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Figure D6: Continuing Point (B) Located Before the No-Return Point (A) 

Figure D7: Continuing Point (B) Located After the No-Return Point (A) 

2.2.3. Diversion Airfield 

“JAR-OPS 1.500 

(a) The net flight path must have a positive gradient at 1,500 ft above the aerodrome where the landing is assumed to be made after an engine failure.“ (Figure D8) 

The route study must indicate the different possible en route diversion airfields associated with the various diversion scenarios. The net flight path gradient should be positive at least at 1,500 feet above the airport where the landing is assumed to be made. For that purpose, fuel jettisoning can be considered, when the system is available. 

Moreover: 

“JAR-OPS 1.500 (c)(4) The aerodrome where the aeroplane is assumed to land after engine failure must meet the following criteria: 

The performance requirements at the expected landing mass are met 

Weather reports or forecasts, or any combination thereof, and field condition reports indicate that a safe landing can be accomplished at the estimated time of landing” 

Alternate airports must be clearly specified in the dispatch or flight release, and must meet the prescribed weather minimums for the approach category. If these minimums are not met, the associated diversion procedures are no longer possible. 

2.3. Twin Engine Aircraft 

2.3.1. 60 Minute Rule 

“JAR-OPS 1.245 

(a) Unless specifically approved by the Authority […], an operator shall not operate a two-engined aeroplane over a route which contains a point further from an adequate aerodrome than the distance flown in 60 minutes at the [approved] one-engine-inoperative cruise speed”. 

When at least one route sector is at more than 60 minutes’ flying time, with one engine inoperative from a possible en route diversion airfield (Figure D9), the airline needs  specific approval, referred to as ETOPS1 approval. ETOPS is dealt with in an Airbus-specific brochure entitled: “Getting to Grips with ETOPS” and will, therefore, not be detailed in this manual. 

2.4. Four Engine Aircraft 

2.4.1. 90 Minute Rule 

“JAR-OPS 1.505 

(a) An operator shall ensure that at no point along the intended track will an aeroplane having three or more engines be more than 90 minutes, at the all-engines long range cruising speed at standard temperature in still air, away from an aerodrome at which [landing] performance requirements are met, unless it complies with [specific rules]”. 

1 ETOPS = Extended range with Twin-engine aircraft OPerationS 

These specific rules, developed later, assume the simultaneous failure of two engines, which has to be considered for dispatch, as soon as one route sector is at more than 90 minutes’ flying time, with all engines, from a possible en route diversion airfield. 

“JAR-OPS 1.505 

(c) The two engines are assumed to fail at the most critical point of that portion of the route where the aeroplane is more than 90 minutes [flying time] away from [a possible diversion] aerodrome.” (Figure D10). 

2.4.2. Obstacle Clearance – Two Engines Inoperative 

2.4.2.1. Lateral Clearance 

The regulations define the corridor width within which obstacles must be taken into account, as follows: 

“JAR-OPS 1.505 

(b) The two engines inoperative en-route net flight path data must permit the aeroplane to continue the flight, in the expected meteorological conditions, from the point where two engines are assumed to fail simultaneously, to an aerodrome at which it is possible to land, […] clearing all terrain and obstructions along the route within 9.3 km (5 nm)1 on either side of the intended track. […] If the navigational accuracy does not meet the 95% containment level, an operator must increase the width margin […] to 18.5 km (10 nm)2.” 

1 FAA: 5 statute miles 2 JAA rule not valid for FAA 

2.4.2.2. Vertical Clearance 

Vertical clearance shall always be understood as a margin between the two engines’ inoperative net flight path and the obstructions. The two engines inoperative en route net flight path shall be determined from the Aircraft Flight Manual, and must take into account the meteorological conditions (wind and temperature) prevailing in the area of operations, as well as the use of ice protection systems, if required. 

“JAR-OPS 1.505 The net flight path must clear vertically, by at least 2,000 ft all terrain and obstructions along the route within [the prescribed corridor].” 

2.4.3. Diversion Airfield – Two Engines Inoperative