Pilots who want to land at Sabiha Gökçen Airport in Istanbul have been encountering mysterious signals for the last few days. Despite the researches carried out in the air, land and sea, the source of strange signals has not yet been identified. Experts thought that a ship or drone signal could lead to these alarms and informed the coastal safety and other teams. However, there was no trace in the calls. Sabiha Gökçen Airport evaluating the signals that cannot be identified on the retired captain Pilot Engin Aksüt stated that this cannot be a drone attack and said, “In order for the TCAS system to operate, the other aircraft should have a system that we call Transponder. Therefore, the cause of the traffic warning of the aircraft cannot be the drone. Because there is no transponder on the drones ”.
Is the reason low flights?
According to Aksüt, the reason for these signals may be a helicopter or airplane that is parallel to the beach. Aksüt said that the aircraft that approached the traffic warning on the sea.At the time of reporting the events, a research can be conducted in the Flight Radar 24 system and the position of small aircraft or helicopters in those vicinity can be determined. These traffic warning incidents in Sabiha Gökçen may also be caused by a signal turmoil in the ship tracking system of the ships in this approaching line or anchored in this approach line. ”
Does it cause danger?
Evaluating whether the signals would threaten the flight safety, Aksüt gave the following information: “If an airplane in an approach with such a signal view is low on 1000 fit (333 meters) and this signal requires an escape maneuver, the aircraft will probably make this maneuver as a climb. It can create a Domino effect in the airspace, and there may be a weak risk of maneuvers. When TCAS gives a traffic warning, the pilots look at that direction and try to find the aircraft they get warned, but do not make any escape maneuver. However, if they receive the avoidance warrant TCAS and if there is a low opinion, they have to apply the maneuver command they receive without question. This will also affect other aircraft in the surrounding area. “
There may be signal tests
An aircraft technician we talked about on the subject, the exposed signal tests may be the cause of mysterious traffic, he said. Aircraft Maintenance Technician, who says that there are aircraft maintenance hangars at Sabiha Gökçen Airport, “From time to time in these hangars, the TCAS system of the aircraft is tested. While making this test, the ghost TCAS information is entered into the test device and the position of another aircraft in the desired height and location is simulated and the TCAS system of the aircraft in the maintenance is tested and calibrated. ”

How should tests be performed?
The technician gave the following information: “Normally, such a test should be performed in the hangar in order not to send TCAS signal to other aircraft. If such a test was made exposed and the device remained open in test mode for a long time, there is a possibility that aircraft approaching Sabiha is likely to buy traffic warnings. In order to find out how valid this possibility is, it can be learned whether such a test is planned when TCAS tests from the Hangar Avionic workshops at Sabiha Gökçen Airport are examined. ”
While the work of pilots and tower officials related to the signals on Sabiha Gökçen Airport is continuing, the reason for this unknown traffic in Istanbul skies has not yet been found.