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Mar 12, 2019 in Analysis

What is Extended Diversion Time Operations

EDTO is corresponding to ETOPS, the formerly used conception of extended range operations. It essentially relates to any flight by a turbine-engine aircraft, and if one engine fails, the total flight time taken from any point of the marked route to the nearest aerodrome is higher than threshold time for that particular aircraft’s type and weight. This timing could either 90 or 180minutes. In most cases, threshold time is typically considered to be the safe limit in relation to radial distance from the landing field. Therefore, with absence of these respective safety factors, this distance ought not to be exceeded, thus providing an aircraft with engine failure ample time to get to aerodrome. 


Extended Diversion Time Operations are policy guidelines being an improved version of Extended-range Twin-engine operations (ETOPS) by International Civil Aviation Organization (ICAO). The new version was introduced in 2007 to cover some shortcomings of ETOPS. At the time of their conception, ETOPS guidelines had been in use for about 20 year and were formulated in the year 1985 being more concerned with extended-range operations that mainly related to two-engine airplanes. The guidelines provided a limited distance that two engine airplanes needed to fly away from a diversion airfield. These guidelines were meant to reduce the risk for airplane by offering it ample time to reach a nearest airfield in case of emergency.  

In those early days, it was considered as bigger risk for the two engine aircrafts to fly far from diversion airfields, and thus, they were required to fly within a maximum of sixty minutes distance from an airport. Since air technology is being improved and becomes more reliable, the prospects of airplanes covering longer distances and operations in remote areas have pushed Federal Aviation Administration (FAA) and International Civil Aviation Organization to accept the revision of ETOPS guidance. One of the major reasons for this review was to broaden the guidelines to cover airplanes that have more than two engines. With the review, the name of the guidelines was changed from Extended-range Twin-engine Operations (ETOPS) which mainly covered two engine aircrafts to a more general term Extended Diversion Time Operations (ETDO). 

Further, the amended EDTO guidelines will lead to more direct operations with non-stop flights above oceanic or isolated land areas. Furthermore, they will not be required to fly through intermediate points, which forces them to have more landings and take-offs. The changes were introduced in the year 2007. Today the diversion time has moved to higher time threshold such as flying 180 minutes from a suitable aerodrome.

Thesis statement

Extended Diversion Time Operations (EDTO) guidelines have positively affected the growth of aviation industry as compared to their previous form recognized as Extended-range Twin –engine Operations (ETOPS) guidelines that just covered to engine aircrafts. 

Differences between EDTO and ETOPS

The most common differences between ETOPS and EDTO include alternate aerodromes for EDTO unlike for the ETOPS. While ETOPS advocated for a 60 minute threshold diversion time, EDTO has pushed the threshold to 90 minutes, 180 minutes and even 240 minutes. Further, the range circles in ETDO are higher than those within ETOPS covering extra number of nautical miles. Unlike ETOPS requirements, ETDO do not necessarily require the window of suitability. Finally, ETDO is applied to all aircrafts as opposed to ETOPS that is only applied to twin engine airplanes. However, the two guidelines have a similar weather holding requirements.

Importance of Extended Diversion Time Operations

The significant changes provided by EDTO made it easier and cheaper for airplanes to operate considering the improved technologies. Although there are prescriptive requirements, many areas are currently viewed on the basis of performance-based alternatives that exist to help operators save fuel. Moreover, the substitution of ETOPS with ETDO has brought inclusivity in the industry since the new guidelines cover all aircrafts as opposed to twin engine airplanes only. 

The new rules will create a possibility for aero-planes to engage in more direct and non-stop flights above oceanic areas or uninhabited lands. This will greatly boost the industry since it will reduce the time taken for some journeys, thus lowering the cost of fuel consumed. This is primarily because the approved diversionary time limits have been raised in three additional approval stages. The additional approval stages will allow operators of technologically advanced planes to attain full operational abilities as well as the best airplane range after acquiring the corresponding safety standards. 

Further, by allowing direct flights to extra destinations that have more frequencies, EDTO ensures existence of fewer connections and minimal delays which will be advantageous to passengers since it saves time and is convenient for them. Moreover, the passengers on long routes, where their number may not be economically viable to use bigger aircraft, may get the chance to use an efficient twin engine airplane, thus lowering their fares.

