The quality of signals of the Belgocontrol equipment can be influenced by physical obstacles, whether these are in the immediate vicinity of the antenna systems or not.
A physical object can influence electromagnetic radiation in several ways. On the one hand, it can absorb a part of the radiation, causing a shadow zone to be created behind the object in which the field strength of the signal is too weak.
On the other hand, the object can reflect a part of the radiation. This reflected signal can cause interference with the directly received signal, culminating in a signal quality loss and in erratic results.
Moreover, the object can give cause for diffraction of the electromagnetic radiation.
These disruptions can have serious implications for safety. A few examples :
- Reflections caused by ill-considered erection of buildings and other constructions can be the reason for an erroneous positioning of detected aircraft on the radar screen. Because of this, air traffic control can unknowingly decrease the normally required separation distance between two aircraft or between an aircraft and an object on the ground, with possibly dramatic consequences.
- If a construction is at the origin of a shadow zone for radar signals, aircraft in this zone will remain undetected and become an unknown factor for air traffic control.
- If the ILS (Instrument landing System) signal is disrupted by reflections on an object, there can be abrupt and sudden modifications in the approach profile, with possibly dramatic consequences for aircraft and passengers.
The signal of Belgocontrol equipment can be disrupted in such a way that the minimum signal requirements are no longer achieved. In that case, the equipment concerned needs to be degraded or even put out of service.
Moreover, Belgocontrol’s navigation, radar and communications systems can be disrupted by interferences from other transmitting equipment.
