Why Do I Have to Plot my Position?
To understand this answer it is important to review the concept of “Operational Service Volume”. Operational service volume is that volume of airspace surrounding an ICAO standard airways navigation facility that is available for operational use. Within that volume of airspace, a signal of usable strength. Class I navigation is defined as any en route flight operation conducted in controlled or Class G airspace that is entirely within operational service volumes of ICAO standard ground‑based NAVAIDs (VOR, VOR/DME, NDB). Class II navigation is any en route operation that is not categorized as Class I navigation and includes any operation or portion of an operation that takes place outside the operational service volumes of ICAO standard ground-based NAVAIDs. When operating outside the designated operational service volumes of ICAO standard ground-based NAVAIDs, operators must use LRNS approved to navigate to the degree of accuracy required for the control of air traffic and to avoid obstacles Class II navigation does not address the equipment installed in the aircraft. For any type of navigation within this volume of airspace, the IFR navigational performance must be at least as accurate as the navigational performance required by the FIR’s ATC separation minima for that volume of airspace.
Performance Based Navigation, RNAV vs. RNP
RNAV operations permit flight in any airspace with prescribed accuracy tolerances without the need to fly directly over ground-based navigation facilities. PBN represents a worldwide shift from sensor-based navigation to a navigation performance specification. RNAV requires only accuracy as a measure of the navigation performance. A confusing name change happened when the FAA integrated PBN in 2003. The “RNP” label used prior to the USA’s integration of PBN became an inaccurate title for what the operation really was. “RNAV” has added post-PBN to more accurately describe the specification. RNP (RNAV)-10 is the current and more correct title for this operation. An example of this would be the RNP (RNAV)-10 navigation specifications found in the Pacific, Western Atlantic areas and most recently in the Gulf of Mexico. RNP is RNAV with the addition of an onboard performance monitoring and alerting capability. An example of this would be RNP-4. Performance monitoring and alerting relate to both lateral and longitudinal navigation. “Monitoring” refers to aircraft’s ability to determine positioning error and/or ability to follow the desired path. This is presented to the pilot in terms of Actual Navigation Performance, ANP or Error Position Uncertainty, EPU. “Alerting,” describes the aircraft’s navigation system’s warning feature that a containment limit has been reached. This is usually presented to the pilot with a Caution annunciation of “UNABLE RNP” RNP requirements may limit or restrict certain operations like manual flight by the crew or require a dual system installation. These additional functions allow the pilot the opportunity to intervene in the event of navigation errors and return to 100% containment. Because specific performance requirements are defined for each navigation specification, an aircraft approved for an RNP specification is not automatically approved for all RNAV specifications. Each country will establish an approval process to insure adequate crew training in normal and abnormal procedures and operational contingency procedures. The approval process will also establish MEL requirements and to have countrywide system for investigating events affecting the safety of PBN operations, so as to determine their origin.
“Reliably Fixed” is a Requirement
Once outside Class I navigation operators pick up a requirement to “Reliably Fix” their position once per hour. This is defined in the operational approval issued by the FAA in the form of an OpsSpec or LOA. “Reliably fixed,” as defined in the OpSpecs, is a station passage of a VOR, Collocated VOR and Tactical Air Navigational Aid (TACAN) (VORTAC), or NDB waypoint. A “reliable fix” also includes a VOR/DME fix, an NDB/DME fix, a VOR intersection, an NDB intersection, and a VOR/NDB intersection. A “reliable fix” also includes positioning information obtained from an IFR-certified area navigation system, such as GPS, LORAN-C, or DME/DME updated flight management system.
Position Plotting Means “Reliably Fixed”
An aeronautical chart can provide a visual presentation of the intended route which is defined otherwise only in terms of navigational coordinates. Plotting the intended route on such a chart may reveal errors and discrepancies in the navigational coordinates which can then be corrected immediately, before they reveal themselves in terms of a deviation from the ATC cleared route. As the flight progresses in oceanic airspace, plotting the aircraft's position on a chart will help to confirm (when it falls precisely on track) that the flight is proceeding in accordance with its clearance. However, if the plotted position is laterally offset, the flight may be deviating unintentionally, and this possibility should be investigated at once. Position plotting the aircraft’s progress on a chart can be a useful tool for contingency situations. In the event of a total loss of long range navigation capability, a completed plotting chart will assist in the necessary reversion to dead reckoning. In other contingency situations it can help in assessing separation assurance from other tracks or from high terrain (e.g over Greenland).
