ATPL Performance: Legislation and Regulatory Framework
Regulatory Framework
Performance regulations ensure that aircraft can safely complete a flight even in the event of an engine failure at the most critical moment.
ICAO Annex 6
The International Civil Aviation Organization (ICAO) sets the standards in Annex 6 "Operation of Aircraft". It defines performance classes based on the number of engines and the aircraft's ability to continue flight after an engine failure.
EASA Regulations (CS - Certification Specifications)
In Europe, EASA defines the airworthiness codes:
- CS-25: Large Aeroplanes (Turbine powered, MTOM > 5,700 kg, or > 19 seats).
- CS-23: Normal, Utility, Aerobatic, and Commuter Aeroplanes (MTOM $\le$ 5,670 kg, $\le$ 19 seats).
Performance Classes
Operational regulations (like EU-OPS) divide aeroplanes into classes for performance purposes:
Performance Class A
- Aircraft: Multi-engine turbojets (any mass/seats) and multi-engine turboprops (if > 5,700 kg or > 9 seats).
- Requirement: Must be able to continue flight to a suitable aerodrome after an engine failure at any point (except during a very short period during take-off before $V_1$).
- Safety Level: Highest standard of safety.
Performance Class B
- Aircraft: Propeller-driven aeroplanes with $\le$ 9 seats and MTOM $\le$ 5,700 kg.
- Requirement: Generally single-engine or multi-engine aircraft that may not be able to maintain altitude after an engine failure. In case of engine failure, a forced landing might be necessary.
- Safety Level: Lower than Class A; relies on the ability to reach a landing site.
Performance Class C
- Aircraft: Large reciprocating (piston) engine aeroplanes (mostly legacy aircraft like DC-6, Constellation).
- Requirement: Similar to Class A but with slightly less stringent climb gradients.
Airworthiness vs. Operations
- Airworthiness: Ensures the aircraft is built to perform (e.g., can climb at 2.4% gradient with one engine inoperative).
- Operations: Ensures the aircraft is operated safely in specific conditions (e.g., checking if that 2.4% gradient clears the mountains on a specific departure).