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PBNنگاهی دوباره به تعریف

• Performance-based navigation (PBN).– Area navigation based on performance

requirements for aircraft operating along an ATS route, on an instrument approach procedure or in a designated airspace.• Note.— Performance requirements are expressed in navigation

specifications (RNAV specification, RNP specification) in terms of accuracy, integrity, continuity, availability and functionality needed for the proposed operation in the context of a particular airspace concept.

GNSS augmentation• Ground Based Augmentation System (GBAS), Satellite Based

Augmentation System (SBAS), • Aircraft Based Augmentation Systems (ABAS)• Ground Based Regional Augmentation System (GRAS)

to meet navigation requirements

APV

• Two types of approach and landing operations with vertical guidance (APV), APV-I and APV-II, use vertical guidance relative to a glide path, but the facility or navigation system may not satisfy all of the requirements associated with precision approach.

APV

• Approach with Vertical guidance (APV)• Will enhance safety and efficiency by

providing guided and stabilized vertical guidance on approach procedures where currently no guidance exists

APV• GBAS, SBAS and GRAS are planned to provide (APV) performance levels

that are similar to that of CAT I ILS (200 – 250 ft decision height). • Currently GBAS is the only GNSS system that potentially will provide CAT II

and CAT III performance levels. • ABAS currently enable minima’s in the region of 350 feet (above ground).

However, it is not unreasonable, based on current operational trials, technical analysis and the planned future operation of multiple constellations, to expect that this capability may be enhanced in the future to enable ABAS performance levels near to that of CAT I ILS.

APV- I & APV-II performanceAPV-II APV-I Performance Requirement

16 m 220 m Horizontal Accuracy (95%)

8 m 20 m Vertical Accuracy (95%)

/Approach

/ Approach Integrity

/15 s /15 s Continuity

40 m 0.3 nmi Horizontal Alert Limit (HAL)

20 m 50 m Vertical Alert Limit (VAL)

99%- 99.999% 99%- 99.999% Availability

6 sec 10 sec Time To Alert (TTA)

Approaches with lateral and vertical guidance

• APV can be provided in two ways. Either Barometric Vertical Navigation (Baro VNAV) where the FMS generates a continuous descent path using barometric altimeter information or geometric vertical guidance provided by an augmented Satellite based signal.

• Modern air carrier airplanes have FMS vertical navigation (VNAV) modes. When this capability is combined with FMS lateral navigation (LNAV) mode, a three-dimensional approach path to the runway can be defined and flown.

APV/Baro VNAV

• APV/Baro VNAV (using ABAS) is the most cost effective and quickest way of implementing APV as most of today’s civil transport aircraft have navigation equipment on board that is able to support this type of approach. APV/Baro VNAV generally enables approach minima’s lower than those for NPAs.

RAIM• ABAS are self contained on board the aircraft and rely upon avionics

processing techniques or avionics integration. • Receiver Autonomous Integrity Monitoring (RAIM) provides integrity

monitoring of GPS for aviation applications. • In order for a GPS receiver to perform RAIM a minimum of 5 visible

satellites with satisfactory geometry must be visible to it. • The RAIM function performs consistency checks between position

solutions obtained with various subsets of the visible satellites. • The receiver provides an alert to the pilot if the consistency checks fail.

Because of geometry and planned maintenance RAIM is not always available. In this situation pre warning is given to users of ‘RAIM outage’.

Aircraft Autonomous Integrity Monitoring

• With Aircraft Autonomous Integrity Monitoring (AAIM), the integrity of the GPS solution is validated using other on board information sources, such as the Inertial Platform, in addition to those used in RAIM.– AAIM/ Baro using the barometric altimeter information;– AAIM/ MS using Multi-Sensor information based on

ground navaids signals (VORs, DMEs, ILS/LOCs);– AAIM/ INS using the inertial sensor information.

WAAS (as an example)• The Wide Area Augmentation System (WAAS) is an air

navigation aid developed by the Federal Aviation Administration to augment the Global Positioning System (GPS),

• with the goal of improving its accuracy, integrity, and availability.

• Essentially, WAAS is intended to enable aircraft to rely on GPS for all phases of flight, including precision approaches to any airport within its coverage area.

برخی تعاریف• Channel of standard accuracy (CSA). The specified

level of positioning, velocity and timing accuracy that is available to any GLONASS user on a continuous, worldwide basis.

• Standard positioning service (SPS). The specified level of positioning, velocity and timing accuracy that is available to any global positioning system (GPS) user on a continuous, worldwide basis.

WAAS Accuracy• The WAAS specification requires it to provide a position accuracy of 7.6

metres (25 ft) or better (for both lateral and vertical measurements), at least 95% of the time

• Actual performance measurements of the system at specific locations have shown it typically provides better than 1.0 metre (3 ft 3 in) laterally and 1.5 meteres (4 ft 11 in) vertically throughout most of the United States and large parts of Canada and Alaska

• With these results, WAAS is capable of achieving the required Category I precision approach accuracy of 16 metres (52 ft) laterally and 4.0 metres (13.1 ft) vertically.

WAAS Integrity• Integrity of a navigation system includes the ability to provide timely

warnings when its signal is providing misleading data that could potentially create hazards.

• The WAAS specification requires the system detect errors in the GPS or WAAS network and notify users within 6.2 seconds. Certifying that WAAS is safe for instrument flight rules (IFR) requires proving there is only an extremely small probability that an error exceeding the requirements for accuracy will go undetected.

• Specifically, the probability is stated as 1×10−7, and is equivalent to no more than 3 seconds of bad data per year. This provides integrity information equivalent to or better than Receiver Autonomous Integrity Monitoring (RAIM).

WAAS Availability

• Availability is the probability that a navigation system meets the accuracy and integrity requirements. Before the advent of WAAS, GPS could be unavailable for up to a total time of four days per year

• The WAAS specification mandates availability as 99.999% (five nines) throughout the service area, equivalent to a downtime of just over 5 minutes per year.

در خصوص سامانه های سنتیسامانه های سنتی نیز دارای خطا هستند.•خطای سامانه های سنتی عموما ثابت است و •

در زمان تغییر نمی کند.سامانه های سنتی دارای سیستم مانیتورینگ •

هستند که در صورتی که خطا از حد مجاز برای کاربرد مورد نظر کمتر شود سامانه را از

سرویس خارج می کنند. در صورتی که برای VORخطای سامانه سنتی •

درج می شود.AIPناوبری نامناسب باشد در

پایان قسمت نهم

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