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As used by ETOPS guidelines longer route

As used by EDTO shorter routes

Additionally, EDTO rules are meant to assist in enforcing safety standards. The requirement to have the approval by CAA is mandatory as opposed to voluntary which ensures proper mechanisms to enforcing the laws. There is an intention to ensure that with the diversion time having been raised, the operators of airplanes ought to be properly following the safety guidelines provided. Moreover, EDTO rules on a three or four engine aircraft provide consistency among operators of different multi-engine aircraft types that includes both the twin-engine and those with more than two engine aircrafts in the same fleet.

EDTO Specific Requirements

The fundamental program for the maintenance of an aircraft that is due for consideration of Extended Diversion Time operations is the continuation of airworthiness program approved for that particular operator, the model and the air-frame engine combination. It is important that the program is reviewed to give enough reasons for developing the Extended Diversion Time Operations requirements. The process includes procedures for maintenance to prevent common human errors that can be avoided through a verification process or by conducting operational testing before the EDTO. 

For a twin engine aircraft, another person should perform the maintenance of different element that is identical but from separated maintenance vital systems whether during the same habitual or non-habitual visit. In regard to aircrafts that have more than two engines, an individual is prohibited to provide maintenance of a similar element that is identical but with different maintenance significant systems on either two engines of a three engine plane or beyond one engine on every side in a four engine airplane. Where the situation is unavoidable, sufficient ground tests should be performed, inspection procedures involved and verification flight procedures commenced. Where EDTO related tasks have been detected, they must be incorporated through the routine work forms belonging to the operator. 

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Further, such EDTO procedures as inclusion of a central maintenance control should have a clear definition in the operator’s program. Service checks include verification of the good condition and status of the aircraft while ensuring that certain important items are suitable to support the extended diversion time operations program. The checks ought to be performed and signed by a well-trained maintenance individual before an EDTO flight. The aero plane’s log book should be thoroughly reviewed and properly documented as suitable to ensure that appropriate MEL procedures have been adhered to as well as allow proper maintenance checks and performance of system verification procedures. 

Every operator is expected to develop a manual that will be used by the individuals participating in the extended diversion time operations. It is necessary to include maintenance program among other programs in the manual. All of the EDTO requirements, such as supportive program procedures as well as duties and responsibilities, ought to be identified and further subjected to revision controls. The information could be included in the manual if necessary. Moreover, there should be an outlined procedure of the fuel consumption. The program should depict the aircraft manufacturer’s recommendations as well as reveal sensitivity in the fuel consumption trends. It should consider the amount of fuel that has been added in every station in relation to the existing average consumption. That is, it ought to show continuity with the inclusion of the fuel added at departure station. In cases where fuel analysis is important for the type of aircraft model, the procedure needs to be included in the program. 

Moreover, in case the auxiliary power-unit is necessary for the EDTO, it should be also included in the fuel consumption program. In addition, there should be an engine condition monitoring program. The program should give description of the parameters that must be checked, data collection method, and a corrective action process. The program should echo the industry’s practices as well as manufacturer’s directives. This type of monitoring will help detect early stages of deterioration, thus allowing collective actions before the already secure operations are affected. 

Moreover, the program ought to ensure maintenance of engine-limit margins so that one prolonged engine failure diversion is conducted devoid of surpassing the standard engine limits. Further, the engine margins that are preserved though the program need to consider the effects of extra engine loading requirements that may be necessary throughout the single engine inoperative flight period connected to a diversion.

EDTO has a number of requirements that the operators are required to meet to ensure efficient operations. First, there are fuel carriage requirements. These are important in ensuring an improvement in efficiency as well as reducing emissions in a safe manner. In its implementation using the ICAO current approach, aircrafts fuel must be kept safe where the caps locking the fuel tanks are ware tight to avoid entry of foreign materials that may contaminate the fuel, thus causing safety risks. The requirement is that the fuel should always remain clean. Contaminated fuel is a threat to the plane and may lead to a poor combustion, thus becoming a greater risk that may lower the safety standards of the plane. 

Further, the amount of fuel that an aircraft is able to carry is of utmost importance. To extend diversion time, one requirement is that the aircraft must be in a position to carry enough fuel to help it get to the airfields that are far away. For every destination, the fuel factor comes to question to avoid the danger of having the fuel get drained in the midair, thus causing an accident. Secondly, the regulations ensure that operators performing EDTO control safety systems that monitor reliability of every participating airplane as well as other systems. This enhances the safety of the extended range operations through additional requirements that include demonstration of proven capabilities to operate by an operator at shorter extended-range before getting an approval for longer range capabilities. The main purpose is to ensure that the operator develops the best levels of experience in order to guarantee the safety of the aircraft. 

