Copyright © 2015  Grand Rapids Technologies, Inc.

Electronic Flight Instrumentation for Experimental Aircraft Since 1991

Attitude Indicator Options

The GRT EFIS attitude indicator has several options and settings for different flying styles and aircraft design characteristics. Here’s how you can set yours up to meet all of your needs.

Attitude Reference Index

The Attitude Reference Index is always the in the same position relative to the aircraft. The horizon line, pitch ladder and sky pointer move in relation to it, providing the indications of pitch, roll, and “which way is UP.”

The traditional attitude “bars” or “wings” can be replaced by a “nose” indicator (shown at right). This small indicator concisely displays the nose position of the aircraft relative to the horizon. To select Nose or Bars (wings):

  1. Access Set Menu > Primary Flight Display > Attitude Reference Index.
  2. Select NOSE or BARS.

Note: When ILS CDI crosshairs are displayed on the PFD, they replace the Attitude Reference Index. The crosshairs are always in the same position as the Attitude Reference Index, so they provide an effective replacement. Displaying both would unnecessarily clutter the screen.

Pitch Ladder Offset

The Pitch Ladder is a portion of the artificial horizon that depicts the pitch angle of the aircraft in relation to the horizon. It consists of horizontal lines above and below the neutral “zero-pitch” line, which is a thin white line stretched across the entire screen. Most of the ladder rungs are in 5-degree increments. Small horizontal lines below the zero-pitch line are in 1-degree increments for precise pitch control during landing approach. In the screenshot at right, the pitch angle of the aircraft is about 1 degree nose-low, as shown by the Attitude Reference Index (bars) crossing the first rung below the zero-pitch line. In the screenshot below it, note the white circle that marks the 90-degree pitch rung. This is visible during a loop or hammerhead.

To adjust Pitch Ladder Offset: During straight and level unaccelerated flight at the normal cruise power setting, the pitch ladder should be set so that the Attitude Reference Index is aligned with the zero-pitch line. The object is to set the pitch ladder for the easiest possible instrument scan during cruise.

  1. Access Set Menu page > Primary Flight Display.
  2. Scroll to Pitch Ladder Offset. Adjustments are made in positive or negative 1-degree increments; a positive setting will move the Attitude Reference Index up, and a negative setting will move it down.
  3. Adjust it in small increments until the Attitude Reference Index and the zero-pitch line are aligned during level normal cruise flight.

What NOT to do: Pitch Ladder Offset should not be used to compensate for the tail-down attitude of a taildragger on the ground. When you are on the ground in a taildragger, the view out the virtual EFIS window should look toward the sky, just as it looks out the windshield. Pitch ladder offset is ONLY for calibrating straight-and-level flight.

It should also never be used to adjust the attitude indication for varying airspeeds or other flight conditions. Once it’s set for your particular airframe/engine/propeller combo, the Pitch Ladder Offset should not normally be moved. Adjusting this for varying flight conditions can be dangerous when those conditions change again, potentially leading to spacial disorientation in instrument conditions. Paying attention to a consistently-placed pitch ladder indication will result in greater understanding of the pitch changes that occur with changing airspeeds, power settings and cargo loading.

Sky Pointer & Slip/Skid Indicator

The Sky Pointer is the white triangle in the middle of the bank indicator hash marks. This simply points UP at all times. If you roll inverted, it will point at the sky and thus appear as if it’s pointed at your floorboards. This is displayed as an aid for unusual attitude recovery and also serves as the bank angle pointer.

The small rectangular bar under the Sky Pointer is the Slip/Skid Indicator; thus, the modern instructor’s command for coordinated turns has become “Step on the Brick!”  At the request of some of our aerobatic HXr pilots, the traditional ball-type slip/skid indicator is now available as a choice on the HXr under the Set Menu > Primary Flight Display > Slip indicator. When “ball” is selected, the bar disappears and the electronic ball is prominently displayed above the heading indicator.