Avionics News February 2023 - 51

way you or the aircraft are pointed - east in the example
above. Course is the direction you or the aircraft are
actually traveling; in this case, northeast, or 45 degrees.
For any of our navigation systems, we need to understand
there is a difference between heading (where we are
pointing) and course (where we are going). If there was
no wind, then heading and course would be the same.
Still air, or no wind, is a rare condition at altitude, so
we consider it normal for heading and course to be two
different things.
Since aircraft navigate in a three-dimensional
environment, it is handy for the technician to understand
altitude. Aircraft fly at altitudes defined by their height
above the mean sea level. An important altitude is the
above ground level altitude. The difference between the
two altitudes can vary greatly. An aircraft flying at 1,000
feet MSL would be at the same altitude AGL when flying
over the ocean. At the Williamsport Regional Airport
in Pennsylvania, this same aircraft flying at 1,000 feet
MSL would only be at 500 feet AGL. At the Roben-Hood
Airport in Big Rapids, Michigan, 1,000 feet MSL would
be 10 feet off the ground, or 10 feet AGL. Airplanes
flying above 18,000 feet MSL will set their altimeters to
a standard setting. They are flying pressure altitude. As a
result, as they fly across the country, their altitude MSL
will gradually change higher and lower as they pass over
high- and low-pressure weather areas.
With these basic map skills in mind, over the next
several months, we can discuss different ways to measure
distance, hold a course, find a runway, and more. Next
month, we will introduce a system the Federal Aviation
Administration has designated as part of the minimum
operational network called the very high frequency
omnirange. We will also introduce a direction finding
system known as the automatic direction finder. These
will all be overviews; those wishing to earn a DNS
endorsement will need to put time into studying materials
outside of this magazine. q
Not for wanna-be's or used-to-be's.
AVweb:
Over 230,000 news-hungry
subscribers,
More than 82% are owner-pilots
who fly and buy.
AVwebFlash and AVwebBiz e-newsletters are
published four days weekly, providing the
latest GA news to active owner-pilots who
want to keep up with the latest industry
news, new products and technology-delivered
to their iPhones, iPads, Androids, tablets
and desktops.
AVweb advertisers including Avidyne,
Aspen Avionics, BendixKing, Bose, Flightcom,
ForeFlight and Sennheiser know that Avweb
delivers.
That's because AVweb subscribers are techsavvy,
owner-pilots who fly and buy-not
wanna-be's or used-to-be's.
They want news they can use: expert video
in-flight demos, new product analysis and
comparison, industry commentary and blogs,
and now, features about proficiency, safety
and the emergence of restored, rebuilt and
remanufactured aircraft.
You read AVweb, your customers read AVweb.
It's free and it's fast.
Find out how AVweb advertising, webinars
and videos can deliver customers for you.
Ask about special ad rates for AEA members.
Call Tom Bliss at 602-625-6815.
Or, email: tom@avweb.com.
The world's premier independent GA news source.
avionics news * february 2023 51
http://www.avweb.com
Avionics News February 2023

Table of Contents for the Digital Edition of Avionics News February 2023
