LT Horizontal Vertical 30° \ Horiz C/L VJ 0 30° 15 NOM RT ON AC 29-2C, Chg 7 2/4/2016 Figure AC 29 MG 19-2 Secondary Field of View
(4) System.
(i) Electrical system information required by § 29.1351 and other system information, like integrated caution and warning messaging that may be included in an EICAS display, may also be displayed in the secondary field of view providing there is a master caution and/or warning light in the pilots’ primary field of view.
(ii) EDSs provide the ability to present system information on separate pages of a display. System architecture should not allow deselecting of the PFD, thereby not allowing access to system pages on MFDs.
(iii) The EDS design should inhibit access to configuration and maintenance pages in flight. However, pilots should have access to all information they need to perform their normal and any non-normal procedures.
(iv) The EDS design and installation should inhibit any pilot or manually initiated built-in-test of the EDS in-flight.
d. Display of Information.
(1) Format.
(i) See SAE ARP 4102-7 for examples of display formats. If new or novel formats are developed, coordinate with the certificating authority early in the certification project. Issue papers and, possibly, equivalent level of safety findings may be required.
(ii) Information format should allow the pilot quick access to the information presented without confusion or concentration. The format of the information is influenced by the type of information the display should relay to the pilot.
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(A) There needs to be graphical display of parameters for information containing rate or that can be dynamic in nature. Additionally, graphical display of parameters provides both discrete and spatial information to the pilot. It shows the pilot where the parameter is relative to limits as well as the specific value. Additionally, graphical displays allow the pilot to see changes spatially, as opposed to relying on remembering a numerical value and comparing it to the present numerical value.
(B) Numerical display of information is useful for static information that does not change or for pilot-selected discrete parameters. Additionally, if the parameter does not need to convey information regarding rates of change or position relative to a limit, then it may be acceptable to display it numerically.
(iii) Failure indications of loss of information should be clear, unambiguous, and not misleading. For example, it has been effective to use a red “X” with failure indication or the graying out of a failed parameter with failure indication. Removal of the indication upon failure without other symbology can cause confusion. Regardless of the method used to indicate a failed parameter, it should be intuitively obvious that the information is neither available nor misleads the pilot.
(iv) The format should inform the pilot with indications of flight guidance, attitude, airspeed, and altimeter information sources. For systems with redundant sources, where the system monitors and compares data between the systems, indications should alert the pilot of a mismatch and an indication to the use of whether the data sources are “offside” or “onside.” Switch position alone should not be used to indicate selection of the system.
(2) Colors.
(i) Develop the color philosophy early and apply it consistently throughout the instrument displays. SAE ARP 4102-7 contains information regarding color schemes.
(ii) Color should not be the sole method of coding to account for pilot color vision deficiencies. Use of redundant coding such as shape, outline, flashing, reverse video, or auditory is encouraged. However, flashing use should be limited. If applied, the use of flash coding should be consistent. For example, flashing should not be a caution for one parameter and a warning for another.
(iii) Colors used to alert pilots must follow the requirements in § 29.1322.
Also, consider AC 25.1322-1 regarding color use guidance. However, coordinate with the applicable certificating authority prior to adopting AC 25.1322-1 guidance.
(A) The color red must be reserved for alerting functions requiring immediate pilot awareness and action. Red is required to be used when marking limits on instruments and gauges. See section 29.1543 and subsequent sections of this AC for further guidance on the use of colors. Additionally, red may not be used to alert the pilot that a system is functioning normally in an emergency situation.
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AC 29-2C, Chg 7 2/4/2016
(1) Red should not be used as an outline for instruments or gauges.
Nor should red be used to define areas or “windows” on displays.
(2) Graphical displays of powerplant parameters should not present red bands or arcs. The marking of limits must comply with § 29.1547.
(B) The color scheme on moving map displays, navigation displays, and terrain displays should be the same. This is important to decrease pilot confusion and the possibility of providing misleading information.
(iv) Consider using the color schemes shown in the below tables.
