And you don't see yourself marked in those "sector radars", so if the line is as short as possible you might be 3 friendly in that plane (2 others + yourself).
Btw, I have also noticed that the horizontal divider between sectors in fact is located a bit south of where it is marked on the map, as far as for what sector the plane is considered to be in.
If you zoom in (RMB on the plus sign), and follow a friendly dot crossing the line, he needs to be a little way to the south of the line, before the sector "change" occur.
This can be useful information if you are sneaking a goon/buff along the border of a sector but are displayed to the enemy as being in another sector. As I said you can't see which sector you are being displayed in.
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Ltn. Snefens
RO,
Lentolaivue 34