Spatial Apperception: Reading Bank and Pitch from a Windscreen View
A candidate is working an untimed Spatial Apperception practice set. In frame A the true horizon crosses the windscreen at about 20 degrees to the horizontal, with the right end of the horizon as the high end: sky fills the upper-left of the view and ground the lower-right. The horizon crosses the vertical centerline of the windscreen well below the middle, so most of the view is sky. In frame B the horizon is perfectly level but again sits low in the windscreen. The set uses the convention that the horizon in the forward view rotates opposite to the aircraft's roll, and that vertical displacement of the horizon indicates pitch.
1. State the aircraft's approximate bank angle and direction and its pitch attitude in frame A, and identify which cue carries which piece of information.
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Bank: the horizon is rotated about 20 degrees, right end high. Under the stated convention the horizon rotates opposite the aircraft's roll, so a high right end of the horizon means the right wing is low - a bank of roughly 20 degrees to the right.
Pitch: the horizon sits well below the windscreen centre, so most of the view is sky. Seeing more sky than ground means the nose is above the horizon - nose-up pitch.
Cue separation: rotation of the horizon encodes roll only; vertical position of the horizon encodes pitch only. Frame A is therefore a right bank of about 20 degrees while climbing or holding a nose-high attitude.
2. Describe how the attitude indicator should look in frame A and in frame B, and state how frame B differs in attitude.
Read the worked answer
Frame A: the horizon bar is tilted about 20 degrees with its right end up - blue sky biased to the upper-left of the instrument, brown ground to the lower-right - and the bar sits below the centre of the instrument, showing a large arc of blue above it. That is a right bank with the nose up.
Frame B: the bar is level, so the wings are level, but it is still displaced downward, so the nose is still up. Frame B is wings-level, nose-high.
The difference between the frames is pure roll: the pitch cue is unchanged, the bank cue has gone to zero.
3. Another candidate argues frame A shows a left bank 'because the horizon drops away on the left'. Diagnose the error and state the general rule that prevents it.
Read the worked answer
The error: the candidate is reading the low end of the horizon as the low wing. That inverts the relationship.
Why it inverts: the horizon appears to rotate opposite the aircraft's roll. When the right wing goes down, the pilot's whole frame of reference rolls with it, and the outside world appears to rotate the other way - so the horizon's right end climbs up in the view while the ground, which is where the low wing points, occupies the lower-right.
General rule to apply every time:
- Find the high end of the horizon.
- The wing on the opposite side is the low wing; that is the direction of bank.
- Confirm with the ground: ground occupies the side the low wing points toward.
Applying the rule to frame A: high end right -> left wing high, right wing low -> right bank. The candidate's shortcut ('the horizon drops on the left, so it is a left bank') collapses under step 2.