There have been other claims that because a radar transponder
on the St Phelim failed, the HMS Penelope on an exercise mistook the aircraft for a target drone.
It interacts with an aircraft's radar transponder
to determine the plane's identity, altitude and position.
However, there has been no attempt to enhance the adhesive bond between radar transponder
Investigators suspect the aircraft's radar transponder
was turned off at about that time.
According to the company, SSR is used to send a message to an aircraft equipped with a radar transponder
and collect information that allows air traffic controllers to identify, track and measure the location of that particular airplane.
In addition to replacing the antenna, Northrop Grumman will modify the B-2 defensive management system and the radar transponder
to support the change in operating frequency.
Military and large commercial aircraft are the easy part of the problem, because they generally fly by instrument flight rules, which require them to be in constant contact with an air traffic controller (ATC) and have an actively operating radar transponder
. In the US, however, ATC contact is only required in heavily traveled areas.
It appears that the Russian aircraft's radar transponder
signals were not received by the air traffic control nor by the collision warning system of the Finnair aircraft and as a result, the Finnair pilot was warned only five seconds before the two aircraft flew past each other.