AC 120-42B ETOPS and Polar Ops - Code7700

6/13/08 AC 120-42Bminutes, the requested level of ETOPS authority in a certificate holder’s application willnecessarily have to be assessed differently for ETOPS beyond 180 minutes.(1) Two-Engine Airplanes up to 180-Minute ETOPS and 207-Minute ETOPSAuthority in the North Pacific Area of Operations. The ETOPS area of operation is the areabounded by distance circles representing the approved one-engine inoperative cruise speed understandard conditions in still air chosen by the applicant. The actual flight plan must comply withthe fuel supply requirements in § 121.646(b) and must therefore account for wind. However, theflight planning limitations of § 121.633(a) for airplane systems do not require the operator toaccount for wind in such calculations for flight planning and for determining the ETOPS area ofoperations in these cases. This allows the applicant to choose an operating authority in his or herapplication that is based on the “ETOPS area of operation” determination. In other words, thedistance from alternates in a certificate holder’s route planning exercise will be the same valueused to determine the type design criteria for the airplane-engine combination used in theoperation, and the ETOPS approval necessary to fly the route under all flight planningconditions.(2) ETOPS Beyond 180 Minutes (Two-Engine Airplanes and All Passenger-Carrying Airplanes With More Than 2 Engines). As required by § 121.633(b), for ETOPSbeyond 180 minutes for all airplanes, the ETOPS operation must account for the effects of windand temperature on the calculated distances. Consequently the planning for an ETOPS flightbeyond 180 minutes is more complex.(a) The certificate holder should first conduct a route planning exercise for eachplanned city pairing to determine the diversion authority needed in still air conditions. If theroute or segments of the route exceed 180 minutes based on one engine inoperative speed andstill air, then a secondary planning exercise (that may be required seasonally) should beconducted that factors in expected winds and temperatures on that route. The distance betweenadequate alternate airports on the route is converted into time (minutes) computed for all enginecruise speed, as well as engine inoperative speed. The number of minutes cannot exceed thetime-limited system certified capability (cargo fire suppression and the other most limitingsystem)that is identified in the Configuration Maintenance Procedures (CMP) or Aircraft FlightManual (AFM) (or any other FAA-approved manufacturer’s document) less the 15-minute pad.The operator needs to determine how much system capability is required for the planned routeand equip its airplane to have sufficient margins. Finally, for the actual flight, the operator’sflight planning must be within the airplane systems capability for the selected ETOPS alternateairports on the planned route based on diversion times that are calculated using known orforecast winds and temperature conditions.(b) As a minimum, the certificate holder must ensure that the time-limited systemsrequirements of § 121.633(b) are met at the equal-time points between ETOPS alternatesdetermined by the most limiting en route fuel supply requirements of § 121.646(b), commonlyreferred to as the ETOPS critical fuel scenario. Certificate holders flying three- and four engineairplanes, prior to the established installation time and certification time requirements of theregulation for these systems and their airplanes, are exempt from these flight planninglimitations.Par 205 Page 9