The instrument panels on old beater Cessnas, Pipers etc. have a 'slip ball' on the turn indicator which is basically a small ball in liquid. But that shows if

The instrument panels on old beater Cessnas, Pipers etc. have a 'slip ball' on the turn indicator which is basically a small ball in liquid. But that shows if the plane is laterally out of balance during a turn. It is about the only gravity based instrument on the aircraft (because ideally, you would want to keep a steady 1G straight towards the floor of the plane during a turn for passenger comfort). All other instruments that relate to orientation are gyroscope based, so they constantly reference a point in infinite space. When you are being thrown about in turbulence, or a tight turn, gravity based instrumentation will be all over the place and give false readings. Pretty much exactly why IFR (instrument flying) rated pilots are trained NOT to rely on the inner ear balance systems to know if they are flying straight and level etc. because the inner ear fluids can be easily tricked by standard flying manoeuvres into thinking you are in a screaming right hand dive when you are in a gentle left hand turn (if you don't have a visual reference to corroborate).