Flight Training Advice And Analysis
There are some simple rules governing the behavior of aircraft flying near each other. It is important to understand who has the right-of-way.
Airplane instruments and systems are usually as simple as possible. This is because simple systems will break less often. The magnetic compass is one of the simplest instruments there is.
A compass is made up of a housing with a lens on the front and a vertical line (called a lubber line) inside the glass representing the current heading. Inside of the housing, there is a liquid with the compass “float” suspended on a pivot. The float itself has the sensing magnet inside and markings for every heading. As the aircraft turns the float spins and indicates the planes heading along the lubber line.
There is also a second adjustable magnet in the bottom of the unit to correct for errors.
Finally, most magnetic compasses will have a light mounted above the lens so it can be viewed at night.
The construction of the compass causes a few problems when reading it during turns and changes in speed. There are 3 basic types of errors.
This is the simplest type of error. In turbulence, the indicator may bounce around because it is floating. If the compass is moving around continuously don’t expect to get a precise heading from it.
To determine your heading during turbulence, look for the midpoint or average of the oscillations.
When banking the compass will turn to follow the vertical component of the earth’s lines of magnetic flux. In other words, the compass is drawn down towards the earth.
So if you are heading North and you start a turn the compass will try to point down towards the low wing. As the magnet is drawn down it will turn the indicated magnetic heading indicating a turn in the wrong direction.
Conversely, if you begin a turn while heading South the compass will indicate a turn in the right direction but it will turn more than your actual heading.
During turns, the compass lags when you are heading North and leads when you are heading South.
Remember OSUN or UNOS.
When the aircraft accelerates the inertia of the heavy magnet causes the compass to rotate. It pulls towards the Northerly heading. Conversely, when slowing down the magnet pulls the card towards a southerly heading as it is moved forwards. This effect is most prominent when heading East or West and doesn’t have any effect when heading North or South.
Remember ANDS.
An aircraft is full of magnetic parts and flowing electrical currents that can interrupt the magnetic compasses ability to sense magnetic North. The adjustable compensator is set by a technician to account for these errors.
However, the compensator can’t fix this completely so a compass card is included with deviations corrections. When flying a magnetic heading read the heading you want under “For” and then turn to the indicated heading under “Steer”. Don’t forget about this when setting your directional gyro to match your compass.
There are several maneuvers to learn in order to become a private pilot. Turns around a point is the most basic of the ground reference maneuvers.
It is simply a turn flown around some point on the ground. It is common to use a prominent building or intersection of a road as the point.
Maneuvering speed is affected by the weight of the airplane.
If the plane is at max gross weight, it has a better, higher, maneuvering speed.
Conversely at a lower weight maneuvering speed is lower, meaning that you need to fly slower to get safely below maneuvering speed.
Yes, this is one of the few aircraft performance speeds that actually improves with a higher weight! Continue reading “Maneuvering Speed Part 2: Determining Maneuvering Speed for your Plane.”