What’s Up With
Heading?
Heading can mean different things when pilots and controllers talk
WE ALL LEARNED IN ground school that heading is a number on the
magnetic compass. In strict navigation terminology the heading is
where the airplane is pointed referenced to the magnetic field
around it. Simple, right? Not always.
The problem is that sometimes when pilots and controllers talk,
the word heading can mean the compass heading, but it can also
mean desired track or course. Most of the time pilots know which
information a controller wants or what instruction he is issuing, but
not always.
HORIZONTAL SITUATION INDICATOR (HSI)
1
7
6
2
2
3
4
5
1. Heading Select Bug 2. Glideslope Pointers 3. Course Deviation Bar 4. Course Deviation Scale
5. Glideslope Deviation Scale 6. TO/FROM Indicator 7. Course Select Pointer
Not that long ago most of us could know
only our mag heading with reasonable certainty. Unless we were flying along a VOR
radial our actual track—path across the
ground—was only an estimate. Remember
the E6-B computer with its pencil dots and
dials that made it easy to solve the wind triangle problem? All of that math was
designed to convert a magnetic heading into
a course corrected for wind drift—a desired
track. Or more often we used the E6-B to
transform a line on the chart—a desired
track—into a heading to fly to maintain that
track. But the key word here is “estimated”
because the wind was always an estimate, so
that made any solution to the wind triangle
problem no better than a bit of a guess.
However, controllers had the opposite
information based on their radar presentation. The radar can only show controllers an
airplane’s track over the ground, leaving the
controller with no information on the heading the pilot is flying. Pilots knew heading,
and controllers knew only track, so it was
natural for controllers to ask for, or assign,
heading because that’s all a pilot could fly,
and it was the information the controller
didn’t have.
Now with the proliferation of GPS navigators the navigation situation has been
turned on its head. Controllers still only can
see ground track and groundspeed, but in
the cockpit we can see our heading, of
course, along with desired track, cross track
error, track angle error, wind direction, and
speed and bearing to the waypoint, all with
great precision.
NAVIGATION TERMINOLOGY
First, let’s review basic navigation terms,
because I don’t think they are well understood by pilots. GPS terminology is
certainly not completely explained in most
