Welcome Guest. Sign in or Signup

2 Answers

Baro setting on altimeter

Asked by: 7391 views
General Aviation

My plane is set on autopilot and I receive an updated altimeter setting.  I reset the aircraft altimeter, but fail to reset the baro setting on the autopilot.  What would happen?

Would the autopilot be following the wrong pressure level causing my aircraft to be higher or lower that what’s being displayed on the altimeter?  



Ace Any FAA Written Test!
Actual FAA Questions / Free Lifetime Updates
The best explanations in the business
Fast, efficient study.
Pass Your Checkride With Confidence!
FAA Practical Test prep that reflects actual checkrides.
Any checkride: Airplane, Helicopter, Glider, etc.
Written and maintained by actual pilot examiners and master CFIs.
The World's Most Trusted eLogbook
Be Organized, Current, Professional, and Safe.
Highly customizable - for student pilots through pros.
Free Transition Service for users of other eLogs.
Our sincere thanks to pilots such as yourself who support AskACFI while helping themselves by using the awesome PC, Mac, iPhone/iPad, and Android aviation apps of our sponsors.

2 Answers

  1. John D. Collins on Feb 11, 2011

    It is a good question, but the answer is dependant on which autopilot.  Many autopilots do not have a Baro input and hold the altitude based on the pressure at the time it was engaged.  Autopilots such as the Garmin GFC700 and the Bendix King KFC225 will automatically follow the changes made in the baro setting for the altimeter. If your autopilot doesn’t adjust the altitude when the barometer changes on the altimeter, then you have to make the change manually and reestablish the altitude that the autopilot is holding.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes

  2. Kent Shook on Feb 12, 2011

    Student Pilot,
    If you’re flying an airplane with an autopilot such as the KAP 140 that has a Baro setting that’s separate from the altimeter setting, and you don’t change the Baro setting on the autopilot, the autopilot will be flying at the wrong altitude. However, as long as you did update the setting on the altimeter itself, it will still read correctly and you’ll be able to easily tell that you’re not quite at the right altitude.
    Usually, this is not an issue if you simply forget to do the reset in flight because you won’t be changing it much, and .01 on the altimeter roughly corresponds to a 10-foot change in altitude. However, if you forget to set the Baro setting on the autopilot prior to flight, it may be significantly different from the actual altimeter setting, and level you off somewhere other than where you’re expecting – So get in the habit right away of changing ALL of the altimeter settings, even if you’re not using the autopilot. Some airplanes (for example, a Cessna or Diamond Star that has a G1000 system but a King autopilot) have THREE places to change the setting: One on the G1000, one on the autopilot, and one on the backup altimeter. Make sure you know where your airplane needs that setting, and change every one of them every time.

    +1 Votes Thumb up 1 Votes Thumb down 0 Votes

The following terms have been auto-detected the question above and any answers or discussion provided. Click on a term to see its definition from the Dauntless Aviation JargonBuster Glossary.

Answer Question

Our sincere thanks to all who contribute constructively to this forum in answering flight training questions. If you are a flight instructor or represent a flight school / FBO offering flight instruction, you are welcome to include links to your site and related contact information as it pertains to offering local flight instruction in a specific geographic area. Additionally, direct links to FAA and related official government sources of information are welcome. However we thank you for your understanding that links to other sites or text that may be construed as explicit or implicit advertising of other business, sites, or goods/services are not permitted even if such links nominally are relevant to the question asked.