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What’s the deal with the APR key?

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By Jim Pitman, CFI/DPE

FlywithJim.com

Revised: 17 August 2025

NOTE: The video version of this presentation is currently available at: https://www.patreon.com/posts/bonus-video-apr-136294178

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Disclaimers

  1. The information in this presentation is based on my personal experience and current understanding

  • GPS navigators vary greatly

  • Examples are based on modern Garmin GPS navigators.

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FlywithJim.com/G1000

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GPS vs. Autopilot

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The goal is to understand:

Activating a GPS Approach

vs.

Arming the Flight Director

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Common Misconception:

The APR key must be pressed to ensure�a GPS approach becomes active.

Reality:

The APR key has nothing to do with�activating GPS approaches.

One is a function of the Automatic Flight Control System (AFCS) and the other is a function of the GPS.

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An RNAV (GPS) approach becomes “active” when:

  • The aircraft is navigating to a fix (or between fixes) on an approach that is properly loaded in the active flight plan of the GPS navigator (magenta below the approach title).

  • All required RAIM, WAAS, and internal self-checks are successfully completed.

  • The aircraft is in the correct position and moving the �correct direction for the approach.

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An active RNAV (GPS) approach provides:

  • Proper waypoint sequencing.

  • Proper scaling (CDI sensitivity).

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With most modern GPS navigators,�this will all happen automatically.

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A GPS approach is set to become “active” when you see magenta below the approach title

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Now let’s talk about the oranges…

Automatic Flight Control System (AFCS)

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On many aircraft, the AFCS includes:

  1. Flight Director (FD)
  2. Autopilot (AP)
  3. Electric Pitch Trim
  4. Yaw Damper (YD)
  5. Control Wheel Steering (CWS)
  6. Electronic Stability and Protection (ESP)
  7. Underspeed Protection (USP)
  8. Overspeed Protection (OSP)
  9. Takeoff / Go-Around (TOGA)

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Levels of Automation

3. Flight Director (FD) with Autopilot (AP) engaged + FMS

2. Flight Director (FD) with Autopilot (AP) engaged

1. Flight Director (FD) only

0. No automation

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Flight Director (FD) vs. Autopilot (AP)

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  • The FD is the brains.

  • The AP is the muscle.

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The FD can be used without the AP (hand flying),�but the AP cannot be engaged without the FD.

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AFCS Status Box (AKA “Scoreboard”)

*** shows flight director modes ***

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No Automation

(Level 0)

Flight Director On

(Level 1)

Autopilot Engaged

(Level 2)

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The Approach (APR) Key

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The APR key arms the lateral and vertical modes of the FD to capture (this is not a GPS function)

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Putting it All Together

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RNAV (GPS)�RWY 05 at CGZ

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  • DVT to CGZ�
  • Via TFD

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  • Fly heading 150 to intercept the 170 bearing to TFD

  • Scoreboard

  • OBS mode

  • TERM annunciation

  • XTK distance

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  • No approach loaded in the active flight plan

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  • Pressed NAV to arm the FD to capture the GPS course�
  • This is a function of the FD, not the GPS

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  • GPS is now the active lateral mode (captured by the FD)

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  • OBS mode deactivated by the pilot (very important)

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  • Expect RNAV (GPS) Rwy 05 approach at CGZ�
  • Hold as published��

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  • Approach loaded, but not activated�
  • Wrong TFD!

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  • Entering the published hold

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  • The white flashing banner is your friend (Use it!)�

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  • Procedure turn complete

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  • Established on the inbound leg of the hold

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  • Press SUSP to continue holding�
  • The APR key has not been pressed

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  • APR has been pressed�
  • GP is armed to capture the glidepath when it centers

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  • This is a function of the FD, not the GPS

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  • Glidepath captured�
  • LPV annunciation (approach mode is now active)�
  • Another white flashing banner approaching the FAF

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  • New scenario: Vector to Final�
  • Cleared to intercept final, but not yet cleared for the approach

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  • Pressed the NAV key�

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  • Intercepted final�
  • Cleared for the approach

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  • Pressed the APR key to arm the FD to capture the vertical mode

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  • GP is the active vertical mode of the FD�
  • Follow the glidepath down to the DA

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Common Misconception:

The APR key must be pressed to ensure�a GPS approach becomes active.

Reality:

The APR key has nothing to do with�activating GPS approaches.

One is a function of the Automatic Flight Control System (AFCS) and the other is a function of the GPS.

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Resources

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