A picture of the 787 HUD (head up display) display taken today overflying the atlantic whilst overtaking a colleague who(m) flew 1000 feet above us on the north atlantic track system.
https://en.m.wikipedia.org/wiki/North_Atlantic_Tracks
Information that can be read from the HUD display.
37000 feet 280 kts
mach 0.86 (86% of the speed of sound)
Autopilot on
59 kts headwind
The flight path vector tells us which direction we are flying to, it is the aircraft symbol with the circle in it.
If we fly manually the circle tells us where the flight management system think we should be going and we then simply fly the aircraft symbol so it fits perfectly over the circle.
The flight path vector is a very handy tool as we can basically point it where ever we want to fly to and the aircraft will track towards that point.