## 1 Introduction  
The presence of water, ice, or snow [1] on runways has led to numerous aircraft accidents [2]. Runway excursion is a major risk in the aviation industry [3; 4; 5], especially when aircraft must use icy runways, such as in Canada [6; 7]. For example, on 8 February 2019, a thin layer of ice covering the runway at Bagotville airport (Saguenza, QC, Canada) led to an aircraft leaving the runway after landing [8]; fortunately, there were no injuries. Such accidents often result in significant property damage [9], and the frequency of incidents during winters negatively impacts airport operations at higher latitudes [10]. To ensure safe aircraft take-off and landing, airports remove winter contaminants (e.g., snow and ice) using mechanical tools and/or prevent their accumulation. Standard runway maintenance operations in regions subject to freezing, e.g., Canada and the northern United States, involve applying thousands of tons [11] of de-icing products in liquid (aqueous solutions) or solid form. Despite the importance of winter conditions on airport operations and budgets, little effort has been made toward evaluating de-icing and anti-icing product performance or determining the optimal amounts of product to be applied to runways [12; 13; 14]. Product suppliers typically suggest application rates [15; 16; 17] and the duration of product effectiveness on the basis of their own experience and knowledge. Snow accumulated on runways is removed using mechanical tools [18]. For ice, chemicals known as runway de-icing products (RDPs) are first applied to facilitate melting before its removal by mechanical means. Moreover, maintenance crews may initially spread RDPs to prevent ice from forming on the runway [19]. Three standardized tests are conducted jointly to determine RDP performance: ice melting [20], ice penetration [21], and ice undercutting [22]. Here, we focus on ice melting, which is the main property that interests maintenance managers when they assess the utility of an RDP. Ice melting occurs when energy is added to the ice, causing it to melt. This added energy may be heat, a chemical, or another substance. The ice melting test estimates the amount of ice mass that an RDP will melt per minute, as described with the AS6170 test method standard [20] which was developed by an SAE G12 working group. However, the main shortcoming of this test is the absence of a failure value or minimum value, which leaves the results open to too wide of an interpretation. Determining the term \"performance\" is essential to understanding what is expected of the RDP. Performance can be expressed in terms of melting rate but also in terms of the product's endurance, how long it reacts. As this notion is not addressed in the standard, it is difficult to estimate what performance is expected during the test. Ice melting is also influenced by various parameters inherent to airports: solar radiation, convective effect of wind, temperature variations, mixed icing conditions (snow, rain, ice, etc. ), passing vehicles, and the presence of contaminants (aircraft fluid or fuel). Unfortunately, these parameters are not included in the test. So, ice melting is a comparative test, under controlled conditions, but needs further investigation. The output is a 3D measurement (mass or volume per minute) representing the speed at which a given product melts ice [12]. Much research has been conducted on liquid de-icers [23; 24] but less on solids because of factors such as granulometry. Studies on solid RDPs often focus on NaCl and MgCl\({}_{2}\)[25; 26; 27]. Procedures for testing the melting capacity of ice rely on tools such as isothermal bottles [28] and ice cubes [29]; however, these methods require manipulation during testing, which increases the potential for error. Here, we apply two methods to characterize ice melting through RDP use. The first, thermography, is commonly used in winter operations to measure the surface temperature of pavement (e.g., roads and airports) [30].