Recommended Colors for Certain Functions Feature Color Warnings Red Flight envelope and system limits, exceedances.
Red or Yellow / Amber as appropriate (see above) Cautions, non-normal sources. Yellow / Amber Scales, dials, tapes, and associated information elements.
White Earth Tan / Brown Sky Blue / Cyan Engaged Modes/normal conditions. Green Glide path and course deviation indicators. Magenta/Green Flight directors or “fly-to” indicators Magenta Divisor lines, units and labels for inactive soft buttons.
Light Gray Specified Colors for Certain Display Features Display Feature Color Set 1 Color Set 2 Fixed reference symbols White White* Current data, values White Green Armed modes White Cyan Selected data, values Green Cyan Selected heading Magenta* Cyan Active route/flight plan Magenta White * Use of other colors for this function may be acceptable as long as they are not flightcrew alerting colors used for conditions that may require pilot action or indicate abnormal conditions.
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(3) Symbology.
(i) One benefit of symbol standards versus other information formats is the compact encoding of information, which minimizes clutter. With careful planning, base the use of symbols upon established industry standards. SAE ARP 4102/7 and ARP 5289 standards provide examples of accepted symbols and symbol sets for PFDs and MFD-navigation displays.
(A) Symbolic encoding of information should remain sufficiently simple for pilots to learn and recall (see section AC 29 MG-20, Human Factors, of this AC). To minimize confusion or misinterpretation, symbols should be easily distinguishable, consistent within the cockpit, and learned with minimal training.
(B) Symbols should not have shapes, colors, or other attributes that are ambiguous or could be confused with the meaning of similar symbols.
(C) The function of symbology should be clear definition and appropriate classification for pilot understanding. Symbols representing the same functions on more than one display should be the same.
(ii) HTAWS, automatic dependent surveillance-broadcast (ADS-B), TCAS, and other applications each have their own defined symbol sets. If these features are included in the installation and will use the EDS displays to show information, then the EDS should use each application’s (HTAWS, ADS-B, TCAS, etc.) defined symbol set.
Assess the symbol sets to ensure they do not contain similar symbology with different meanings.
(iii) The EDS design and integration should provide a means to reduce or “declutter” the EDS of non-essential symbology.
(4) Clutter.
(i) Computer generated displays provide the ability to present a multitude of information. As a result, numerous formats are possible with an electronic display system. However, excessive information on a limited display size can result in clutter, resulting in reduced efficiency of pilot cues, pilot scan, and detection.
(A) The density of information on the display should be compatible with the pilot's ability to recognize essential information and to minimize misinterpretation. At times, pilots may wish to reduce clutter by removing the display of symbols otherwise used during specific phases of flight.
(B) There should be an information prioritization scheme established to ensure the clear presentation of essential information.
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AC 29-2C, Chg 7 2/4/2016 (C) If anticipating clutter, there should be a means provided for manual decluttering. Automatic de-cluttering, such as during specific phases of flight, or during certain alerts, may also be appropriate.
(ii) Clutter should be a major consideration during the reversionary or compacted display modes. When combining essential information on a display after another display or unit fails, the display format should not be confusing and the information should still be usable, including ability to display unusual attitudes.
(iii) Unusual attitude and de-cluttering of the PFD.
(A) All primary attitude displays should provide an immediately discernable attitude recognition capability that fosters a safe and effective unusual attitude recovery capability. The display should provide sufficient cues to enable the pilot to maintain fulltime attitude awareness and minimize potential for spatial disorientation.
(1) The display should support the initiation of recovery from unusual attitudes within 1 second with a minimum correct response rate of 95 percent.
(2) Additional information included on primary flight reference displays should not interfere with maintaining attitude awareness, recovering from an unusual attitude, or the interpretation of any primary flight information. Consider removing information not used in unusual attitude recovery.
(B) Annunciations and Indications.
