Part 91 LOA Application Support

CPDLC (Controller-Pilot Data Link Communications)

The CPDLC application provides air-ground data communication for the ATC service. It enables a number of data link services (DLS) that provide for the exchange of communication management and clearance/information/request messages which correspond to voice phraseology employed by air traffic control procedures. The controllers are provided with the capability to issue ATC clearances (level assignments, lateral deviations/vectoring, speed assignments, etc), radio frequency assignments, and various requests for information. The pilots are provided with the capability to respond to messages, to request/receive clearances and information, and to report information. A “free text” capability is also provided to exchange information not conforming to defined formats.

The CPDLC is being globally implemented and currently is in different implementation stages.

Expected Benefits of CPDLC

Less communication on the ATC frequency;

Increased sector capacities;

More pilot requests can be dealt with simultaneously;

Reduced probability of miscommunication (e.g. due call sign confusion);

Safer frequency changes, hence fewer loss of communication events.

Reference:

https://www.skybrary.aero/index.php/Controller_Pilot_Data_Link_Communications_(CPDLC)

Required for an operator to conduct instrument flight rules (IFR) Class I Navigation using an Area Navigation (RNAV) system (GPS).

Precision-Area Navigation (P-RNAV) is the European terminal airspace RNAV [1] application and it is the natural progression from Basic RNAV which became mandatory in European airspace in April 1998. The P-RNAV track keeping accuracy equates to cross track accuracy of RNP1 (+/- 1NM).

Aircraft P-RNAV equipment automatically determines aircraft desired flight path by a series of way points held in a database. P-RNAV procedures are designed to a common set of design principles specific to RNAV equipped aircraft. These procedures will replace the current multitude of RNAV procedures many of which are unsuitable for a wide range of aircraft types. It is recognized that the existing variations in RNAV approval requirements, the variations in procedure design and procedure publication/charting, as well as the variations in navigation data integrity could have considerable safety implications.

P-RNAV offers the ability to use RNAV functionality in all phases of flight except final approach and missed approach. It enables to define routes in the terminal airspace which meet the needs of the aircraft operators and the air navigation services provider. This often means shorter, more direct routes with simple connections to the en-route structure. However, where environmental issues play a major role, the route can be designed to make best advantage of the airspace available and, where possible, by-pass densely populated areas. Careful design can also result in appropriately segregated arrival and departure streams, thereby reducing the need for radar vectors and hence the workload for both the pilot and the controller. Fewer radar vectors also means less uncertainty on the flight deck with regard to the anticipated tactical route and the distance to go.

Difference between B-RNAV and P-RNAV

Basic Area Navigation (B-RNAV) was the forerunner of the RNAV implementation in ECAC. Since 2008, B-RNAV in Europe and RNP 5 in the Middle East were supported in continental en-route airspace by RNAV applications. In the United States, RNAV 2 supports en-route continental airspace. B-RNAV was introduced to enable en route capacity gains to be achieved with minimal aircraft capability. It requires aircraft conformance to a track-keeping accuracy of +/-5 NM for at least 95% of flight time. This level of navigation accuracy is achieved by using DME/DME, GPS or VOR/DME.

Implementation of P-RNAV

A mandate for carriage of P-RNAV in the ECAC area is not foreseen. However European States will progressively introduce P-RNAV requirements for Terminal RNAV procedures. These procedures should be consistent in the various ECAC States, based on a common set of design and operation principles, ensuring consistent levels of flight safety.

Since November 2005, aircraft operating on RNAV terminal area procedures in major ECAC terminal airspaces were subject to the following requirements

For RNAV procedures which include route segments below the appropriate Minimum Flight Altitude (e.g. Minimum Sector Altitude (MSA); Minimum Radar Vectoring Altitude (MRVA)), P-RNAV approval will be required.

For RNAV procedures which do not include route segments below the appropriate Minimum Flight Altitude (e.g. Minimum Sector Altitude (MSA); Minimum Radar Vectoring Altitude (MRVA)), and designed in accordance with en-route design principles, B-RNAV approval may suffice. Otherwise, except where explicitly stated that the carriage of P-RNAV certified equipment is not required, the only acceptable alternative for such RNAV procedures is P-RNAV.

As of 2008, the United States terminal airspace application formerly known as US RNAV Type B has been aligned with the PBN concept and is now called RNAV 1. Basic RNP 1 has been developed primarily for application in non-radar, low density terminal airspace. In future, more RNP applications are expected to be developed for both en-route and terminal airspace.

