V. Navigation Systems – Task A. Intercepting and Tracking Navigational Systems and DME Arcs (Operational Requirements)

Objective

The student will demonstrate comprehensive knowledge of operational requirements and limitations for intercepting and tracking navigational systems and DME arcs in helicopter instrument flight operations. Upon completion, the student will be able to:

• Explain operational requirements for selecting and using DME arc procedures (IH.XII.C.K1)
• Describe when and how RNAV substitution techniques may be used for DME arcs
• Identify equipment requirements for flying published DME arc approaches
• Explain the differences between helicopter and airplane DME arc operations
• Demonstrate understanding of charting requirements and limitations for DME arc selection during instrument flight evaluations

This ground lesson supports ACS Area of Operation XII (Navigation Systems) and prepares the student for practical application during subsequent flight lessons involving DME arc intercepts and tracking.

Content

Introduction

DME arcs represent a unique approach segment that requires precise navigation equipment and technique. Unlike fixed-wing aircraft that commonly fly DME arcs at higher speeds, helicopters flying DME arcs face distinct challenges related to lower groundspeeds, wind correction angles, and the need for continuous position awareness in single-pilot IFR operations. This lesson addresses the operational requirements and limitations that govern when and how DME arcs may be flown, with particular emphasis on equipment requirements, charting standards, and RNAV substitution provisions.

Regulatory Framework

14 CFR §91.205(d) establishes required instruments and equipment for IFR flight. For DME arc operations specifically:

• Distance measuring equipment (DME) or suitable RNAV system must be installed and operational
• Two-way radio communication equipment
• Navigation equipment suitable for the route to be flown

14 CFR §91.175(a) requires approach procedures to be conducted in accordance with published approach charts and standard instrument approach procedures approved by the Administrator.

AIM Chapter 1, Section 1-1-17 and AIM Chapter 5, Section 5-3-7 address DME operations and DME arc approach procedures.

DME Arc Operational Requirements (IH.XII.C.K1)

The ACS specifically states: “The evaluator may not select DME arcs, unless charted and available (including use of RNAV substitution techniques, if appropriate).” This requirement contains three critical operational limitations:

1. Charted Requirement

DME arcs must be published on an approved instrument approach procedure chart. This means:

• The arc must appear as a defined transition or approach segment on a current FAA chart
• The DME facility, distance, and course guidance must be explicitly depicted
• Advisory arcs or suggested routing not part of an approach procedure do NOT satisfy this requirement
• The helicopter must be authorized to fly the approach procedure containing the arc

Example: The VOR/DME-A approach at Flagstaff Pulliam Airport (KFLG) depicts a 17 DME arc from the FLG VOR. This is charted and may be selected for evaluation.

Counter-example: A controller providing vectors with instructions to “maintain 15 DME from the XYZ VOR” without reference to a published procedure does NOT constitute a charted DME arc for evaluation purposes.

2. Available Equipment

“Available” means the aircraft must have:

• Operational DME equipment displaying distance from the NAVAID, OR
• An approved RNAV system capable of DME substitution (addressed below)
• The NAVAID providing the DME arc must be operational and monitored

In helicopters certificated for IFR flight, the DME may be:

• Standalone DME unit interrogating a VORTAC or VOR/DME
• Integrated DME capability in a VOR/DME receiver
• GPS/FMS-derived DME distance when using RNAV substitution

Helicopter-Specific Consideration: Most training helicopters (Robinson R44 IFR, Schweizer 300CBi, Enstrom 280FX) have basic panel-mounted DME units. Unlike turbine helicopters with integrated flight management systems, these training aircraft require the pilot to manually monitor DME distance and make frequent heading corrections due to the absence of autopilot coupling.