(1) General. Annunciations and indications include annunciator switches, messages, prompts, flags, and status or mode indications, which are on the flight deck display itself or control a flight deck display. Refer to § 29.1322 for specific annunciations and indications such as warning, caution and advisory level alerts.
(i) Annunciations and indications should be operationally relevant and limited to minimize the adverse effects on flightcrew workload.
(ii) Annunciations and indications should be clear, unambiguous, and consistent with the flight deck design philosophy. When providing annunciation for the status or mode of a system, the annunciation should indicate the actual state of the system and not just the position or selection of a switch. Annunciations should only be indicated while the condition exists.
(2) Location. Annunciations and indications should also be consistently located in a specific area of the electronic display. Annunciations that may require immediate flightcrew awareness should be located in the flightcrew’s forward, primary field of view. There may be CAS messaging presentation in the pilot’s secondary field of view if there is a Master Caution/Warning indicator.
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(3) Attention-getting cues: When selecting the type of attention- getting cue, a text change by itself is typically inadequate to annunciate automatic or uncommanded mode changes.
(i) Use audio tones or voice messages. Keep the number of different tones to a minimum to decrease the possibility of confusion. Aircrew alerts are more noticeable when a combination of audio tone or audio message and a visual cue is used.
(ii) Blinking or Flashing. Blinking information elements such as readouts or pointers can be effective methods of annunciation. However, the use of blinking or flashing should be limited because it can be distracting and excessive use reduces the attention-getting effectiveness. Use blinking rates between 0.8 and 4 hertz, depending on the display technology and the compromise between urgency and distraction. If blinking of an information element can occur for more than approximately 10 seconds, there should be a means provided to cancel the blinking.
(5) Flight and Navigation Display of Information on the PFD.
(i) Flight. At a minimum, the primary flight display portion of the PFD should displays the attitude, airspeed, altitude, and heading. Most EDS flight displays also include navigation guidance in the form of course deviation, and if applicable, vertical glide path deviation. They can also include information on vertical speed indications, radar altitude, and flight guidance mode. If synthetic vision (SV) is incorporated, it should be on the flight display as a “pilot-view out the window” (egocentric) format. If incorporating SV into the flight display, it should provide the same level of accuracy and validity as the other navigation sources. If displayed on the PFD, describing the SV’s intended function as “situational awareness only” or “not required” to justify a lower design assurance level is not acceptable.
(A) Information.
(1) PFI refers to those functions or parameters that are required by the airworthiness and operational regulations such as airspeed, altitude, attitude, and heading (direction). 14 CFR part 29 requires attitude, airspeed, altitude, and heading (direction) as PFI. Most EDS designs include attitude, altitude, airspeed, and heading display in the basic “T” arrangement as defined in § 29.1321. There are specific requirements contained in TSOs for the display of each of these parameters.
Note: TSO approval does not authorize installation of a system or instrument into a rotorcraft. The installation of an instrument or system must meet the certification requirements for the rotorcraft. For example, some attitude indicators carry TSO-C4 approvals but are not qualified for installation in rotorcraft where an ADI is required by the certification rules.
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AC 29-2C, Chg 7 2/4/2016
(2) Part 29 category A and non-category A rotorcraft certificated to operate under VFR only may require secondary sources of PFI if the failure hazard assessment and system safety assessment (FHA/SSA) shows that the failure condition classification warrants redundancy. For most installations, there is a requirement for a second attitude, altimeter, and airspeed indicator.
(3) PFI for IFR Rotorcraft
(i) For IFR rotorcraft, part 29 Appendix B (viii) drives the PFI requirements (refer to Appendix B of this AC for more information). If using an integrated electronic display as a secondary source or standby instrument, there should be arrangement of the PFI in the basic T-configuration on the display. Additionally, PFI is considered essential for safe operation and should meet minimum standards of applicable TSOs or equivalent and meet the requirements of § 29.1309 and part 29 Appendix B, if applicable. There should be clustering and arrangement of the electromechanical standby instruments to allow the pilot use of them without undue concentration.
