My GM interprets this power as essentially a 15m blast. He says that is how it works because of the line "even then being within line of sight of the Navigator is dangerous." and that there is no facing in this game. The idea is that the Navigator's skull doesn't act as a barrier.
I would think it would make more sense if it was more like a flamer but, the rules mention nothing about what angle to use.
This became an issue because we were funneling some Orks up a ramp. The plan was for my character to use his flamer as they rounded a bend and then our Navigator to use his master level Lidless Stare them if they got too close. He was infront and to the side of me so, in theory none of use would get hit by my flamer or see his face.
Well I open up with the flamer and then he tries to use Lidless Stare. That is when the GM said that everyone around him, the whole party as well as the Orks, were hit due to his interpretation.
I am not sure what to quote to argue against this as it seems against the spirit of the power.