PERCENT OF SIMULTANEOUS HOURLY OBSERVATIONS OF BELOW ETOPS MINIMUM CEILING AND/OR VISIBILITY
SAPPORO, KUSHIRO, & HAKODATE (RJCK & RJCH CLOSED AT NIGHT)
TIME
Simultaneous Weather Reliability Statistics for the North Pacific – Northern Japan
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NORTHERN JAPAN AIRPORTS
MONTHLY AVERAGE WX BELOW ETOPS MINIMA (RJCK & RJCH CLOSED AT NIGHT)
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
1 2 3 4 5 6 7 8 9 10 11 12
MONTH MONTHLY AVERAGE PERCENT OF OPEN HOURS BELOW ETOPS MINIMA
RJCC RJCH RJCK
Figure 4.10 North Pacific – Individual Northern Japan Alternate Weather
NORTHERN JAPAN AIRPORTS
SIMULTANEOUS PERCENT BELOW ETOPS MINIMA (WITH KUSHIRO & HAKODATE CLOSED AT NIGHT) BASED ON RJCC DATA ONLY FROM 1200Z-2200Z
2.0%
4.0%
6.0%
8.0%
10.0%
12.0%
14.0%
16.0%
18.0%
20.0%
MONTHLY AVERAGE PERCENT OF OPEN HOURS BELOW ETOPS MINIMA
RJCC / RJCK / RJCH
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4.2.2.6 Passenger Recovery Planning Data
The Passenger Recovery information indicated in Table 4A is another category of data that is not specifically required for an airport to qualify as “Adequate”, but it will be required to support an operator’s Beyond-180-Minute ETOPS application. A basic requirement of a provider of public transportation is to ensure that the traveling public using their services will be protected from undue hazards and danger. For FAA Part 121 certified operators, this intent has long been stated in 121.97, which is repeated in part here for reference.
“…(b) Each certificate holder conducting domestic or flag operations must show that it has an approved system for obtaining, maintaining, and distributing to appropriate personnel current aeronautical data for each airport it uses to ensure a safe operation at that airport. The aeronautical data must include the following:
(1) Airports
(i) Facilities
(ii) Public Protection (iii) …Etc.”
With the adoption of the 2007 ETOPS rules, the public protection requirement of paragraph (ii) has been expanded for ETOPS Beyond-180-Minutes to include the listing of facilities located at each airport, or in the immediate metropolitan area, sufficient to protect the passengers and crew from the elements and to see to their welfare. This requirement is interpreted in the guidance of AC 120-42B to encompass the time from landing until satisfactory recovery of passengers and crew based on the certificate holder’s passenger recovery plan as required by 121.135. It is generally accepted that any plan that is designed to fully recover the passengers within 48 hours may be viewed as meeting the overall requirement to provide for the care and safety of the passengers and crewmembers. The greatest concern relative to passenger recovery plans is when diversions occur to an airport that is geographically located within an area not normally served by the certificate holder and, more specifically, when the diversion occurs to an en route alternate airport located in a harsh operating environment. FAR 121.135 requires that for ETOPS-Beyond-180-Minutes operations by flag and supplemental passenger carriers, airport specific Passenger Recovery Plans must be developed for all ETOPS Alternate airports that an operator might use in case of an inflight emergency that requires landing at the nearest airport. A similar requirement exists for each diversion airport used in North and South Polar Operations by all passenger carriers. It should be noted that 207-Minute ETOPS is considered an extension of an operator’s 180-Minute Approval and is therefore exempted from the specific Passenger Recovery Plan requirement.
4.2.3 One-Engine-Inoperative Speed Effects on Area of Operation
When selecting a one-engine-inoperative speed for ETOPS planning, the operator will need to consider the various ways in which the selected speed may impact their operation. In addition to being used to calculate the zero wind ETOPS Area of Operation; FAR 121.646 requires it to be
SECTION 4 – ETOPS ROUTE PLANNING – THE APPLICATION PHASE
with the other most time-limited-system requirements of 121.633. It may also be used to calculate terrain clearance over mountains or other high terrain unless, as is noted in paragraph 403 of AC 120-42B, it is determined that using a terrain clearance procedure at a different speed such as Max L/D Speed does not increase the ETOPS Diversion Fuel required or exceed the time-limited-systems requirements. Lastly, it must be within the airplane’s operational speed capability, (Max L/D Speed to Vmo/Mmo) and be listed in the operator’s Operations Specification.