(ii) Gyroscopic pitch and bank ADI presentation should meet the requirements of § 29.1303(g)(1) regardless of whether or not they are considered standby ADIs. Section 29.1303 of this AC explains the requirements for an ADI to comply with § 29.1303(g)(1).
(B) Arrangement
(1) 14 CFR 29.1321 specifies placement of information relative to the pilot’s field of view. Refer to, section 29.1321 of this AC for further guidance.
(2) Most EDS displays follow the traditional “T” arrangement described in Appendix B of this AC and 14CFR 29.1303. Deviations from this arrangement should be coordinated early with the certification authority.
(3) Depending on design, addition of information normally found on EICAS or other MFDs, such as power instruments or CAS messages, may be included.
If this is the case, early human factors evaluation for clutter, information density, and format and function of non-flight information should be accomplished on bench tests and in a simulator (if available) or on in-flight evaluations.
(C) Format and function.
(1) Display of Attitude:
(i) Most EDS displays format attitude in a conventional manner.
Alternate display formats and functions considered should be coordinated early with the CA. Pitch, bank, horizon line and indicators, and the aircraft symbol should be clear and easily acquired to allow the pilot quick access to the aircraft’s attitude in all Page MG 19 -22
operating conditions. Regardless of added guidance or navigation cues, there should still be the ability for the accurate assessment of the attitude by the pilot.
(ii) For flights under IFR conditions, some VFR at night operational rules, (e.g., 14 CFR parts 91 and 135) require an attitude indicator. The loss of all attitude information or the presentation of misleading of attitude information could result in a catastrophic hazard condition where the pilot could not continue safe flight and landing of the rotorcraft. As a result, depending on the whether the rotorcraft is VFR or IFR certificated, the design assurance level of the EDS PFD should be commensurate with the assessed FHA failure condition classification for loss of and misleading attitude information. In addition, flight at night in a VFR rotorcraft, especially one without a stabilization system may lead to a higher failure condition classification than for day VFR.
(iii) Additionally, the same operational rules require VFR rotorcraft provides ADI requirements for those operations. If an ADI is required, it must meet and be installed in accordance with § 29.1303. See AC 20-2C and § 29.1303 for guidance on ADI requirements. Section 29.1303 of this AC explains the requirements for an A DI to meet § 29.1303(g)(1).
(iv) Additional considerations. When the true horizon is no longer on the display, the artificial horizon line should provide a distinctive demarcation between sky and ground (or the background). The horizon reference l ine on the PFD should be at least 3.25 inches wide in straight and level flight for integrated displays.
This recommendation does not prevent replacement of mechanical instruments with electronic displays of similar horizon reference line.
(2) Display of Altitude.
(i) Consider primary display of altitude to be barometric altitude.
The altitude display format should be clear and easily interpreted by the pilot. If the EDS allow selection of alternate display modes such as switching between feet and meters, then clearly display the active mode to the pilot to avoid confusion. Additionally, if selection between HPa and inches Hg in the Kollsman Window is selectable, the selected mode must be clear and easily interpreted by the pilot.
(ii) Display of Global Navigation Satellite System (GNSS) altitude.
The simultaneous display of GNS and barometric altitude is not recommended. If there is a mode to display GNSS or GPS derived altitude, the display of GPS altitude should be distinctly different from barometric altitude so there can be no confusion regarding the source. Additionally, there should be clear labeling of the GNSS altitude. One acceptable label is “GSL.”
(iii) Radar or radio altitude (RALT). RALT is required for certain operations. If the integrated display system has the ability to provide RALT displays, there should be consideration given to the intended function of the RALT in rotorcraft. A Page MG 19 - 23
AC 29-2C, Chg 7 2/4/2016 strictly numerical readout of RALT may not be sufficient to provide the intended function based on operations. Conversely, a graphical display of RALT, depending on the implementation, may create confusion. For example, incorporating a ground reference cue based on RALT into a barometric altitude display could lead to confusion if not supplemented by another cue.
