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# Never heard of this before...

Australia, New Zealand & the Pacific Airline and RPT Rumours & News in Australia, enZed and the Pacific

# Never heard of this before...

9th Oct 2021, 12:16

Join Date: Nov 2014
Location: Melbourne
Posts: 37
Never heard of this before...

Hi Guys, I'm looking at the CASA Part 61 Syllabus both PPL/CPL and on the Navigation section in point (F) there is a mention of 'RELATIVE HEADING'. What is that? I have searched and searched on line and there is NOTHING about it.

"2.1 Form of the earth
2.1.1 Describe:
(a) the shape and rotation of the earth;
(b) latitude, longitude;
(c) the difference between true and magnetic north;
(d) how distance and direction are measured and applied to navigation;
(e) magnetic variation and compass deviation;

Any help is appreciated in explaining this mystery term.
9th Oct 2021, 19:20

Join Date: Nov 2006
Location: Auckland, New Zealand
Posts: 9

https://en.wikipedia.org/wiki/Bearing_(angle)

"In nautical navigation the relative bearing of an object is the clockwise angle from the heading of the vessel to a straight line drawn from the observation station on the vessel to the object.

The relative bearing is measured with a pelorus or other optical and electronic aids to navigation such as a periscope, sonar system, and radar systems. Since World War II, relative bearings of such diverse point sources have been and are calibrated carefully to one another. The United States Navy operates a special range off Puerto Rico and another on the west coast to perform such systems integration. Relative bearings then serve as the baseline data for converting relative directional data into true bearings (N-S-E-W, relative to the Earth's true geography). By contrast, Compass bearings have a varying error factor at differing locations about the globe, and are less reliable than the compensated or true bearings.

The measurement of relative bearings of fixed landmarks and other navigational aids is useful for the navigator because this information can be used on the nautical chart together with simple geometrical techniques to aid in determining the position of the vessel and/or its speed, course, etc.

The measurement of relative bearings of other vessels and objects in movement is useful to the navigator in avoiding the danger of collision.
• Example: The navigator on a ship observes a lighthouse when its relative bearing is 45° and again when it is 90°. He now knows that the distance from the ship to the lighthouse is equal to the distance travelled by the vessel between both observations."
9th Oct 2021, 20:08

Join Date: Nov 2014
Location: Melbourne
Posts: 37
Yeah, thanks Chris, I found that in two seconds too. That's not what I'm looking for. The term is RELATIVE HEADING.
9th Oct 2021, 21:17

Join Date: Jan 2007
Location: Sydney
Posts: 188
Whilst you're busy looking for that, maybe you can look for the GA PPRuNe forum where this thread should have been made.
9th Oct 2021, 23:36

Join Date: Oct 2007
Location: Aus
Posts: 1,679
It seems like a mistaken term that should be True/Absolute Heading or Relative Bearing. A relative bearing from the aircraft could be considered a relative heading to an object I suppose when overlaid on a DG or such. It's just not a term used.
10th Oct 2021, 01:14

Join Date: Oct 2000
Location: Sydney Australia
Age: 73
Posts: 113
A valid question on a site where more experienced pilots might be able to help. My Flight Navigator Licence notes don't help either.
10th Oct 2021, 02:02

Join Date: Mar 2005
Location: N/A
Posts: 4,541
Someone in CASA suffering brain fade? Don't know if it's still the case but decades ago for a ATPL(H) you had to study pressurisation.
10th Oct 2021, 12:57

Join Date: Mar 1999
Location: Brisbane, Qld, Australia
Age: 76
Posts: 1,369

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