(YouTube) A crop duster's nose mounted display.
It looks like a poor man's HUD to keep the display and the outside view at roughly the same focus distance, but what is its function?
Using the main unit, different information can be displayed on the lightbar:
Basic data can also be shown (e.g. airspeed) See this video. The indicator itself:
Aerial dusting navigation can follow differently formatted routes, the most common being the racetrack. Take a plot of land of irregular format, place both straightaways of an oval racetrack on top of it and every pass is one wingspan to the right or left of the previous one. Basically, you must know at all times if you are flying straight and the same distance from the previous pass, so as to spray every plant, double spraying a bare minimum of them (overdosing pesticides causes toxic effects to plants, product waste and loss of profit).
This simple and efficient display tells the pilot that she is on course. It is pretty simple, but must be very discreet and in the line of sight so that the pilot, who is flying at 120 kmh or less at an altitude of 3 to 5 meters does not lose her environment from sight for even a fraction of a second.
I don't know how many funerals for dusting pilots you have attended, but i don't care to go to another. It is a dangerous, dangerous profession (and i'm not even mentioning the pesticides themselves - ever been inside a duster cabin?). Therefore, in these conditions, the pilot simply cannot look down at her console, all navigation correction must be done while looking ahead.
There is no margin for error in cropdusting. This is anything but a "poor man's" solution, it is a simple and efficient rustic navigational device with no frills, that works in any condition.
If you care to study a bit, read about Embraer's (Niva) Big Ipanema (Ipanemão) duster.