1. International Training: Area Navigation Fundamentals
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2. Agenda 1. Area Navigation Airspace
2. Navigation Performance Requirements
3. ANP and FTE: Managing Error
4. Waypoints & Path Terminators
5. Approaches

3. Objectives A basic understanding of: Area navigation airspace concepts
The relationship between RNAV and RNP
How RNAV systems work
Managing tracking error
You will be able to identify the requirements for operating in the various airspace along with what to do if you need to perform contingency procedures.

4. Area Navigation Destination Destination Origin Origin
Area navigation offers a number of advantages over conventional, ground-based navigation systems, including greater safety and efficiency. Like a lot of things, area navigation has evolved from it’s origin of direct waypoint to waypoint to meet ever changing needs.

5. Area Navigation Applications
RNAV Applications
Applications, such as RVSM and B-RNAV were formed to ensure operators meet the requirements of the airspace.
The evolution came through various RNAV applications. Airspace and procedures defined requirements for different navigation equipment and performance capabilities.

6. Area Navigation Evolution
Navigation performance standards enhanced RNAV capability from the original direct waypoint to waypoint. RNAV applications utilize RNAV capabilities requiring varying degrees of required performance capabilities. These applications are currently being standardized as Performance Based Navigation (PBN).

7. RVSM Airspace
RVSM airspace is any airspace or route where aircraft are separated by 1,000 feet vertically, between FL 290 and FL 410, inclusive. There are many applications worldwide, be careful as there may be slight differences between applications. Let’s briefly look at RVSM in the United States.

8. Domestic RVSM
In addition to area navigation, RVSM was introduced in 2005 domestically. RVSM allows more aircraft at the most fuel efficient altitudes. One difference between domestic RVSM and oceanic RVSM is that unlike oceanic RVSM you need to request a strategic lateral offset .

9. D RVSM East West Rules
Flight levels 310, 350 and 390, which were once westbound under conventional separation are now eastbound in domestic RVSM airspace.

10. MNPS Airspace
MNPS airspace will remain the same under the transition to PBN.

11. MNPS/RVSM Equipment
MNPS/RVSM airspace will remain the same, although you must do the same thing; always meet the equipment and performance requirements. For MNPS airspace two or more LRN systems are required. One is allowed if using special routing. No entry into MNPS if all LRN systems fail.

12. Domestic RVSM Equipment
Here are the equipment requirements for domestic RVSM. Now let’s look the rest of the airspace under performance based navigation.

13. PBN Airspace RNAV 10 It’s all area navigation these days! RNAV 5…
It’s all area navigation these days!
RNP 4
RNP 1
RNP APPR …
Airspace using area navigation methods is identified by two names; RNAV airspace and RNP airspace. There are two parts to the designator; the type of area navigation and a number.

14. RNAV vs. RNP RNAV requires accuracy only
RNP requires accuracy plus alerting
RNP airspace or procedures usually have accuracy requirement of less than one
RNP with accuracy requirements one or above are generally used in non-radar environments
The type of area navigation is either RNAV or RNP. RNP airspace is RNAV airspace with one additional requirement; set up the RNP value in the FMC to alert you when the airplane’s navigation system doesn’t meet the accuracy requirements. Also, sometimes there are some extra procedural requirements that require authorization and training for some special use RNP applications.

15. Airspace Performance RNAV 5 RNP 1
“The Number” is a statement of the navigation performance accuracy necessary for operation within a defined airspace
Stated as a number in nautical miles
Specifies how “tight” the avionics must contain navigation position error
Specifies how “tight” you must fly the route
During operation in both RNAV and RNP airspace we need to monitor the status of the navigation equipment as well as our actual track to ensure that the airplane is actually flying within the accuracy requirement (number).
The number tells you both the equipment requirements as well as the performance requirements for a particular airspace. You have to have equipment that meets the accuracy level (number) 95% of the time And you must remain within that number of nautical miles 100% of the time.

16. Equipment Requirement
Requirement for approval
Equipment necessary to meet the requirement must be operational to enter and continue in the airspace
95%
For approval and entry into the various airspace, the equipment must be capable of maintaining the navigation position accuracy to within the specified limit 95% of the time. For example the position error must be less than 1nm 95% of the time for both RNAV 1 and RNP 1.

17. N767A FMC’s Watch Carefully FMC & Sensor Condition Flying Accuracy
Since we have the equipment that meets the requirements, we don’t need to worry about the 95% of the time details. We need to watch the condition of the FMC’s , and required navaids (or sensors) to make sure our equipment continues to meet the requirements. Also we have to do pilot job number one and make sure we are accurately flying the track.

