Aviation Auto Pilots Options

[SanderO]

I am familiar with marine recreational auto pilots and how they work. Marine navigation is a 2 navigational problem and considers the curve of the globe as flat for short distances. Long distance will require constant change of compass heading and trace a great circle as opposed to a rhumb line course. I understand how the heading to waypoint is calculated and updated and corrections applied to the rudder. Lots of number crunching and feedback.

Aviation however introduces a third axis - elevation. This is controlled by flaps and so forth, but not being a pilot I am not familiar with how this all works. I do understand that if you change the airfoil shape on one wing and not the other the plane will turn or the tail flap is moved to make a turn. I don't need a flying lesson but I can see the complexity in 3D autopilot control with so many means to control turns and climbs or descent.

My question is when did these auto pilot systems go operational for large planes?

Did this come after the DOD turned off selective availability of GPS or was it accurate enough with the SA on? Did / Do aviation GPS use DGPS or land stations for increased accuracy? Do the land based signals provide 2 D or 3 D data?

How are aviation auto pilots used? Are the navigation from waypoint to waypoint set by the pilot? Does this include altitude as well? Or are the waypoints established by ground based beacons?

Do pilots program headings or waypoints into their APs?

When were APs certified for landing commercial airliners?

[SanderO]

Amazed,

I am an architect and a sailor who has a sailboat and installed a "below decks" AP. I am not a pilot and was simply curious about the complexity and the vulnerability of these systems for use in programmed flight "paths" or "tracks" (don't know the aviation term or remote controlled ones.

I raise this issue because remote control and or "homing in" to a beacon has been mentioned to explain the plane behavior on 911.

I am trying to comprehend the technology involved and how reliable and accurate it would have been in 2001.