3. RNAV Substitution Techniques

Per AIM 1-2-3 and AC 90-108, aircraft equipped with IFR-approved GPS or RNAV systems may substitute GPS/RNAV for ADF and DME, subject to specific conditions:

RNAV Substitution for DME Arcs is PERMITTED when:

• The aircraft has IFR-approved GPS (TSO-C129a/c146a or later)
• GPS integrity monitoring is operational (RAIM available or WAAS)
• The substitution meets AC 90-108 requirements
• The GPS database includes the DME facility as a waypoint or reference
• The pilot monitors GPS derived distance-to-facility to fly the arc

RNAV Substitution Requirements:

• GPS must provide equivalent navigation performance to the ground-based NAVAID
• Pilot must monitor GPS-derived DME distance, not relying solely on magnetic bearing
• For arc-to-radial transitions, GPS course guidance may be used
• NOTAM restrictions or approach chart notes may prohibit GPS substitution for specific procedures

Critical Limitation: Even with RNAV substitution capability, the evaluator may not select the DME arc unless it is charted. RNAV substitution addresses equipment availability, not charting requirements.

Operational Planning Considerations

Pre-flight Planning:

1. Review approach chart for DME arc segments—identify which approaches contain arcs
2. Check NOTAM for DME facility outages or GPS restrictions
3. Confirm aircraft equipment: DME operational or GPS approved for substitution
4. Calculate arc radius and approximate arc length for timing estimates
5. Determine lead radials for arc interception if transitioning from another segment

Equipment Verification:

• DME equipment test per 14 CFR §91.413 (within 24 calendar months if separate unit)
• VOR checks current per 14 CFR §91.171 (within 30 days)
• GPS database current within 28-day cycle (14 CFR §91.175(a))
• RAIM prediction accomplished if using GPS substitution

Chart Depiction Analysis:

• Identify arc radius (e.g., “17 DME ARC”)
• Note lead radials showing arc entry points
• Determine arc altitude restrictions
• Identify arc-to-final transition radial
• Check minimum altitudes throughout arc segment

Risk Management Elements

Although the ACS does not list specific risk management items for IH.XII.C (operational requirements), instructors should address these operational risks:

Situational Awareness Loss:

• Single-pilot IFR helicopter operations demand high workload during DME arc tracking
• Loss of DME signal during arc requires immediate recognition and appropriate action
• GPS failure when using RNAV substitution may occur without obvious alert

Equipment Knowledge Deficiency:

• Pilots unfamiliar with DME/GPS equipment operation may misinterpret distance information
• Confusion between DME distance (slant range) and GPS ground distance
• Failure to recognize DME station passage or distance anomalies

Regulatory Compliance:

• Flying DME arcs that are not charted constitutes a deviation from ATC clearance
• Using GPS substitution without proper authorization violates operating limitations
• Attempting arcs when required equipment is inoperative is illegal under 14 CFR §91.205

Differences from Airplane Operations

Helicopter DME arc operations differ from airplane operations in several ways:

Lower Groundspeeds:

• Helicopters typically fly arcs at 70-90 KIAS vs. 120+ KIAS for light airplanes
• Slower speeds provide more time for corrections but increase wind drift effect
• Proportionally larger wind correction angles required

Workload Concentration:

• Single-pilot helicopters lack autopilot coupling common in IFR airplanes
• Cyclic, collective, and pedal coordination required while managing navigation equipment
• Heads-down time monitoring DME must be minimized due to helicopter instability

Arc Radius Selection:

• Some approaches publish different arc radii for helicopters (e.g., closer arcs)
• Helicopter maneuverability allows tighter turns onto final approach course
• Visibility category limitations may differ (Cat A/B minima)

Practical Application Scenarios

Scenario 1: Standard DME Arc with Conventional Equipment Aircraft: Robinson R44 with King KN-62A DME, dual VOR/ILS receivers Approach: VOR/DME-A with 15 DME arc Requirements: DME operational, VOR check current, NOTAM reviewed Technique: Monitor DME distance, make 10° heading changes to maintain arc

Scenario 2: GPS Substitution for DME Arc Aircraft: Schweizer 300CBi with Garmin GTN 650 GPS/NAV/COM Approach: VOR/DME-C with 18 DME arc, DME ground facility out of service Requirements: GPS IFR-approved, RAIM available, database current, AC 90-108 compliance Technique: Use GPS-derived distance from VOR waypoint to maintain arc