18. Operational Requirements
Feed Me
FMC
As mentioned earlier, the airplane needs the proper updating as well as adequate system health to achieve acceptable actual navigation performance (ANP). Let’s take a closer look.

19. FMC Position Update Priority
Sensors Priority
one LOC and GPS (tuned for approach)
one LOC and collocated DME (tuned for approach)
one LOC and VOR with a collocated DME (tuned for approach)
LOC (tuned for approach)
GPS
two DME stations
one VOR with a co-located DME
IRS
The FMC automatically tunes the VOR, DME, and ILS radios for position updates. In flight, the FMC position continually updates from the GPS, navigation radios, and IRS. Updating priority is based on the availability of valid data from the supporting systems.

20. Navaid updating vs. ANP
The FMC position is always starts with the IRS position. The position is then updated using the best available sensors. Notice how the Actual Navigation Performance changes with different sensor combinations.

21. FMC Position Updating Indication
Notice as long as GPS is available, GPS is the source of updating unless you are on a localizer approach.
This says the FMC is using GPS updating.
You can identify the source of FMC position updating on the POS REF page 2. The type of radio updating available and tuned navaids is indicated in the bottom right of the page. Because the airplane’s navigation sources and sensors are not perfect, a difference, or error, may exist between the estimated airplane position and the actual airplane position.

22. ANP Concept
95% probability circles of position
An ANP value of 0.06 nm means that the airplane very probably is within a 720 ft diameter circle of its estimated position.
Radio Navigation updating is within a 2 mile diameter circle
The IRS position updating is within a 7.8 mile diameter circle.
ANP is Navigation System Performance- It is affected by what sensors (GPs, Radio etc. are available)
The navigation system performance or actual navigation performance (ANP) indicates how well the airplane position, as determined by navigation sources, matches the true airplane position. If system failures or flight crew selections reduce the number, or degrade the quality, of the navigation sources, ANP increases.

23. ANP Value Indications ANP varies depending on the type of sensors
95% probability circles of position
The ANP values for different sensors are indicated on page 2 along with the ANP of the FMC based on the sensors used for updating. Selecting the 6R switch changes the position indication of the different sensors from a lat/long position to a place / Bearing from the FMC position.

24. HSI Indication Airway limits (not shown on HSI) FMC LNAV Route
This is what you see on the HSI when flying an LNAV route; a magenta line with the airplane (triangle) on the route.

25. ANP Error ANP FMC LNAV Route “Actual (desired)” Route
What you see on the HSI
What is real
ANP
Not shown
FMC LNAV Route
“Actual (desired)” Route
Any navigation system error (ANP) is like shifting the airplane position and LNAV route off of the desired route. In other words the whole map is shifted.

26. FTE Error ANP + FTE = Total Error Total error FTE ANP
“Actual” airplane position
FMC LNAV Route
“Actual” Route
The amount we are actually off the LNAV route is called flight technical error (FTE). This is the flying error. Any flying error away from the magenta line (FTE) can add to the total error. So the potential off track error is the sum of the ANP and FTE.

27. FTE Indications
Oops!
The only indications we have are the airplane symbol off the LNAV route for large deviations and the progress page 2. On arrivals and departures it is recommended to have the range on 10 to allow better visual monitoring of FTE.

28. Flip it around ANP squeezes the allowable FTE
.94nm
.94nm
.06nm
.06nm
So if the ANP is .06, then we must have XTK less than 0.94
Since the error is the sum of the ANP and FTE, an easier way to look at it for operational purposes is to say that as the ANP increases, it reduces the amount we can actually fly off the LNAV route and still maintain our accuracy limit.

29. Required Accuracy 1 RNAV 1 RNP 1
AWESOME MAINTENANCE
NAV SYS FLAWLESS
GOOD POSITION UPDATING
AWESOME MAINTENANCE
NAV SYS FLAWLESS
GOOD POSITION UPDATING
If it’s RNAV 1 you must have the required equipment operational. If it’s RNP 1, then you must ALSO have the RNP set up in the FMC that will alert you if the inaccuracy becomes greater than 1 nm.

30. Airplane - RNP RNP Value Changes during flight
Default RNP displays if no RNP is available from the navigation database or has not been manually entered
Procedure RNP values (from the Navigation database) automatically display when on a procedure
Manually entered RNP remains until changed or deleted. (Large Font)
You need to setup the RNP during RNP operations so the airplane can tell you when it can’t meet it’s requirements. Note it’s better to not manually enter an RNP value if the procedure has already updated the RNP. This allows the RNP to change during a missed approach or changed procedure. Let’s now take a look at managing the different sources of error.