By requiring that operators first get experienced with the shorter extended range, the regulations also ensure that they gain enough confidence, and thus, will be ready to operate in even longer extended range. The advantage of the longer extended range is that it will save more time as well as fuel costs. Another EDTO requirement concerns the design of an aircraft. EDTO requires that an airplane must have minimum three inbuilt reliable and independent generators. Each of these generators should have the ability to supply all the required services that would ensure continuation of a secure flight and safe landing under any unfavorable operating conditions. The need for these generators is to ensure that the failure of one generator does not deter the normal operations of the airplane during the flight. 

Again, at times a fourth generator may be required to power a cross feed valve as well as power fuel pump in every fuel tank. With a number of generators, the aircraft is fairly equipped to undertake longer journeys providing a good chance to increase its extended diversion time operations without the fears of any potential danger terminating core activities of the plane. The high number of generators is important for backup purposes in case there is a failure of one of them. 

Further, EDTO regulations necessitates the need for cargo-fire protection system, which will cover the longest diversion time that has been approved as well as a fifteen minutes allowance time for holding and landing. For example, For 120 minutes EDTO, 135 minutes minimum safety time is needed, while 180 minutes EDTO 195 minimum safety time would be required. Cargo holding protection time is established by the flight tests, and the time limit is usually identified by FCOM, AFM and Extended Diversion Time Operations CMP Document. In most cases, the time capabilities of cargo fire suppression system are mainly 260 minutes. For every fire extinguisher high rate discharge bottle there need to be a provision of initial fifteen minutes suppression time. 

Furthermore, fuel cross feed into an operative engine in single engine operations for a twin engine aircraft must be protected against any single malfunction that may arise. Engine operations should be well evaluated due to turbulence effects as well as the negative “G”. This is to help check whether the fuel boosting pumps are powered, for example, by checking limitations in electrical configuration emergencies. Moreover, it will show whether losing all fuel boosting pumps may not be depicted as extremely improbable. In regard to the weather safety requirements, most of the ETOPS guidelines have been maintained in EDTO guidelines. Some of these guidelines include those calling on pilots to avoid continuing a flight towards an airport it has been dispatched if in their own opinion the flight may not be completed. 

Regarding environmental matters, the discretion to rule is left with the pilot. These rules also require that the instruments and equipment that will assist the pilot in making the right decision needs to be always at their disposal. Moreover, before taking any flight the EDTO regulations require that the pilot or the captain check all the documents of registration and other authorizations allowing the aircraft to be flown. In case some of these documents are missing, the guidelines require that a flight is not taken. Similarly, the ETOPS, EDTO requirements indicate that no person is allowed to be authorized to dispatch an aircraft for an EDTO flight if they are not certain of enough EDTO Alternate Airports that are clearly listed on the dispatch such that they remain inside the authorized EDTO maximum diversion time. 

During the selection of EDTO Alternate Airports, the certificate holder should consider all satisfying airports that lie within the approved EDTO diversion time in relation to flights that meet those standards. Further, the guidelines prohibit anybody from listing any airport as an EDTO alternate airport in a flight release except in cases where the airport may be put to use. Suitable weather reports will indicate that weather conditions are above EDTO Alternate Airport lows that are specified in certificate holder’s specific operations. In such a case, safe landing would be appropriate. When the flight is en route, the weather conditions at every EDTO alternate airport ought to meet all the guidelines under the number 121.631.

To meet EDTO guidelines, the airport should acquire the following characteristics which include availability, be compatible with performance requirements to handle an expected landing weight, be fixed with ground operational services such as lighting and weather reporting, ATS and communication system. Further, the airport must have one or more let-down navigation aid which may be VOR, Radar, ILS or NDB. This is purely to ensure that the communication with a landing plane that could be in danger is fast and uninterrupted. Moreover, they will ensure recognition of the aircraft as it nears the airport. 


In conclusion, meeting EDTO guidelines help improve the entire aviation industry. This is clearly evidence by the EDTO guidelines to cover all airplanes as well as tightening the safety measures. For example, EDTO guidelines require an airport recognized by it to be compatible with performance requirements, available, and be enhanced with lighting and weather reporting gadgets. Further, unlike ETOPS, EDTO have created for an opportunity to have Extended diversion time raised thus reducing cost of fuel as well as the time required to fly to different destinations.

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