Scenario 3: Evaluator Selection Limitation Situation: Practical test, helicopter equipped with DME, nearby approach has advisory arc Limitation: Evaluator may NOT select this arc because it is not charted as part of published procedure Alternative: Evaluator must select approach with charted DME arc or omit DME arc evaluation

Schedule

Equipment

Required References:

• FAA-S-ACS-14, Instrument Rating – Helicopter (current edition)
• FAA-H-8083-15B, Instrument Flying Handbook (Chapter 9 - Navigation Systems)
• FAA-H-8083-21B, Rotorcraft Flying Handbook
• AIM (Aeronautical Information Manual), current edition—specifically:
  • Chapter 1, Section 1-1-17 (Global Positioning System)
  • Chapter 1, Section 1-2-3 (Use of Suitable RNAV Systems)
  • Chapter 5, Section 5-3-7 (Instrument Approach Procedures)
• AC 90-108, Use of Suitable Area Navigation Systems on Conventional Routes and Procedures
• 14 CFR Part 91, Subpart B (Flight Rules)

Approach Charts (current, up-to-date examples):

• Minimum of three approach charts depicting DME arcs (various radii)
• One example of approach WITHOUT DME arc for comparison
• Terminal procedures publication (TPP) or electronic equivalent

Aircraft Documentation:

• Sample aircraft flight manual supplement for IFR-approved GPS
• POH/RFM equipment list showing DME or GPS installation
• Example aircraft equipment list from training helicopter

Visual Aids:

• Whiteboard or tablet for drawing DME arc geometry
• DME arc diagram showing lead radials, arc segment, and transition
• Sample GPS substitution decision flowchart
• Equipment panel photographs showing DME and GPS displays

Handouts (student retention materials):

• ACS excerpt for IH.XII.C with knowledge elements highlighted
• Summary chart: “DME Arc Operational Requirements Checklist”
• AC 90-108 GPS substitution quick reference card
• Sample pre-flight planning worksheet for DME arc approaches

Technology:

• Computer/tablet for displaying electronic charts
• Access to ForeFlight or similar EFB for NOTAM/chart demonstrations
• Projector or shared screen capability if available

Instructor Actions

1. Begin with scenario-based question: “You’re planning an IFR flight to an airport with two approaches available: one with a DME arc and one without. Your helicopter’s DME failed the pre-flight test. Can you still request and fly the DME arc approach? Why or why not?” Allow student to reason through the problem, then connect to lesson objectives.

2. Establish the regulatory foundation: Present 14 CFR §91.205(d) and explain that DME is required IFR equipment only when specifically required for the route or approach. State: “DME becomes required equipment when you choose an approach or route that specifies DME—that’s the regulatory basis for today’s operational requirements discussion.”

3. Introduce the ACS standard IH.XII.C.K1: Read the exact ACS language: “The evaluator may not select DME arcs, unless charted and available (including use of RNAV substitution techniques, if appropriate).” Emphasize three key terms: CHARTED, AVAILABLE, and RNAV SUBSTITUTION.

4. Define and demonstrate “charted” requirement: Display approach chart with published DME arc. Point to arc depiction, radius notation, and lead radials. State: “This is charted—it’s part of the published procedure approved by the FAA.” Then show approach chart without arc or display en route chart with advisory DME reference. State: “These are NOT charted DME arcs for evaluation purposes.”

5. Explain why charting matters: “The ACS prevents evaluators from creating their own DME arc scenarios. This ensures standardization—every applicant is evaluated on published procedures, not made-up arcs. It also ensures you’re flying procedures with verified obstacle clearance and approved minima.”

6. Use analogy for clarity: “Think of it like reading sheet music versus improvising. You can’t improvise a DME arc and call it an instrument approach—it must be written in the music, which is the published chart.”

7. Address equipment availability: Display aircraft panel or POH equipment list showing DME installation. Explain operational test requirements per 14 CFR §91.413 (24-month inspection interval for transponders and DME). State: “Available means installed, operational, and legal for IFR use—not just physically present in the panel.”