(iv) The use of moving tape displays or graphical representation of traditional round dial altimeters has been equally effective. Linear tape altimeter displays should include enhancements denoting standard 500 and 1,000-foot increments, and they should convey the present altitude unambiguously and at a glance. The combination of altimeter scale length and markings, therefore, should be adequate to allow sufficient resolution for precise manual altitude tracking in level flight, as well as enough scale length and markings to reinforce the pilot’s sense of altitude.
The scale length should also allow sufficient look-ahead room to adequately predict and accomplish level off. Pilot evaluations have shown that, in addition to the appropriate altitude markings commensurate with rotorcraft performance, the recommended use of an altitude reference bug provides acceptable cues.
(A) A trend indicator should be displayed unless a vertical speed indicator (VSI) is located adjacent to the altimeter. A six-second altitude-trend indicator is typical, but other trend values may be more appropriate depending on the rotorcraft performance and altitude tape scaling.
(B) Some operations require an instantaneous VSI. If installed, ensure it functions correctly and provides the pilot with usable information. Some instantaneous VSI installations may be unusable due to jittery performance.
(ii) Navigation. The navigation display (ND) portion of the PFD and a MFD can display navigation information. This section focuses on the navigation information displayed on the navigation display portion of the PFD. Guidance on information presented on the navigation display is contained in SAE ARP 4102-7. Appendix B to SAE ARP 4102-7 provides navigation symbology guidance. Certain information should also be included on the ND. Navigation source (GPS, VOR1, LOC, etc.), waypoint name, and distance-to are types of information the ND should display, particularly if envisioning RNAV approaches. ND displays have also contained primary powerplant information either as individual instruments (torque (TQ), turbine temperature (TOT), or turbine speed (Ng, N1 %RPM)) or as an integrated first limit indicator or power indicator display. Additionally, main rotor RPM (NR), and free turbine speed (Np, NF, N2 %RPM) may be displayed on the ND.
(A) Arrangement.
(1) Normally, the HSI or compass rose is in the middle of the ND with the other information arrayed around it.
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(2) Active navigation information (waypoint name, etc.), should be as close to the top of the display as possible to minimize the pilot’s scan between the PFD and ND.
(B) Format.
(1) The HSI or compass rose format should have a full 360o display. If an arc feature is included, the arc should display at least 120o of heading. In arc mode, if the heading bug is off the display, there should be a means to indicate to the pilot what heading the bug is set on.
(2) The rest of the displayed information format should allow for easy assessment and interpretation by the pilot.
(3) Overlays of TCAS, HTAWS, or weather information should not interfere with the use of the ND for primary navigation tasks. There should be definition of the prioritization of overlay pop-ups, if installed.
(6) Powerplant and Systems Information.
(i) Powerplant. EDS display suites may or may not include the capability of displaying powerplant parameters required by § 29.1305 along with electrical system information required by § 27.1351and hydraulic system information required by § 29.1435. Displaying powerplant information on a single display, as opposed to displaying the information in separate gauges, decreases the independence of information. As a result, EDS powerplant display (EICAS, IIDS, etc.) design should be robust enough so that information availability and validity is commensurate with the assessed FHA failure condition classification.
(A) Arrangement.
(1) 14 CFR 29.1321 and Appendix B (VIII) to part 29 specify placement of information relative to the pilot’s field of view. Refer to section 29.1321 and Appendix B of this AC for further guidance.
(2) Torque, power turbine temperature, power turbine speed, main rotor speed, and free turbine speed should continuously display in the pilot’s primary field of view. The format for these parameters can vary and is discussed below.
(3) Display of engine oil temperature and pressure and main gearbox oil temperature (and pressure if required) should continuously display. If positioned in the pilot’s secondary field of view, they should be as close to the pilot’s primary field of view as possible.