Reference:

https://www.skybrary.aero/index.php/Precision-Area_Navigation_(P-RNAV)

Required for Oceanic and Remote Operations

Required navigation performance (RNP) is a type of performance-based navigation (PBN) that allows an aircraft to fly a specific path between two 3D-defined points in space. Area navigation (RNAV) and RNP systems are fundamentally similar. The key difference between them is the requirement for on-board performance monitoring and alerting. A navigation specification that includes a requirement for on-board navigation performance monitoring and alerting is referred to as an RNP specification. One not having such a requirement is referred to as an RNAV specification. Therefore, if ATC Radar Monitoring is not provided, safe navigation in respect to terrain shall be self-monitored by the pilot and RNP shall be used instead of RNAV.

RNP also refers to the level of performance required for a specific procedure or a specific block of airspace. An RNP of 10 means that a navigation system must be able to calculate its position to within a square with a lateral dimension of 10 nautical miles. An RNP of 0.3 means the aircraft navigation system must be able to calculate its position to within a square with a lateral dimension of 3/10 of a nautical mile.[1] The differences in these systems are typically a function of on-board navigational system redundancies.

A related term is ANP which stands for “actual navigation performance.” ANP refers to the current performance of a navigation system while “RNP” refers to the accuracy required for a given block of airspace or a specific instrument procedure.

Some oceanic airspace has an RNP capability value of 4 or 10. The level of RNP an aircraft is capable of determines the separation required between aircraft with respect to distance. Improved accuracy of on-board RNP systems represent a significant advantage to traditional non-radar environments, since the number of aircraft that can fit into a volume of airspace at any given altitude is a square of the number of required separation; that is to say, the lower the RNP value, the lower the required distance separation standards, and in general, the more aircraft can fit into a volume of airspace without losing required separation. This is not only a major advantage for air traffic operations, but presents a major cost-savings opportunity for airlines flying over the oceans due to less restrictive routing and better available altitudes.

Reference:

https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/media/NAS.pdf

Required to have if crossing North Atlantic on the North Atlantic Track System

The airspace of the North Atlantic (NAT), which links Europe and North America, is the busiest oceanic airspace in the world. In 2012 approximately 460,000 flights crossed the North Atlantic and that volume of traffic continues to increase. Direct Controller Pilot Communications (DCPC) and ATS Surveillance are unavailable in most parts of the NAT Region. Aircraft separation, and hence safety, are ensured by demanding the highest standards of horizontal and vertical navigation performance/accuracy and of operating discipline.

The vertical dimension of NAT HLA Airspace: Between FL285 and FL420 (i.e. in terms of normally used cruising levels, from FL290 to FL410 inclusive).

North Atlantic Tracks, officially titled the North Atlantic Organised Track System (NAT-OTS), is a structured set of transatlantic flight routes that stretch from the northeast of North America to western Europe across the Atlantic Ocean. They ensure aircraft are separated over the ocean, where there is little radar coverage. These heavily traveled routes are used by aircraft traveling between North America and Europe, flying between the altitudes of 29,000 and 41,000 feet inclusive. Entrance and movement along these tracks is controlled by special Oceanic Control Centres air traffic controllers to maintain separation between airplanes. The primary purpose of these routes is to allow Air Traffic Control to effectively separate the aircraft. Because of the volume of NAT traffic, allowing aircraft to choose their own co-ordinates would make the ATC task far more complex. They are aligned in such a way as to minimize any head winds and maximize tail winds impact on the aircraft. This results in much more efficiency by reducing fuel burn and flight time. To make such efficiencies possible, the routes are created twice daily to take account of the shifting of the winds aloft and the principal traffic flow, eastward in North America evening and westward twelve hours later.

Reference:

https://www.skybrary.aero/index.php/North_Atlantic_Operations_-_Airspace

https://www.faa.gov/about/office_org/headquarters_offices/avs/offices/afs/afs400/afs470/media/NAT.pdf

LOA C052 is not needed for operations within the United States or territories for part 91 operators. Some foreign nations have requested evidence of training and approval to fly Global Navigation Satellite System (GNSS)-based approaches to Localizer Performance with Vertical Guidance (LPV) minima. An optional LOA template is provided to satisfy a request from foreign regulatory authorities for evidence of training and approval to fly GNSS-based approaches. This LOA can satisfy that request. A similar approach was taken with optional LOA C063, Area Navigation (RNAV) and Required Navigation Performance (RNP) Terminal Operations.

Reference:

http://fsims.faa.gov/wdocs/8900.1/v03%20tech%20admin/chapter%2018/03_018_005.htm

For part 91 operators, this letter of authorization is not required and is optional.

