Please could someone tell me about ETOPs.
HISTORY
The “60 Minute Rule”
The FAA created the requirements found in FAR section 121.161 as early as 1936. The initial regulation applied to all aircraft regardless of how many engines they had. The regulation restricted operations to an en-route area that was within 100 miles of an adequate airport. In 1936, 100 miles equated to about 60 minutes flying time if one engine was inoperative.
The initial FAA “60 minute rule” was established in 1953. The rule was written based on the reliability of the piston engines being used during the late 1940’s and early 1950’s. It restricted twin engine aircraft to areas of operations that were 60 minutes from an adequate airport at the one engine inoperative cruise speed, in still air, at standard atmospheric conditions. The Rule was flexible in that it permitted operations beyond 60 minutes if special approval was obtained from the FAA. The approval took into consideration the character of the terrain, the kind of operation, and the performance of the aircraft.
The purpose of the rule was to restrict the flying time to the alternate. This, in turn, would reduce the risk to an acceptable level. In other words, the rule addressed the lower end of reliability in piston power plants to ensure that if an engine failed at any point along the route, the aircraft could proceed to and land at the alternate before losing the remaining engine.
High Bypass Engines and the Wide Body Twin Aircraft
The early 1980’s showed great advances in the aircraft operational environment, design reliability and integrity. These advances were made possible by the highly satisfactory JT8D experience and the knowledge gained from the operational introduction of the Pratt & Whitney JT9D, the General Electric CF6, and the Rolls Royce RB211 large high bypass engines.
Wide body jets started service in 1974 and operators took advantage of the ICAO 90 minute rule where, by the old rules, they were forced to use three and four engine aircraft. It was found that jet engine power and size did not appear to have any noticeable impact on failure rate. The failure rates of some of the large high bypass engines were almost as good as the JT8D and nearly ten times better than piston engines.
Interest in the “120 Minute Rule”
Operations in the North Atlantic Track System (NATS) generated an interest in 120 minutes ETOPS. NATS operations were, by their nature, extremely competitive and the concept of using wide body twin engine aircraft was a very attractive proposition. This was especially true in light of the fact that the old “60 minute rule” required indirect routings (random routes) and the use of en-route alternates that had limited airport services and facilities and were subject to frequent weather limitation
Operations under a “120 Minute Rule” would allow for the use of minimum cost routings (Organized Track System) and enable the use of alternates that were properly equipped.
The aviation industry realized that all twinjets could now be designed with performance and safety improvements that permitted them to safely conduct operations that had been previously restricted to three and four engine aircraft. The new generation of aircraft with their efficiency, safety, range and payload capabilities made the old “60 Minute Rule” inappropriate.
Early in 1980, ICAO formed a study group to examine the feasibility of extended range operations with the new generation twinjets. They also set out to define the criteria that should be met to ensure that these operations were conducted with the highest possible level of safety. Around the same time the FAA began initial work on what would become Advisory Circular (AC) 120-42. This circular presented the U.S. Criteria for ETOPS. The ICAO study group recommended the establishment of a new ICAO rule to recognize the capabilities of the new generation aircraft and the limitations of the older aircraft.
120 Minute ETOPS Operations
In 1985, the FAA issued AC 120-42 which set the criteria for the approval of a deviation in accordance with FAR 121.161 to increase the ETOPS area of operations to 120 minutes at the single engine cruise speed under standard conditions in still air. The AC also permitted areas of operation as great as 138 minutes if additional criteria were met. Several other aviation authorities issued ETOPS criteria including CAA UK, DGAC France, DOT Canada, and DOT Australia.
180 Minute ETOPS Operations
The experience with 120 minutes ETOPS led the governing authorities and industry to consider the feasibility of 180 minutes ETOPS. Operators were most interested in the “180 Minute Rule” because it meant that almost any route in the world could be economically serviced by twinjets.
On 30 December 1988 the FAA issued AC 120-42A which provided criteria for 75, 120 and 180 minute ETOPS operations. On 18 January 1989, the FAA approved the first 180 Minute ETOPS operations.
240 Minute ETOPS Operations
Airline manufactures and a number of airlines are presently requesting the governing authorities to consider the feasibility of 240 minutes ETOPS. This would allow ETOPS operations across the Pacific Ocean.
What is an adequate/suitable aerodrome?
Bally Heck already answered that…
What things are considered for an airline to be certified for 180 mins ETOPs?
These actually apply to all ETOPS certification; the maximum IFSD rate varies with the level of approval.
Type Design Approval
To achieve type design approval, the essential airframe systems and propulsion system should be designed to fail safe criteria and through service experience it should achieve a defined level of reliability. This should include the availability of electrical power for essential flight instruments, warning systems, avionics, communication, navigation, oxygen requirements, and cargo fire protection system capability.
Operational Approval
Continuing airworthiness maintenance of aircraft, flight dispatch procedures, Minimum Equipment List, Communication and Navigation facilities, fuel supply, alternate airports operating minima and flight crew training are required to obtain operational approval.
What are the various ETOPs categories?
90mins, 120 mins, 138 mins, 180 mins, 240 mins.
One would never guess that I work for an airline that received ETOPS 120 minutes approval two weeks ago…..
Mutt.