Welcome Guest. Sign in or Signup

6 Answers

Magnetic bearing vs relative bearing?

Asked by: 26137 views Instrument Rating

How come one had to use the formula MH+RB=MB to dtermine the magnetic bearing? Why can't i just fly to the RB of the ADF to get to the station?

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.

6 Answers



  1. Boiler on Feb 02, 2013

    That equation is for a fixed card ADF. A fixed card ADF always shows North at the top and cannot be rotated. Therefore you need to use MH+RB=MB because you most likely aren’t heading North everytime you use your ADF.

    With a rotatable card ADF you can turn it to your airplane’s heading which eliminates the need for the math. In that case, you can just fly the RB to the station (plus or minus wind correction).

    +6 Votes Thumb up 7 Votes Thumb down 1 Votes

  2. Best Answer


    Wes Beard on Feb 02, 2013

    You can. If you place the needle of the ADF directly on top of the ADF you will track towards the station but not directly to it.

    Confused yet? In a no-wind situation, you will track directly to the station but with any wind you will make an arced path towards the station. Think about it. You set the ADF needle on top. The wind is blowing you off course so you correct by putting the needle back on top. The wind blows you off your new course and the process starts all over again. The instrument flying handbook has a good picture of this arc.

    The reason why we want to know the magnetic bearing is so we can track directly to the station with or without winds. In this scenario, we determine if we are still on the MB to the station and if not, we correct by changing our heading and then letting the ADF needle fall back towards the MB we want.

    The first method may make you fly into the side of a mountain. The second method will ensure you stay with the protected airspace for the airway or approach.

    +9 Votes Thumb up 9 Votes Thumb down 0 Votes



  3. wes eads on Feb 02, 2013

    Thanks guys both answers helped very much!!!

    +2 Votes Thumb up 2 Votes Thumb down 0 Votes



  4. Lucas on Feb 10, 2013

    Here is a youtube video that shows how easy an ADF really is (it also helps you answer all the questions on the Knowledge exams:

    http://www.youtube.com/watch?v=TEhpSIqwMe0&list=UU1AilFA8X2FR3FepaFvLBDw&index=8

    Cheers Lucas

    +6 Votes Thumb up 6 Votes Thumb down 0 Votes



  5. Larry Gordon Swift on Apr 08, 2014

    Don’t forget to set your directional gyro to your wet compass.

    +2 Votes Thumb up 2 Votes Thumb down 0 Votes



  6. LG Swift on Jul 12, 2017

    The reason you do not fly directly to the station, is because that may not be where you were going to, so please stop ending your sentences with a preposition, but thank you for the question.

    -11 Votes Thumb up 0 Votes Thumb down 11 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.