Extended Range Operations
Extended Diversion Time Operations (EDTO)
Extended Range Twin-engine Operations (ETOPS) regulations have been in place since 1985. They were introduced to ensure that twin-engine airplanes operate safely at levels similar to their three and four-engine counterparts. As airplane reliability and range improved over the years, it became evident that all multi-turbine engine aircraft were venturing further from nearby alternate airports. This realization led to a review of ETOPS regulations.
In 2012, after extensive discussions about international flight facilitation, changes were made to ICAO Annex 6 Part 1 under Amendment 36. This change introduced Extended Diversion Time Operations (EDTO) to replace ETOPS. While the EDTO regime has gained acceptance, the term ETOPS is still used by some, including the FAA, which redefined it as ‘Extended range OPerationS’ instead of ‘Extended range Twin OPerationS’. The European Union Aviation Safety Agency (EASA) continues to use the original definition of ETOPS alongside ‘LROPS’ for three and four-engine aircraft.
The new guidance in Annex 6, particularly Attachment D, outlines extended range operations for all turbine-engine planes flying more than 60 minutes from an alternate airport. A key distinction is made between operations that do not exceed a defined ‘Threshold Time.’ This Threshold Time represents the maximum time an operator can fly from any point on a route to an en-route alternate airport without requiring EDTO approval.
ICAO converts Threshold Time into distance based on one-engine-out speed for twin-engine aircraft and all-engine-operating speed for those with more than two engines. However, the FAA bases EDTO approvals on one-engine-out speed for all aircraft types. Non-EDTO flights must still adhere to additional flight planning principles beyond standard operations, including operational control, identifying alternate aerodromes, and ensuring availability of these alternates if needed. Training programs for personnel should also include relevant content.
EDTO flights require explicit approval, similar to the previous ETOPS system, and involve both aircraft design and operational requirements. The safety of EDTO operations hinges on two main principles: designing reliable engines and systems to avoid in-flight diversions and implementing robust operational systems to manage any necessary diversions safely.
To ensure compliance, an Aeroplane Type Design Assessment must evaluate the aircraft’s airframe and engine combination for compatibility with extended range operations. This assessment is validated by the Type Design Authority. Additionally, airlines must obtain Operational Safety Approval from the State of the Operator to confirm that their EDTO practices align with safety standards.
Each EDTO Type Design or Operational Approval introduces a Maximum Diversion Time, allowing operators to define approved areas for operations. If this Maximum Diversion Time exceeds 180 minutes, stringent requirements apply, such as maintaining a low In-Flight Shut Down (IFSD) rate for the specific aircraft type. ICAO guidelines stipulate that aircraft cannot operate on routes where diversion times exceed established thresholds without proper approval.
The EDTO Operational Approval Process requires applicants to define EDTO routes, establish maintenance procedures, and identify adequate en-route alternate airports. They must also determine necessary diversion times and engine inoperative planning speeds, ensuring a reliable communication method during flights. Before issuing approvals, states must verify that maximum diversion times do not exceed critical limitations identified in the Aircraft Flight Manual (AFM).
The continued validity of EDTO approvals relies on reporting any relevant events that could affect flight safety. These events may arise from technical issues or non-technical circumstances. Awareness of these occurrences helps manufacturers and certifying authorities maintain oversight and ensure continued airworthiness.
Furthermore, ICAO recommends that States consider allowing operations to continue on previously approved routes even after established thresholds if safety assessments support it. This flexibility is essential for adapting to evolving operational realities in aviation.
