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pulsar, pulsar consulting

GNSS Failure Impact Simulation



  • Unix shell scripting
  • AWK Programming
  • Microsoft Foundation Classes C++ Human Machine Interface
  • SAAM Application


In the context of the future air traffic management where the only navigation control will be done through satellite system (GNSS only = Global Navigation Satellite System only), the strategic division of Eurocontrol, EATM, must make simulations of impact on the air traffic of GNSS failure combined with low visibility due to bad meteorological conditions (LVP). Thus, the name chosen for this project was “Simulation of GNSS failure impacts in LVP conditions in a GNSS only environment”.

The objective of the study was to evaluate the feasibility of the diversion of a large number of aircraft on alternate airports, in case of total GNSS environment and a complete failure of GNSS due to intentional interference when low visibility operations are in force.

The study identified the number of aircraft that could be impacted in two cases: already in flight and still on the ground. For the second category, the study assumed that the aircraft that have not already take off will stay on the ground. The study identified the total number of grounded aircraft and the growth factor versus time to be applied to this category of aircraft. This information was reported to evaluate the total impact of the disruption.

For the aircraft already in flight, the study ran the scenario to simulate the impacts of the failure. The first step of the study was to update the Eurocontrol SAAM tool in accordance to the necessary requirements to conduct the study. In particular, the SAAM tool allow the variation of the following parameters:

  • size of the area of GNSS outage according to the power of the interference source
  • size of the low visibility condition area and identification of the affected airports within this area
  • alternate destination range
  • landing capacity at affected airports.


Project Scope

The GNSS Failure Simulation project included:

  • the gathering of documentation from various sources
  • the meeting of aeronautical experts in order to see how the real world can be abstracted and modelled for the simulation
  • various preliminary data analysis (visual/statistical)
  • strong testings and visual verifications of the results
  • integration with external software such as eurocontrol's flight route processing and visualization modules.

The goal of this program is to provide statistical (application screenshot on the right, above) and visual data (graphic on the right, below) in order to support a study about the feasability and reliability of a GNSS-only navigation environment.

The blue triangles on this graphic represent flying planes. The vizualisations are real time animations. The red area represents the outage zone and the blue area the bad weather.



Business Flow

The program receives flight data and environment parameters as input and gives some statistics and visual simulations as output. The main process of this program is the splitting of the whole set of input flights into different categories representing the different situations in which the aircraft can be (e.g. an aircraft that flies below the MRVA level (Minimum Radar Vectoring Altitude) and that is inside the outage area when the failure occurs, an aircraft that have its route crossing the outage zone and cannot be diverted,...). On the business flow below, you can see an extract of the analysis document that describe this splitting. Following these situations, a flight can be considered as problematic or not, and the problematic flights can be counted and visualized as seen on the different pictures.


The diagram below allows to visualize the different steps of a flight route change. The green line stands for the original flight route that could not be used due to the outage. The blue line stands for the diversion attempt for the flight that needs a route change. The orange line represents the flight that should be diverted to an alternate destination airport.

This graphic shows another group of planes in a critical situation. The main part of these airplanes are long distance airplanes coming from or leaving a continent. Tese airplanes can nor be diverted to their original location, nor to their alternate airport, nor to any airport in the area. This number of flights will count for the final report in order to dertermine if a GNSS only environment is reliable or not.



This is another view of the situation. There are 2 distinct group of airplanes: the green ones and the red ones. The green airplanes are the airplanes that flew above the MRVA level at the time the outage occurs. Thus these airplanes are not concerned by the communication difficulties induced by a position under this level. On the counter part, the red ones are in a difficult situation. Indeed, they are not able to communicate anymore because they fly too low

To conclude, there is plenty of useful custom visualization that you can generate with this application. This allows users not only to perceive the actual situation but also to check the final numbers of the report with a concrete visual animated simulation.