8. Demonstrate pre-flight equipment verification: Walk through actual DME self-test procedure: “During pre-flight, you’ll turn on the DME, tune a nearby VOR/DME, and verify reasonable distance indication. If it shows wildly incorrect distance or ‘dashes,’ it’s not available.”

9. Introduce RNAV substitution with clear framework: “Now, what if your DME fails but you have IFR-approved GPS? AC 90-108 is your authorization to substitute GPS for DME—but there are specific rules.” Present AC 90-108 decision tree or flowchart.

10. Detail GPS substitution requirements: List on whiteboard: “(1) GPS must be IFR-approved (TSO-C129/C146 or better), (2) RAIM or WAAS available, (3) database current within 28 days, (4) no NOTAM prohibitions, (5) pilot monitors GPS-derived distance.” Work through each requirement with student.

11. Clarify GPS database currency: “14 CFR §91.175(a) requires current database for GPS approaches. While technically you might fly a DME arc substitution with expired database under certain conditions, best practice is current database—period. This eliminates any question during a checkride.”

12. Address GPS-derived DME vs. conventional DME: Explain slant range consideration: “Conventional DME shows slant range distance—the straight-line distance to the station, including altitude component. GPS typically shows ground distance to the lat/long position of the station. At typical DME arc radii (10-20 DME), this difference is negligible, but you need to understand your equipment.” Use diagram showing altitude triangle to illustrate.

13. Demonstrate chart analysis technique: Take approach chart with DME arc and systematically identify: “(1) Arc radius—18 DME; (2) Lead radials showing entry points—here and here; (3) Arc altitude—2,800 MSL; (4) Arc-to-final transition—intercept 113° radial; (5) Missed approach point reference—if applicable.” Model this process aloud so student learns analytical sequence.

14. Explain operational planning sequence: “Before you launch on an IFR flight where you might fly a DME arc, here’s your preflight checklist: check NOTAM for DME facility status; verify your aircraft DME operational or GPS legal for substitution; confirm approach chart currency; brief the arc entry, tracking, and transition; calculate approximate time on arc based on your groundspeed.”

15. Present risk management scenarios: Describe situation: “You’re established on the 15 DME arc, tracking nicely, when suddenly your DME display goes blank. What do you do?” Facilitate discussion: notify ATC immediately, request vectors or alternate approach, do not continue arc without distance reference.

16. Address single-pilot workload consideration: “In a helicopter without autopilot, you’re hand-flying while monitoring DME, making heading corrections, communicating with ATC, and preparing for the next segment. This is significantly higher workload than coupled autopilot systems in larger aircraft. Divide your scan: outside-instruments-DME-outside, spending no more than 2-3 seconds heads-down on any single instrument.”

17. Compare helicopter vs. airplane DME arc operations: Draw comparison table: “Helicopter groundspeed: 80 knots; small airplane: 120 knots. For the same 30-knot crosswind, the helicopter needs a wind correction angle 1.5 times larger. But you also have more time to see drift and correct. It’s a tradeoff—use that extra time wisely.”

18. Illustrate practical scenario with equipment failure: “You’re flying a Robinson R44 with a single DME unit. At 5 DME on the arc, the DME fails—just shows dashes. You have no GPS. This is equipment failure requiring immediate action. What’s the procedure?” Lead student to: inform ATC, unable to continue arc, request radar vectors or different approach.

19. Present GPS substitution scenario: “Same situation, but you have a Garmin GTN 750 with current database and RAIM. Your DME fails. Can you continue? Yes—you’re authorized under AC 90-108 to use GPS-derived distance. How do you do this?” Demonstrate on GPS simulator or photo: tune VOR as waypoint, display distance-to-waypoint, monitor that distance instead of DME.

20. Clarify evaluator limitations during practical test: “Here’s a critical point: during your instrument checkride, the examiner can only ask you to fly DME arcs that are charted. If you show up to a test location where no published approaches have DME arcs, the examiner must skip that task. The ACS prevents examiners from saying, ‘Maintain 10 miles from that VOR’—that’s not a charted procedure.”

