The Flight Director:

The Flight Director (FD) is one of modern avionics greatest achievements; simply put, the FD provides the pilot with clear and unambiguous pitch and bank guidance for any programmed maneuver via moving icons overlaid on the Artificial Horizon.

The FD itself is a computer that can be selected ON or OFF and uses data from the aircraft’s Autopilot (or the FMS in more advanced aircraft) to drive guidance elements on the Artificial Horizon, right in front of the pilot

Traditionally, on most aircraft developed in the 60s and 70s the FD comprises two narrow bars (one horizontal and one vertical) which when activated form ‘crosshairs’. When the ‘crosshairs’ are centered, then the aircraft is following the ‘commanded’ pitch and bank. This example shows a 737-200’s Artificial Horizon with its crosshairs centered:

This style of FD was very popular in the electro-mechanical Artificial Horizons fitted to airliners until the beginning of the ‘EFIS / CRT’ era about 15 years ago; the computing power required to drive the crosshairs is relatively simple, as are the systems that actually motivate the ‘needles’. Many airlines chose to keep the ‘crosshairs’ style of FD when transitioning to ‘EFIS / CRT’ based systems to simplify the transition.

As computing power, and the complexity and reliability of electro-mechanical systems grew, US manufacturer Collins Avionics developed an idea for a new, more capable, articulating FD which became known as the ‘Inverted V-Bar’ FD (sometimes referred to as the ‘Collins FD-108’). In this design one element remained fixed in the center of the Artificial Horizon, whilst the other (known as the ‘moving’ element) moved up and down in the vertical plane commanding a climb or descent, whilst tilting left or right to command a turn. This example shows the V-bar FD on a 747-400 PFD:

Although the V-bar FD is found on both conventional and electronic Artificial Horizons it is fast becoming the standard of choice for EFIS / CRTs in new aircraft on everything from general aviation to the latest airliners.

Please review the following graphics which demonstrate both ‘Commanded’ and ‘Executed’ maneuvers for both ‘Crosshairs’ and ‘V-Bar’ FDs:

On a closing note, remember that the FD is ONLY as good as its information source. Testing has demonstrated that the optional MCP available from PFD is much more capable and accurate than the guidance provided by FS-98’s default autopilot. Whilst our FDs have been designed to work with EITHER FS-98’s Autopilot or PFD’s MCP; we would strongly recommend the MCP option for serious IFR flying, or ‘professional’ training purposes.