Fascinating photo, Spaz. I'd like that headrest on my next long-haul flight as it looks very comfortable.
Complete guess - but it looks as if, at any conceivable head angle and location that involves the hereinbeforementioned head remaining attached to the rest of the pilot, the headrest occludes some of the glass. Which makes the point of having glass back there a little hard to understand.
Also, that headrest - which
inter alia contains two airbag thingies that catch and decelerate your head as the airblast pushes it back, because the helmet means that your head is snapping forward and down on ejection - looks a bit bigger than the catcher's-mitt device on the rival Goodrich ACES 5.
http://www.goodrich.com/gr-ext-templ...%20website.pdf