## 1 Introduction  
Several countries in South America and the Asia-Pacific region are frequently affected by natural disasters, such as earthquakes, tsunamis, landslides, and volcano eruptions. When these extreme events put urban areas at risk, a first response process is usually triggered by firefighting companies deployed in the affected area. In disaster relief efforts, typical participants include firemen, police officers, medical personnel and government agencies, and sometimes military units [1]. Every organization is in charge of specific activities that range from search and rescue to securing the affected area. In particular, firefighters and military units play a crucial role, since they are usually trained to address these challenges. Typically, electric energy is not available in the affected area, because the power distribution network is usually damaged or turned off for security reasons. Similarly, the infrastructure-based communication network is frequently damaged or collapsed; therefore the communication is mediated mainly by very high/ultra high frequency (VHF/UHF) radio systems [2]. In such a scenario, the most critical response activities should be performed during the first 72 h after the event (also known as the golden relief time), since after such a period the probability of rescuing people alive is very low [3,4]. These activities include search and rescue of victims, providing first aid to injured people, diagnosing the stability of physical infrastructure, establishing evacuation and re-entry routes, and securing the working area. These activities are interconnected and they are conducted by first responders belonging to several relief organizations. Coordination among these parties has a direct impact on the effectiveness of the initial response to a disaster. Typically, command posts deployed in the field try to coordinate the local activities, but they usually fail due to the unavailability of digital communication support and geo-referenced information that would allow them to know the status of the first response process [5,6]. Therefore, improvisation becomes the common denominator in those scenarios [7,8], which reduces the effectiveness of this process. Most research work done to address this coordination problem is focused on providing digital communication in the field in order to support interactions with first responders [5,9,10,11,12]. However, few studies have been done on increasing their positioning capability. Although most of the information used and updated as part of their activities is geo-referenced, only a portion of first responders deployed in the affected area have positioning capability. Considering the reality of many developing countries (e.g., all of Latin America), where the most important first response organization (_i.e._, the firefighters) is composed almost exclusively of volunteers, financed mainly by the community and typically with few resources to address these tasks, the proportion of people who could have positioning capability during a first response process is low. However, they usually have several outdated mobile computing devices given to them by the community, e.g., cellular phones and laptops, which opens up the possibility of increasing the positioning capability in this scenario. In order to help address this challenge, we propose a context-aware positioning model that takes advantage of computing devices with positioning capability (e.g., those embedding GPS), in order to provide positioning to those who are not able to do it by themselves. The proposed model enables devicesin outdoor scenarios to estimate their position based on information gathered from their direct context (_i.e._, their environment), regardless of their positioning capabilities. Devices using this model could estimate their position by sharing context and positioning information with their neighbors.