I may of found my problem thinking in why I can't see that the beam I witnessed could have been a contrail shadow. I imagined the light from the sun as coming from the small sphere of the sun that I see. I can see by your drawing I am seeing it wrong. Okay I am getting closer to understanding, gotta go and do stuff so I will use this new understanding now. I have to go draw some pictures of my own. I may be back.
Have you seen this thread? It covers some "weird" contrail shadow effects. (It also shows a not atypical attitude of a chemtrail believer who has run up against some science, but that's by the by!)
Yes, I see the point of that diagram nowRight, but I was referring to this diagram.
It's tempting to imagine the sun as being much closer, even below the clouds, and for all the rays to come from the sun. Notice I drew in several parallel rays. The point being that even when the sun looks like it's illuminating clouds from below, then if you can see the sun, then it is not.
You can never really indicate "where" the sun is in such a diagram, you can only indicate the angle.
The shadows form a line pointing at the sun, yes, but it does not really tell you where the sun is, just where a line between you and the sun is.
At first I couldn't see the contrail only a beam coming from the west, that is what freaked me out so then I can't see reason because of lack of oxygen to the brain from freaking out! The shadow was lighter and pulsed forward, the sky was clear where the shadow formed. I am good with all that now. What is confusing is the sun is on the right hand side but may have been almost above me it was approx. 11.30am. The sun may have been higher than in the pic. Would a plane flying at 40k ft make a difference? The other problem with my thinking, I am remembering the shadow as going all the way out to sea before it filled with cloud however it may not have been that long before I saw the cloud so that may be where I am stuck. I have done another pic but the shadow probably wasn't that long, it kept growing as the cloud dropped in so in the end it was that long or longer. If you can explain the angle of the sun, then I am done, you will have debunked me! My head hurts! I can only see a week of archives on flightradar24 can anyone see further back, I only use the free the one. 25th April 2014 approx 11.30am Marcoola Queensland Australia. 
that's pretty specific. were you at an event or something where other people might have snapped a pic?
It was ANZAC Day 2014. There were many other aircraft in the sky.
https://www.flickr.com/photos/sampetherbridge/14022662353
It wasn't very dark I could only just make it out, if I slightly diverted my eyes I could see it better, like when you look at a sunset if you divert your eyes slightly the colours are more intense. Well that is what happens to me. It pulsed forward shrunk back a little then pulsed forward a bit. There was no reason for me to think it was a contrail shadow, that is why I am here to get myself debunked
Yes I have used it for star gazing also, thanks Pete. That is how it was with the contrail shadow as it got further east it got fainter. I am trying to think of ways to solve this puzzle.
That starts to make a bit more sense, comparing that track to the sun angle - the sun would be in the northeast, so, depending on the actual angle of view, it would appear to be behind the plane and could cast a shadow in front of it. Maybe a volumetric shadow would look right when viewed edge-on from the beach? I don't have the 3-D modelling skills to tackle that one!
)
Assuming the flight runs at the same time each day, then yes it may well do.