31. RNAV 1 or RNP 1 Example The Sum of ANP and FTE must be less than one
.94nm
.94nm
.06nm
.06nm
So if the ANP is .06, then we must have XTK less than 0.94
If this is an RNAV or RNP 1 procedure, then we want our total error to always be less than one. The larger the ANP gets the less we can be off the centerline and still remain within 1 mile. You can think of it as the ANP reducing the allowable deviation or FTE.

32. Maintaining the Path .06 + .1 = .16 .16 < 1 OK
ANP
ANP
FTE
FTE
.94nm
.94nm
.06nm
.06nm
= .16
.16 < 1 OK
Indication of FTE is on Progress page 2, and ANP on the POS page 2. We are doing fine here.

33. ANP Reaches Limit
ANP
ANP
1 nm
1 nm
If the ANP reaches the limit you cannot guarantee you will still be within 1 nm even if your FTE is zero. If you are in RNP airspace then the RNP alert is set to 1. If you get the UNABLE RNP EICAS message, it’s time to notify ATC. Request radar vectors or a non-RNAV procedure.

34. FTE Reaches Limit
What are we doing out here!
If your FTE reaches or exceeds the limit or the limit minus the ANP, immediately correct back on course.

35. ANP Squeezes Allowable FTE
Note you cannot rely on the “UNABLE RNP” caution message to tell you that your tracking error is too big.
ANP is reducing the allowable flight deviation
It is your job to monitor the total error
Based only on ANP
ANP
ANP
(Flight)
Another way to look at this is as ANP increases the smaller the allowable limit you have to fly. When ANP equals the required accuracy limit, then you are no longer able to ensure that you remain within the tolerance, even if you are right on course. In this case, an EICAS message appears. Next we’ll look at a few parts of the LNAV route.

36. Waypoints Fly-by Fly-over
A waypoint which requires turn anticipation to allow smooth interception of the next segment of a route or procedure
The aircraft navigation system calculates the start of the turn onto the next route leg before the waypoint
A waypoint at which a turn is initiated
The aircraft starts to turn onto the next route leg as it passes over the waypoint
ICAO defines a waypoint as “A specified geographical location used to define an area navigation route or the flight path of an aircraft employing area navigation.” The FMC calculation of a turn depends on the waypoint type. Two types of waypoints are the fly-by and fly-over.

37. Waypoint Trajectory
Both types of trajectory are subject to variations in wind, aircraft speed and bank angle, navigation system logic and pilot or autopilot performance. However, flight paths resulting from fly-by turns are much more consistent and predictable . They are used more often because they require a smaller protected area.

38. Autopilot Bank Angle Control
Recall that we can select autopilot bank angles between 5 and 25 degrees, or we can select AUTO. AUTO enables flight control computer to select bank angle based on airspeed.

39. Turn Delay Effect
Notice the effect of delaying the turn on a fly-by waypoint.

40. Waypoint Use
Fly-by waypoints are the most desirable and therefore most common for many reasons. Fly-over waypoints usually are used because there is a special reason such as terrain separation.

41. Path Terminators
RNAV computers have evolved from straight point to point navigation to using different methods to get to a point, such as climbing to an altitude. Path terminators are the names given to these different methods. You should be familiar with some of these terminators.

42. Path Terminator Codes C I
Path Terminators are coded using two characters:
The first column specifies how the path is flown
The second column specifies how the path is stopped
fly a course
end when the next path is intercepted
Path Terminators are assigned to all RNAV, SID, STAR and Approach Procedure segments in an airborne navigation database. They are named by how the leg is flow to the terminating waypoint for that leg. There are about 23 path terminators. We will briefly look at a few of the most common ones.

43. “Traditional” Waypoint to Waypoint
Track to Fix
The most familiar terminators are the Track to a Fix and direct to a fix. TF Leg defines a great circle track over ground between two known databases fixes. The path to a TF leg could also be an “open” leg to the first waypoint such as a course to fix (CF) or a direct to fix (DF).

44. Open Legs to a Waypoint Direct to Fix Course to Fix
Normal use of the CF is after an FA or CA in a departure or missed approach where it is effective in constraining the track dispersion. The FA/CF (CA/CF) combination can be effective in reducing environmental impact on initial departures.
Direct to a Fix or DF Leg defines an unspecified track starting from an undefined position to a database fix. Course to a Fix or CF Leg defines a specified magnetic course to a database fix. Let’s now look at one last path terminator that is revolutionizing approaches.