Plotting Chart Requirements
Plotting your route on your chart will increase your situational awareness as you execute your trip through oceanic and remote continental airspace. The chart must be of a scale appropriate for plotting. Many charts are of the wrong scale or too small. The Jeppesen North/Mid Atlantic Plotting Charts is a useful compromises between scale and overall chart size; while the NOAA/FAA North Atlantic Route Chart has the advantage, for plotting purposes, of a 1° latitude/longitude graticule. You should use a chart, of appropriate scale, to provide yourself with a visual presentation of your intended route, regardless of your type of long-range navigation system. The plotting chart must include, at a minimum: The route of the currently effective ATC clearance, clearly depicted waypoints using easily recognized symbology and plotted positions at least once and hour. It is useful and common to include graphic depictions of all ETPs, divert airfields and proximity of other adjacent tracks. This plotting is usually accomplished 10minutes or 2˚ after passing each oceanic waypoint so as to capture and mitigate any deviation before 25NM/10NM NAT HLA (Gross Navigation Error defined).
Navigation Log Information
In its simplest form this is a record of the time, distance and heading to the next waypoint. A “Nav Log” is usually part of a computerized flight plan and under normal circumstances is a logical and systematic tracking the flight’s progress and recording the data. This information is then kept with the plotting chart as part of the Journey Logbook. Abnormal situations such as an oceanic re-route or a long-range navigation failure can drive the pilot to manually complete a navigation log and/or use the data derived for DR navigation. Many different forms for this are available for this purpose.
Plotting, Paper or Plastic?
Inside AC 91-70B, Appendix D, paragraph D.2.9 “Ten Minutes After Waypoint Passage”. This paragraph speaks to three different ways to position plot, Paper Chart, Navigation Display or “other approved methods”. The FAA has provided two acceptable methods for cross-checking aircraft position at a point approximately 10 minutes after oceanic waypoint passage, paper charts and Expanded NAV Display methods. Any other method should be approved by your POI before implementation because it’s a change in your international procedures from what you were approved to do. If you are not doing one of the first two, you may find yourself asking for approval of your independent/custom plotting method on the same day you are begging forgiveness after a GNE, LHD or ETA bust. Papercharts are cheap and easy to use. They make great sense if you are crossing just a few times a year. If a large Flt Dept is crossing several times a month, the shear volume of paper used to plan, monitor and document your flights could get unmanageable without some more help. This plotting method is appropriate for all aircraft navigation configurations.
Here is how-to-do “Paper Plotting”
If OpSpec A061 has been issued authorizing use of an Electronic Flight Bag and the principal inspector (PI) has authorized “interactive plotting for oceanic and remote continental navigation,” the EFB application may be used in place of a paper plotting/orientation chart. The current edition of AC 120-76, Authorization for Use of Electronic Flight Bags, provides guidance for operators to develop associated EFB procedures. For part 91 operators, an EFB may be used, provided the criteria and considerations of the current edition of AC 91-78, Use of Class 1 or Class 2 Electronic Flight Bag, are observed.
Here is how-to-do “Navigation Display”” ( This method is appropriate for and available for use in aircraft equipped with an operable FMS):
Here is another option...
ForeFlight, FD Pro and Garmin all will display your cleared and verified routing along with the OTS ( NAT and PAC), diverts and ETPs. There are your requirements from Annex D, AC91-70B w/ CHG #1 . When it comes to plotting, snap an iPad/iPhone picture of the expanded NAV display and the FMC showing ANP, RNP, PPOS and time. There is your plot. This method is well within the FAA’s alternate plotting method. Save all these pictures and compliance documentation into a folder on your company’s server or iCloud/Dropbox for quick retrieval when asked for them.
1. There is no reason that you could not do the same thing as what “Code7700” is doing or something better you can dream up. It will take some dedicated soul to develop and standardize the procedures, hardware and software plus revisions.....BUT get the POI to sign off on it first.
2.When it comes to electronic plotting on the iPad, I have seen a very clever way to stay FAA compliant. Get your NAV display set up like the alternate method in 91-70B. Then have the FMC displaying the NAV DATA or PPOS page to show actual LAT/LOG, TIME and ANP/EPU value. Snap a picture with the iPad camera Now you are FAA compliant and electronically able to prove your FAA approved procedure compliance.
3. Use the paper charts as a BU or in a Contingency.