program is audited and monitored by national policy-maker Transport Canada, as well as the airline stakeholders that utilise the CDF.

Word of the effectiveness of the CDF has spread far and wide. “We have frequent requests from airport operators/airline operators and government regulators to understand the procedures, practices and technology being utilised at the Toronto Pearson CDF,” says Eastman.

“Our CDF is recognised as an industry leader in how we approach aircraft de-icing. We are continuously working with airport operators, airline operators and industry experts to ensure that industry best practices are shared.”

Nevertheless, the GTAA says that it continues to investigate areas of potentially yet more operational improvement and efficiencies for the CDF. In recent years, the airport has expanded its infrastructure, changed its operating methodology, and increased its equipment resources to optimise operational capacity.

In 2018, it took delivery of two new glycol recovery units; one is capable of runway rubber removal as well. In 2019, it received its sixth under-wing de-icing unit.  The GTAA is also currently expanding Pearson’s underground storage capacity with the construction of an additional 5 million-litre tank.

Denver International Airport (DIA)

Far to the west of Toronto, the US state of Colorado’s biggest city, Denver, is home to Denver International Airport (DIA). The ‘Mile High City’ is a jumping-off point for many of the skiers making their way to nearby ski resorts in the Rocky Mountains, all of which gives some clue to the fact that – as at Toronto – snow and ice are not unknown phenomena in Denver and at DIA.

In fact, during the most recent winter season a total of 17,000 aircraft were de-iced at the airport. The de-icing season at DIA extends from 15 September to about 15 May, and – confirms Bruce Goetz, director of airside operations at the gateway – “Generally there are more de-icing events than snow events.”

Unlike at Toronto, the commercial carriers flying through DIA are responsible for the de-icing of their own aircraft. However, like the Canadian gateway, it too offers a number of off-gate facilities at which the de-icing process is undertaken. DIA has six de-icing pads for commercial carriers and two for cargo carriers, with a total of 33 spots between the six pads. De-icing at aircraft gates is limited to a procedure involving no more than 25 gallons of fluid, which is used to clear the windows of the aircraft so that they can safely taxi to the pads.

The commercial carriers use four de-icing service providers – Swissport, IDS, Aeromag (for United) and Southwest – and it takes approximately 29 minutes for a narrowbody aircraft and approximately 31 minutes for a widebody to be fully de-iced. Each airline has their own de-icing procedure, varying by aircraft type and provider, Goetz informs.

The airport authority is generally just an observer vis-a-vis the actual de-icing process, he continues. “The airlines are responsible for de-icing their aircraft, and each have different procedures on how they want their aircraft de-iced. Additionally, their internal companies undertake safety reviews and analysis that drives both safety and efficiency.”

However, airport team members attend weekly meetings with the airlines and the de-icers to discuss a wide range of topics, including safety, efficiency and fluid status.

The airport owns the infrastructure for the de-icing distribution system to several of the pads. DIA is able to collect about 75% of the sprayed fluid – one of the highest capture rates in the world. The operator contracts with Inland Technologies to manage the distribution system, which also mixes the de-icing fluid. Inland re-distils the collected fluid to approximately 99% purity. It is then sold for other industrial uses.

Regarding efficiency, Goetz points out that the operator has purchased the Aerobahn Deice Queue product. This system gives the airlines a recommended off-block time to push off the gate and flow directly to the de-ice pads. This minimises the amount of time the aircraft are running engines and waiting in line to be de-iced.

All of the de-ice pads are for common use, so DIA handles their allocation. The airport authority undertakes a thorough analysis of the schedule, and works with the airlines to distribute the pads equitably, Goetz says.

Collaborative efficiency

As in North America, so in Europe different airports choose different aircraft de-icing methodologies. Munich Airport, which handled some 46.3 million passengers last year as well as not far short of 380,000 tonnes of air freight and mail, operates a number of remote de-icing areas.

Bavaria’s busiest gateway is no stranger to snow and ice, but there is no time for cancellations and little sympathy for delays due to harsh weather conditions. “In an average winter, we usually de-ice about 9,000 aircraft (looking back over the last five years),” says Alexander Hoffmann, vice president airport operations at the airport’s operator, Flughafen München.

There can be up to 15,000 de-icing events in any given winter, depending on that year’s weather conditions. At Munich, the winter season officially begins on 1 October and ends the following year on 30 April, but it can be shorter or longer depending on weather conditions.

Most of the airport’s de-icing is carried out from November through to March, with the busiest month last season being January, which saw a total of 5,098 de-icing treatments.

There is only one aircraft de-icing service provider at the gateway. EFM (owned by Lufthansa and Munich Airport) is a specialist for both aircraft de-icing and pushback service. The company uses Vestergaard Elephant Beta vehicles for de-icing (in single-man operations). How long each de-icing takes is dependent upon the size of the aircraft, the amount of frozen contamination and the current weather, and can thus vary between seven and 30 minutes, says Hoffmann.

Munich has 12 remote de-icing areas at its four runway heads. Approximately 99% of aircraft de-icing events are undertaken at these four areas.

Flughafen München introduced the remote area de-icing concept at the opening of the airport in 1992 with two main goals in mind, says Hoffmann. The first objective was to install centralised (remote) de-icing areas at the four runway heads in order to collect the de-icing fluid and recycle it for further use.

The second goal was to keep the time buffer between aircraft de-icing and take-off to an absolute minimum. “In this context, special de-icing procedures as well as special communication procedures were established in order to ensure permanent data exchange between ATC [air traffic control], EFM and aircraft operator for efficient de-icing stand allocation,” Hoffmann recalls. “And concerning the safety aspect, special monitoring and control procedures exist for after-de-icing checks of each aircraft.”

In an ongoing effort to maximise the efficiency of the de-icing system, “Our provider EFM is constantly working on process improvements,” he says. “In addition, we will start planning activities to enlarge our existing aircraft de-icing infrastructure at Munich Airport within the next [few] years.

“The efficiency of the aircraft de-icing process heavily depends on the existing airport A-CDM (airport collaborative decision-making) process, which works with dedicated aircraft de-icing parameters and thus continuously delivers data and information regarding aircraft de-icing status to ATC, EFM, Flughafen München and aircraft operators,” Hofmann concludes.