Editing Autopilot (section)

===Computer system details===
The hardware of an autopilot varies between implementations, but is generally designed with redundancy and reliability as foremost considerations. For example, the Rockwell Collins AFDS-770 Autopilot Flight Director System used on the [[Boeing 777]] uses triplicated FCP-2002 microprocessors which have been formally verified and are fabricated in a radiation-resistant process.<ref>{{cite web | url=http://www.rockwellcollins.com/ecat/at/AFDS-770.html | title=Rockwell Collins AFDS-770 Autopilot Flight Director System| publisher=Rockwell Collins | date=3 February 2010 | access-date=14 July 2010| archive-url= https://web.archive.org/web/20100822151603/http://www.rockwellcollins.com/ecat/AT/AFDS-770.html| archive-date= 22 August 2010 | url-status=live}}</ref>

Software and hardware in an autopilot are tightly controlled, and extensive test procedures are put in place.

Some autopilots also use design diversity. In this safety feature, critical software processes will not only run on separate computers, and possibly even using different architectures, but each computer will run software created by different engineering teams, often being programmed in different programming languages. It is generally considered unlikely that different engineering teams will make the same mistakes. As the software becomes more expensive and complex, design diversity is becoming less common because fewer engineering companies can afford it. The flight control computers on the [[Space Shuttle]] used this design: there were five computers, four of which redundantly ran identical software, and a fifth backup running software that was developed independently. The software on the fifth system provided only the basic functions needed to fly the Shuttle, further reducing any possible commonality with the software running on the four primary systems.