If it is legal for the navy ships to sail in the VTS without transmitting AIS signal, then they must first inform the VTS, and the VTS must manually plot them on the RADAR? Normal procedures when arriving a VTS is that the vessel report their arrival and the VTS find the vessel on his screens, and collect the information from the vessel.
The VTS must in the time before the accident have a fast moving target on the radar that are not identified, I assume that they do plot the vessel in the area of the VTS on the radar. However, it can look like, at least this time they was depending only on AIS, and ECDIS.
It also strikes me, that with so many people on the bridge of HI that nobody heard that Sola TS was leaving Sture.
Strange is it also that at the hand over OOW only 5 minutes before the collision, must have plotted his position, and seen that nothing was in front of him on the chart or radar at present course. If it appears a few minutes later, it must be a moving object
HI had the AIS receiver (but not transmitter) on so they could see other ships name etc., what we do not know is the status on the AIS on Sola TS, was it “alongside”, or “underway”. On the other hand, did HI use the ECDIS so they could also see where they and other ships were positioned relative to land, or was they plotting on paper chart?