Cooper Harper Rating

Cooper-Harper Rating (flight-mechanics/handling-qualities/cooper-harper-rating)

Use when the task is assigning a Cooper-Harper handling qualities rating to an aircraft from a piloted evaluation, classifying the rating band, or planning the flight test procedure that collects the ratings.

Domain quick reference

• The Cooper-Harper scale runs 1 (excellent) to 10 (uncontrollable). The rating is assigned by the pilot in the loop after flying a defined evaluation task, not by the engineer on the ground.
• Decision tree (paraphrase of the standard rating procedure):
  1. Is the aircraft controllable? No gives 10 (uncontrollable).
  2. Is adequate performance attainable with the required tolerances? No gives 7-9 (deficiencies require improvement).
  3. Is the aircraft satisfactory without improvement? Yes gives 1-3, graded by the pilot compensation needed; No gives 4-6 (deficiencies warrant improvement), graded by compensation.
• Rating bands: 1-3 satisfactory without improvement, 4-6 deficiencies warrant improvement, 7-9 deficiencies require improvement, 10 uncontrollable.
• Compensation anchors on the satisfactory side: none gives 1, negligible gives 2, minor gives 3. Worked example: controllable, adequate performance, desired tolerances, no compensation = 1.
• Compensation anchors on the warrant-improvement side: minor gives 4, moderate gives 5, considerable gives 6. Worked example: controllable, adequate performance, adequate tolerances, considerable compensation = 6.
• Compensation anchors on the require-improvement side: minimal gives 7, considerable gives 8, extensive or intense gives 9. Worked example: controllable but adequate performance not attainable, extensive compensation = 9.
• Handling qualities levels (MIL-STD-1797A framing): ratings 1-3 are Level 1 (satisfactory), 4-6 Level 2 (adequate), 7-9 Level 3 (controllable), 10 uncontrolled. Certification flight characteristics work normally demands Level 1 for the operational flight envelope.
• Flight test procedure: brief the task and the desired and adequate tolerances before flight, fly the maneuver, let the pilot assign the rating immediately after each run, record deficiencies and pilot comments, and repeat for scatter.

Workflow

1. Define the evaluation task and write the desired and adequate tolerances before the first flight: the rating is meaningless without a defined task and measurable tolerances.
2. Confirm the aircraft is controllable through the maneuver with cooper_harper_rating(controllable=False, ...), which returns 10.
3. Check whether adequate performance is attained; if not, the rating lands in the 7-9 band graded by the compensation required to retain control.
4. Check whether the aircraft is satisfactory without improvement; if yes, grade 1-3 by the pilot compensation needed for desired performance.
5. Otherwise grade 4-6 by the compensation needed for adequate performance.
6. Classify the result with rating_band and handling_qualities_level, and check the level against the certification requirement (Level 1 for the operational envelope).

Pitfalls

• Routing stability derivative questions here: neutral point, static margin, and stability derivative sizing belong to longitudinal-stability; the Cooper-Harper rating is a pilot judgment of the closed-loop task, not a derivative calculation.
• Routing dynamic response questions here: short period and dutch roll damping, natural frequency, and eigenvalue analysis belong to dynamic-stability; the rating summarizes the piloted experience, it does not replace the mode analysis.
• Routing trim questions here: trim forces, trim control deflections, and trim speed analysis belong to trim-analysis; a heavy but achievable trim condition may lower a rating but is not itself a rating.
• Routing control power questions here: hinge moments, control surface effectiveness, and control authority belong to control-surface-effectiveness; the rating captures the perceived workload, not the aerodynamic authority numbers.
• Confusing 10 with 9: 10 means control is lost during the task (uncontrollable); 9 means the aircraft is controllable but only with intense or extensive compensation.
• Mixing the tolerance classes: desired tolerances grade the 1-3 band, adequate tolerances grade the 4-6 band; rating with adequate tolerances against a desired-performance question shifts the band.
• Rating the pilot instead of the aircraft: the scale rates the handling qualities of the vehicle for the task, not the skill of the pilot flying it.
• Averaging ratings across different tasks: each rating is valid only for the task and tolerances it was collected under; a single averaged number hides the task dependence.
• Issuing ratings without a defined task: a Cooper-Harper rating without stated desired and adequate tolerances cannot be verified and should be treated as an opinion, not an evaluation result.

Behavior contract (gate 3)

The decision tree, band classification, and handling qualities level mapping is exercised by the gate 3 contract test: scripts/test_cooper_harper_rating.py against scripts/cooper_harper_rating_logic.py (stdlib unittest, offline). Run: python3 scripts/test_cooper_harper_rating.py

Compliance

• Standards referenced, not reproduced: FAR-25 and CS-25 flight characteristics requirements frame the handling qualities assessment for transport aeroplanes; the Cooper-Harper scale itself is the common pilot-rating methodology of Cooper and Harper (1969), summary-only per standards-map.yaml.
• compliance: STANDARDS-REF, gated: false.