An Engine Out Procedure (EOP) is a custom-designed, lateral flight path “escape route” to provide a climb departure designed to minimize obstacle and terrain constraints. The EOP is designed to be used only in cases where an engine failed during the takeoff runway. The EOP is not a Standard Instrument Departure (SID), which is designed for the normal, all engine operating (AEO) scenario. While an EOP may initially follow a SID path, this is not always the case, especially if terrain requirements dictate otherwise.
When selecting an airport and a runway, most runways will offer a default straight-out option (”fly runway heading”). Terrain and obstacles along the runway heading path are used in the runway analysis to determine a MTOW that ensures clearing all terrain and obstacles along this path. Since the straight-out is a non-optimized flight path, it typically results in the lowest MTOW solution.
Beyond the straight-out option, many runways include one or more custom-designed EOPs with the goal of maximizing takeoff weight for an OEI climb. These EOPs are designed to minimize terrain and obstacle constraints, while also keeping flyability and pilot workload in mind. Two types of EOPs can be found for any given runway - Jeppesen EOP and one or more RNAV EOPs.
Jeppesen EOPs were designed with Part 121 (airline) operations in mind and rely heavily on VOR and DME use. These EOPs have existed for many years and are in use by many airlines. RNAV EOPs, on the other hand, are designed by ForeFlight and make use of various navigation aids, including GPS waypoints. The RNAV EOPs will typically provide the highest MTOW solution as they are purpose-built to minimize climb constraints. When possible, they will also follow initial SID procedures to simplify a pilot’s workload, which may already have that SID loaded in the FMS.
When viewing the list of available straight-out and EOPs, the MTOW is calculated and displayed for each EOP, allowing quick and convenient comparison of expected performance for each EOP.