With all these sometimes conflicting requirements it can be a bit challenging for an operator to select the best speed for their particular operation. This section will focus on the issues that the operator should consider in selecting their one-engine-inoperative speed.
4.2.3.1 One-Engine-Inoperative Driftdown
An airplane in a normal all-engine cruise condition near optimum altitude will not be able to maintain the cruise altitude and speed following the loss of thrust on one engine, even with the application of Maximum Continuous Thrust on the remaining engine(s). As a result, the airplane will immediately begin to descend and/or slow down, depending on the actions taken by the flight crew. At the Max Continuous Thrust setting, the thrust of the operating engine(s) will increase as the airplane descends into more dense air, and when it once again equals the total airplane drag, the airplane will be able to maintain altitude. The maneuver that the airplane is executing is called an engine-out driftdown, and the flight path is referred to as an engine-out driftdown profile. The horizontal distance that the airplane traverses during this maneuver forms the basis of the ETOPS Area of Operation, as is referenced in paragraph 205.d of AC 120-42B.
In the simplest form the ETOPS Area of Operation can be thought of as:
Distance = (Speed) x (Time),
where the speed is the operator-selected one-engine-inoperative cruise speed and the time is the maximum diversion time being applied for by the operator. The speed would be in Knots True Airspeed, and the time would be in hours to produce a distance in Nautical Miles. However, it should be remembered that the flight crew will be conducting the engine-out driftdown and diversion using an airspeed instrument that displays Indicated Mach number and airspeed, not true airspeed. This constant indicated airspeed descent produces a higher average true airspeed during the initial portion of the diversion until the final single engine cruise altitude is reached.
As a result, the distance covered in first 60 minutes of the diversion is greater than in the second and subsequent hours. Figure 4.12 shows this effect during a typical engine-out driftdown maneuver conducted at M=0.84/320KIAS. The initial cruise conditions are FL350 and M=0.84 with an indicated airspeed of 287 KIAS and a true airspeed of 484 KTAS. In order to maintain the desired Mach 0.84 speed, the pilot must initiate an immediate descent following the engine failure. During the first few thousand feet of the driftdown, the airplane Mach number is
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0 60 120 180
150 400 500
Average True Airspeed for first hour ~ 431 KTAS
Average True Airspeed for second hour ~ 412 KTAS Average True Airspeed for first two hours ~ 421 KTAS
Average True Airspeed for third hour ~ 411 KTAS Average True Airspeed for first three hours ~ 417 KTAS
TRUE AIRSPEED
0 DISTANCE FROM ENGINE FAILURE ~ NM431 842 1250 min
INITIAL CONDITIONS M=0.84 FL350 GW = 280000 KG
DRIFTDOWN @ M=0.84 / 320 KIAS
ENGINE FAILURE
Figure 4.12 Engine-Out Driftdown Profile
As a result, the distance flown during any given time interval can no longer be calculated by simply multiplying the speed and time. During the early days of ETOPS, some national regulatory authorities specified that the final true airspeed at level-off would be used to calculate the ETOPS Area of Operation, which resulted in a uniform progression of circle sizes such as 400-800-1200 nm for 60, 120, & 180 minutes. However, this was determined to be too conservative and most modern regulations now are harmonized on the use of the distances determined from a driftdown profile, as discussed above.
4.2.3.2 Boeing ETOPS Area of Operation & Diversion Distance Table
Operators typically can calculate a driftdown profile using manufacturer supplied software such as Boeing’s INFLT and/or the Boeing Performance Engineers Tool (PET). However, Boeing has simplified this process by providing operators with a table in the Flight Planning and Performance Manual and/or performance software tools which allows the operator to determine the distance flown in a specific length of time as a function of indicated Mach number and
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airspeed. An example of this data is shown in Table 4H. Since the engine-out level-off altitude is directly affected by the airplane weight, the data in Table 4H is also presented as a function of the weight at the diversion point.