Some foreign nations have requested evidence of training and approval to fly Global Navigation Satellite System (GNSS)-based approaches to Localizer Performance with Vertical Guidance (LPV) minima. An optional LOA template is provided to satisfy a request from foreign regulatory authorities for evidence of training and approval to fly GNSS-based approaches. This LOA can satisfy that request. A similar approach was taken with optional LOA C063, Area Navigation (RNAV) and Required Navigation Performance (RNP) Terminal Operations.

Reference:

https://www.faa.gov/documentLibrary/media/Notice/N_8900_348.pdf

Minimum Equipment List (MEL). The MEL is the specific inoperative equipment document for a particular make and model aircraft by serial and registration numbers. For example, PA 28-181, N12345. A Part 91 MEL consists of the Master Minimum Equipment List (MMEL) for a particular type aircraft, the preamble for Part 91 operations the procedures document, and a Letter of Authorization (LOA). The FAA considers the MEL as a supplemental type certificate (STC). As such, the MEL permits ope Letter of Authorization (LOA). The flight standards district office (FSDO) issues an LOA to an operator when the FSDO authorizes an operator to operate under the provisions of an MEL. Together, the LOA, the procedures document, and the MMEL constitute a supplemental type certificate (STC). The operator must carry the STC in the aircraft during its operation. If a fractional ownership is involved, the LOA will be issued to the management company. Each individual owner will not be listed in the LOA.

A minimum equipment list (MEL) is a list which provides for the operation of aircraft, subject to specified conditions, with particular equipment inoperative (which is) prepared by an operator in conformity with, or more restrictive than, the MMEL established for the aircraft type. (ICAO Annex 6: Operation of Aircraft)

The master minimum equipment list (MMEL) is a list established for a particular aircraft type by the organisation responsible for the type design with the approval of the State of Design which identifies items which individually may be unserviceable at the commencement of a flight. The MMEL may be associated with special operating conditions, limitations or procedures. (ICAO Annex 6: Operation of Aircraft)

The operator shall include in the operations manual a minimum equipment list (MEL), approved by the State of the Operator which will enable the pilot-in-command to determine whether a flight may be commenced or continued from any intermediate stop should any instrument, equipment or systems become inoperative. Where the State of the Operator is not the State of Registry, the State of the Operator shall ensure that the MEL does not affect the aeroplane’s compliance with the airworthiness requirements applicable in the State of Registry. (ICAO Annex 6 Part I Chapter 6 Para 6.1.1)

An operator may not operate an aircraft which does not comply with the approved MEL, except with the explicit permission of the Appropriate Regulatory Authority, usually the NAA. Such permission will not be granted to allow the aircraft to operate outside conditions set by the corresponding MMEL.

Reference:

https://www.faa.gov/regulations_policies/advisory_circulars/index.cfm/go/document.information/documentID/22435

http://www.skybrary.aero/index.php/Minimum_Equipment_List_(MEL)

MINIMUM EQUIPMENT LISTS: FAA APPROVAL DOES NOT ENSURE INTERNATIONAL COMPLIANCE

Using a D095 to fly internationally, especially to Europe, requires additional attention.

It’s important to understand that a Part 91 MEL approved under D095 consist of the following elements:

The FAA D095 LOA, which authorizes the operation of the aircraft specific to the aircraft make, model, serial number and registration number;

The MEL procedures document, developed by the aircraft operator and including maintenance and operations (M&O) procedures;

Policy Letter PL 36, the Part 91 master minimum equipment list (MMEL) preamble, obtained from the FAA Flight Standards Information Management System (FSIMS) website; and

The MMEL itself, as developed by the aircraft manufacturer and the FAA.

Combined, these four components create an MEL for Part 91 operations approved by the FAA using D095. All four parts must be kept on the aircraft to comply with the D095 LOA. The MEL procedures document is developed by the operator, typically using guidance provided by the manufacturer (e.g., a dispatch deviation guide). Third-party resources are often helpful in developing a procedure document tailored to your aircraft and operation, and then packaging each of the above items into a complete MEL document.

Reference:

https://www.nbaa.org/ops/intl/eur/20170324-preparing-for-european-ramp-inspections.php

Part 91 Requirements. Operators conducting part 91 operations:

1. May use the Master Minimum Equipment List (MMEL) as an MEL, in accordance with the letter of authorization (LOA) D095.
2. May choose to use an FAA-approved MEL in accordance with LOA D195.
3. Developing an aircraft-specific MEL, approved through LOA D195, is another option for ensuring that your MEL is acceptable to EASA inspectors

Some countries no longer all D095 MMEL (Master MEL used as an MEL). D195 would be required for operations into these countries. Fly Certs LLC can develop aircraft specific MEL’s for your individual aircraft.