It is a pity that [Steve]'s concerns about the potentially dangerous use of a grease pencil mark on a window to assess collision risk has been so lightly dismissed, particularly by misd-agin, who confidently states
When you use this technique you'll know, while sitting in the Captain's seat, where your wingtip will be.
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Sorry, but you simply can't KNOW that.
Steve's point was that the alignment gives a slant sight down to a point on the ground, so any object above said slant line, whether closer to you or not, will appear to be safe using this flawed technique.
misd-agin then goes on to misinterpret Steve's argument as suggesting it is safe to pass a wingtip over an object, which he patently was NOT suggesting.
This technique is flawed in many ways, and thankfully the original contributor has either removed his suggestion, or it has been done for him. Any error of just 1 cm in eye position, being 30cm or so from the window, will be magnified around 100 times at wingtip distance, giving a potential error in the order of metres. Sadly that was all it took in this unfortunate circumstance.
Anyway, for this method of sighting to work effectively, it pre-supposes the use of a head-clamp when seated, and that all obstructions (including aircraft tails and wings) conveniently be built vertically, with no overhangs. Sadly, in the real word, they are not, as in the design of the Comair's tail!
So to clarify, after placing our cone on the ramp, as we run back up to the flightdeck - no small journey on an A380 - how can we be certain that nobody has moved our cone? Then we must run back down to remove the cone after making our mark. Are you guys serious? Frankly, I have better ways to use my time on arrival at the aircraft.
Then there is the issue that we generally fly different aircraft each day, and we all sit slightly differently, so nobody else's grease pencil mark is any use to the next pilot. So this time-consuming process must be repeated each new duty, with removal of the grease mark each time too, and all in pursuit of a dangerously flawed technique.
I don't think so.