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AC 29-2C, Chg 7 2/4/2016 (B) Format. EDS provides the ability to display powerplant information in a variety of formats. For EDS installed to replace analog gauges, the format of the primary powerplant instruments (TQ, N1, TGT) should allow pilots to easily transition from the old analog variant to the digital variant without undue concentration and without training.
(1) Gauge layout and marking should be easy to see and interpret.
(i) If using a similar format such as round-dial representation of a round dial analog gauge, then indices and markings should be similar to the analog gauge the digital display is replacing. This is to ensure there is no negative transfer from reading traditional electromechanical gauges or confusion when reading the digital gauge. There may be improvements made over the existing gauges. For example, an instrument such as a dual tachometer, which provides information on the status of main rotor speed, may also provide information relating to pilot collective input (to correct a deviation in rotor RPM). For example, providing a dual tachometer that places the normal range at the 9:00 position provides the pilot with two types of information. If the rotor RPM is high, the needle is high. It also gives the pilot a cue that to lower the RPM, the pilot should lower the collective to lower the NR (and bring the needle down to the normal range).
(ii) Use of a distinctly different format such as a tape or linear gauge or a distinctly different shaped representation should allow for quick and easy assessment of information. The ease of use should be better or the same upon gauge replacement.
(iii) Needles, pointers, or other indicator means should point at the value, not cross or obscure the value. If using multiple needles or pointers on a display, the parameter that they are indicators for should be clear and easily distinguishable from the others on the display.
(iv) Markings must follow requirements of §§ 29.1543 through
29.1555.
(2) Graphical and numerical-only displays of parameters or information should follow the guidance in section d above. Providing a numerical readout along with graphically presented information provides the pilot with complementary data of a specific value coupled with the awareness of where in the operating range that value resides.
(i) There should be graphical display of powerplant pressures and temperatures, fuel levels and pressures, and speeds.
(ii) There should also be graphical presentation of other parameters with a range of normal if the pilot needs to monitor where a parameter is or is changing relative to a limit.
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(C) Part-time vs. full-time display of information.
(1) Powerplant instruments required by § 29.1305 should be displayed full time (i.e., continuous display). However, due to space limitations or display system design, EDS displays that allow for the de-selection of secondary powerplant instruments (e.g., engine oil temperature and pressure, transmission oil temperature, electrical and hydraulic system information) required by § 29.1305, may be acceptable.
There should be continuous display of primary power information (TQ, MGT, Ng, or their equivalents) and Rotor tachometer (Nr and Np).
(i) In order to allow the de-selection or part-time display of these parameters, compensatory features should be designed and provided to alert pilots to select and monitor § 29.1305 instruments prior to the parameter reaching a cautionary or warning limit.
(A) Algorithms and monitoring software can provide the capability to alert pilots about possible anomalies in a parameter’s behavior. Pilots can then select the appropriate display, monitor the situation, and mitigate the situation as required prior to it becoming an abnormal condition.
(B) The monitoring function should automatically provide the same level of monitoring that would exist if there were continuous display of the individual engine gauges.
(ii) To show compliance using part-time display of § 29.1305 required indicators, the applicant needs to show equivalence. Coordinate with engine and powerplant specialists since they will need to assist in the evaluation of the monitoring algorithm parameters. Depending on the strategy employed, the engine manufacturer may also need to be involved. Additionally, coordinate early with the FAA/AUTHORITY since there will need to be an equivalent level of safety.
(ii) System displays. Display of system information (e.g., hydraulic system information, electrical system information), other than powerplant information, may be combined onto an EICAS or IIDS display or displayed on separate displays.
(A) Crew Alerting System (CAS) and Caution Advisory Warning System (CAWS). EDSs may include CAS message windows or CAS messages may display on a separate display. CAS messages must be easily seen and legible in all lighting conditions. The messages or labels must be easily understandable and use standardized acronyms or labels. Display of CAS messages should be located as close to the pilot’s central line of vision as possible unless there is a Master Caution or Master Warning indicator in the pilot’s primary field of view.
(1) Managing Messages and Prompts. The following general guidance applies to all messages and prompts:
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