Well put L337.
Everyone needs to remember that airborne weather radar normally looks 60 degrees left and right of the nose and in a very small vertical angle. The pilot can adjust the vertical to get a picture of what is above or below the aircraft but it takes time and skill to get a full picture of what is ahead which may be changing from second to second.
Of course as soon as a turn is required due to routing or the controller assigning a heading that picture is worthless and a new one must be aquired.
The "look out the window" argument is valid - but only when the aircraft is not in cloud or reduced visibility already!
Imagine being the controller on a sector from surface to FL155 where you could only see aircraft on the radar that were in bands of 3000ft and had to adjust the picture to see traffic higher up or lower down.
I would hope that pilots only turn without asking as a last resort to ensure the safety of the aircraft rather than simply turning to avoid a few bumps.
However, it happens and since both Pilots and controllers are required to have full knowledge of the weather affecting their operation, it seldom can be claimed to be unexpected that CB's are about.
Personally, I would say that the probability of having to make a turn without asking is higher in the area of communication transfer than elsewhere. The reason for this being not just that the pilot will have left the current frequency and not yet been able to check-in on the next but the situation often is that communication is transferred prior to the transfer of control point and even if the pilot asks the new controller, they often have to coordinate a change of track with the previous controller so the pilot (who has probably left it to the last minute) has no option but to turn.
I would be very surprised if controllers did not take that into account when weather avoidance could be required.
Originally Posted by Jagohu
And if we're talking about TCAS already - it'd be nice if pilots would start to notice that it's not a radar and shouldn't be used for self-separation.
I think what should be said is that TCAS should not be relied upon to determine the horizontal position of other aircraft relative to one's own.
TCAS is a very important self-separation tool but only in the vertical.
Regards,
DFC