AMC OPS 1.500
En-Route – One Engine Inoperative
See JAR-OPS 1.500
1 The high terrain or obstacle analysis required for showing compliance with JAR-OPS 1.500 may be carried out in one of two ways, as explained in the following three paragraphs.
2 A detailed analysis of the route should be made using contour maps of the high terrain and plotting the highest points within the prescribed corridor’s width along the route. The next step is to determine whether it is possible to maintain level flight with one engine inoperative 1000 ft above the highest point of the crossing. If this is not possible, or if the associated weight penalties are unacceptable, a driftdown procedure should be worked out, based on engine failure at the most critical point and clearing critical
obstacles during the driftdown by at least 2000 ft. The minimum cruise altitude is determined by theintersection of the two driftdown paths, taking into account allowances for decision making (see Figure 1).
This method is time consuming and requires the availability of detailed terrain maps.
3 Alternatively, the published minimum flight altitudes (Minimum En route Altitude, MEA, or Minimum Off Route Altitude, MORA) may be used for determining whether one engine inoperative level flight is
feasible at the minimum flight altitude or if it is necessary to use the published minimum flight altitudes as the basis for the driftdown construction (see Figure 1). This procedure avoids a detailed high terrain contour analysis but may be more penalising than taking the actual terrain profile into account as in paragraph 2.
4 In order to comply with JAR-OPS 1.500(c), one means of compliance is the use of MORA and, with JAR-OPS 1.500(d), MEA provided that the aeroplane meets the navigational equipment standard assumed in the definition of MEA.
Driftdown is driftdown following thrust loss. Both the 1000' and 2000' clearances apply.
Letdown is an archaic name for a procedural approach.
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