# Decentralized Documentation of Maritime Traffic Incidents to Support Conflict Resolution
## 1 Introduction  
In the 1960s, the first regulations to make flight data recorders (black boxes) mandatory were adopted in several countries. Back then, primitive analog systems had been used to record primary flight data such as altitude, airspeed, heading, and acceleration [1]. Several decades later, more convenient digital flight data recorders are used that can precisely record over 100 variables simultaneously [2]. Compared to the aviation industry, continuous recording of data for marine casualty investigations was introduced several years later, in 1997, by IMO Resolution A.861(20), which was also included in the International Convention for the Safety of Life at Sea (SOLAS). According to SOLAS chapter V [3], passenger ships and ships of 3000 gross tornages and upwards, which are constructed after a specific date, shall be fitted with a voyage data recorder (VDR) to assist in casualty investigations. Since then, VDRs have been used to analyze shipping accidents in official investigations; for example, in the investigation of the grounding and partial sinking of the Costa Concordia in 2012 [4]. However, VDRs are tightly secured devices, and their disassembly, and especially data extraction and analysis can be a complex and time-consuming manual process [4]. Also, according to the IMO casualty investigation code, investigations are regulated by the national authorities, which often only initiate official investigations for serious accidents that lead to the total loss of a vessel, loss of human lives, or significant environmental pollution (e.g., as regulated in the Maritime Safety Investigation Act of Germany or theMerchant Shipping (Accident Reporting and Investigation) Regulations of the UK). This leads to several problems in investigating less severe accidents or critical traffic situations, especially from the perspective of data acquisition. Data from the vessel's sensor systems or surveillance data is one of the essential puzzle pieces for tracing the chain of events that lead to such a situation. As today's vessels often have sizes of 300 m in length or larger, even smaller accidents can lead to major financial losses for the involved participants in an accident. Additionally, law enforcement can become a problem as ships often sail under the flag of micro-states, and international enforcement of the law is extremely costly. In the best case, data acquisition must happen immediately after an incident. Still, in busy port areas, damages to port infrastructure, e.g., quay walls, may not always be recognized directly after the incident, and it may not be clear how the damage occurred. In these cases, there often exists multiple data sources that could contain data that is related to such an event. Nevertheless, if no official authority is coordinating the process of data acquisition and analysis, trust issues may arise between the involved parties regarding the authenticity of the data. From this, it can be seen that there is a need to collect data in potentially critical maritime traffic situations that may lead to accidents while maintaining trust between all different involved parties in the case that the recorded data may be used in a later analysis of such a situation. Apart from that, the provision of a guarantee between the traffic participants that the data has been recorded at the point of the event, and was not modified, is also important to maintain trust. Therefore, in this paper, we propose a new method for recording vessel traffic data from multiple parties, with the intention of using this data in an incident investigation while guaranteeing non-repudiation of the recordings. In Section 2, we initially provide relevant background information on current standards for Maritime Accident Investigations, Data Protection, and existing procedures for the secure storage of distributed data. On this basis, we subsequently derive requirements for a system for the documentation of critical traffic situations. Section 3 takes a closer look at the related work.