45. Radius to Fix (RF)
RF legs are waypoints connected by a constant radius course similar to a DME arc. These are shown on terminal procedures as a curved track between two or more waypoints. The radius is computed by the RNAV system as the distance from the turn center to the termination waypoint. Conventional turns are much less predictable.

46. RF Leg Considerations
There may be a maximum speed shown on some straight legs or some RF legs of smaller radius. This limitation is critical to observe since the ability of the AFDS to track the RF leg is determined by ground speed and maximum available bank angle. In high tailwinds, the resulting ground speed may cause the maximum bank angle to be reached. In this situation, excessive course deviation may occur if the maximum RF speed is exceeded
Do not begin a procedure by proceeding direct to an RF leg. This may cause excessive deviation when the airplane maneuvers to join the RF leg. Normally there is a track-to-fix leg prior to an RF leg to ensure proper RF leg tracking
If a go-around is executed while on an RF leg, it is important to immediately re-select LNAV to avoid excessive course deviation. GA roll mode is a track hold mode and is not compatible with low RNP operations if left engaged. The pilot flying must continue to track the LNAV course using the map display as a reference until LNAV is re-engaged.
RF legs enhance approaches, especially in areas of limited space such as high terrain. There are some special considerations that need to be followed when on an RF leg. This is one of the reasons for the Approval Required (AR) RNP approaches.

47. RNP Approach
Typically, three general reasons for developing RNP approaches:
New procedures to runways never served by an instrument procedure
Procedures either replacing or serving as backup to existing instrument procedures based on different technologies
Procedures developed to enhance airport access in demanding environments. (These are usually RNP AR APCH or approval required approaches, the old SAAR approach)
Approach concepts cover all segments of the instrument approach, i.e. initial, intermediate, final and missed approach. They will increasingly call for RNP specifications requiring a navigation accuracy of 0.3 NM to 0.1 NM or lower.

48. RNP Approach Criteria Lateral Navigation Vertical Navigation
maintain course within the containment limit
Vertical Navigation
Prior to the FAF, the vertical limit below the path is determined by the minimum altitude at the next (active) waypoint published on the approach chart.
From FAF to MAP vertical deviation limit from path is 75 ft unless approach annotated otherwise
If a deviation above the path occurs, apply the criteria for a stabilized approach to determine the need for a missed approach
Here is some general criteria for RNP approaches.

49. New Skillsets Required
Traditional Procedures
RNAV Procedures
Execution is more demanding
Selecting, identifying and displaying navaids
Following track, distance and timing from raw data
Repeated for each leg
Management is relatively easy
Select the right chart and then follow the execution steps
Execution is relatively easy
Following the GPS guidance from waypoint to waypoint
Management is more complex
Valid database, correct procedure loaded and verified
Autopilot mode selection
Avoidance of gross errors and WIDN? (what’s it doing now?)
Modifying CDU in terminal area
Transitioning to an RNAV world requires increased management skills.

50. Further Information BRNAV/PRNAV
For further information on BRNAV and PRNAV, check the Eurocontrol website . Note that they are under the PBN tab.

51. PBN Airspace Transition Summary
Here’s a review of the nomenclature as current diverse RNAV applications are standardized into the concept of PBN.

52. Summary A basic understanding of: Area navigation concepts
The relationship between RNAV and RNP
How their implementation affects control procedures, separation and phraseology
How RNAV systems work as well as their advantages and limitations
We’ve looked at how area navigation has evolved from the original waypoint to waypoint en-route navigation to performance based navigation. Along the way, new methods are employed to allow area navigation to meet current and future needs. We’ll finish with a couple of questions.

53. Which of these pages do you use to find how far you are off the desired path?
Select the correct answer

54. What is the main difference between RNAV airspace and RNP airspace?
Select the best answer
RNAV is for large accuracy limits and RNP is for small accuracy limits
RNAV airspace is for en-route and RNP is for terminal areas only
RNP airspace requires the RNP value is set correctly on the POS REF page (alerting)
All of the above

55. If the FMC does not have any faults, then it will always meet whatever level of accuracy required by the airspace.
Select the correct answer
True
False

56. What is a path terminator?
Select the best answer
A two-letter code which defines a specific type of flight path along a segment of a procedure and a specific type of termination of that flight path
The last waypoint on the route
The final approach fix
The delete key

57. Module Complete