21. Address common misconception: “Some pilots think that having GPS automatically qualifies every approach as a ‘GPS approach.’ That’s wrong. GPS substitution under AC 90-108 lets you use GPS to navigate a VOR/DME approach, but you’re still flying the VOR/DME procedure with its minima, not a GPS approach.”

22. Explain NOTAM checking requirement: “Before flight, check NOTAM for both DME facility status and any GPS restrictions. Some approaches have ‘GPS unusable’ NOTAM due to military testing or interference. If GPS is NOTAM’d unusable and you’re relying on GPS substitution for DME, you can’t fly that arc legally.”

23. Use teaching analogy for RNAV substitution: “Think of RNAV substitution like using your smartphone calculator instead of a physical calculator. Both give you the answer, but they must both be approved tools. Your smartphone is approved (GPS IFR certification), and the math problem is fair game (charted DME arc), so you’re good to go.”

24. Demonstrate chart notation interpretation: Point to approach chart notes section. “Look here—some charts say ‘DME required’ or ‘RADAR required.’ These notes tell you equipment requirements. If it says ‘DME required’ and you have GPS substitution capability, you’re legal—AC 90-108 allows substitution. But if it says ‘GPS’ specifically in the procedure title, different rules apply.”

25. Facilitate student practice with chart identification: Provide three approach charts. Ask student to identify which one(s) have charted DME arcs available for checkride evaluation. Have student explain their reasoning for each chart: “Walk me through your analysis—is there a DME arc? Is it charted as part of the procedure?”

26. Address altitude consideration during arc: “DME is slant range, remember. When you’re at 3,000 feet AGL, flying a 15 DME arc, you’re not 15 nautical miles horizontally from the station—you’re about half a mile closer in ground distance. At typical arc radii and altitudes, this error is small, but understand the geometry.”

27. Review equipment certification requirements: “For GPS to be legal for IFR substitution, it must be installed per IFR installation standards and have appropriate TSO certification. Panel-mount GPS with IFR approval: yes. Portable GPS like handheld Garmin, even with WAAS: no. The regulation requires installed, certified equipment.”

28. Present decision-making framework: Create decision tree on board: “Step 1: Is DME arc charted? If NO—not available for evaluation. If YES—proceed. Step 2: Is DME equipment operational? If YES—qualified. If NO—proceed. Step 3: Is IFR GPS available and legal for substitution? If YES—qualified. If NO—not available.”

29. Discuss scenario planning for practical test: “When you schedule your checkride, look at approaches available at the test airport. If no DME arcs exist within reasonable diversion distance, discuss with examiner beforehand. They may need to adjust test location or plan to skip that task—it’s the examiner’s responsibility to select appropriate tasks per ACS.”

30. Conclude with comprehensive review question: “Let me give you a complex scenario: You’re flying a helicopter with inoperative DME but operational IFR GPS. You want to fly an approach with a 12 DME arc. The approach chart shows the arc clearly, but there’s a NOTAM: ‘GPS unreliable within 5 NM of XYZ VOR.’ Can you fly this approach? Why or why not?” Facilitate discussion covering charted (yes), DME available (no), GPS substitution (NOTAM restricts), conclusion (not available).

Student Actions

1. Actively engage with opening scenario: Respond to instructor’s equipment failure question, articulate initial reasoning, and identify knowledge gaps that the lesson will address.

2. Take structured notes: Organize notes using the three key terms from ACS standard: CHARTED, AVAILABLE, and RNAV SUBSTITUTION as section headings.

3. Ask clarifying questions: Immediately seek clarification when instructor presents regulatory references or technical terms that are unfamiliar.

4. Examine approach charts provided: Physically handle charts or view electronic charts, locating DME arc depictions, radius notations, and lead radials while instructor explains.

5. Participate in “charted vs. not charted” discrimination exercise: When instructor presents various chart examples, verbally identify whether each contains a charted DME arc eligible for checkride evaluation.

6. Verbalize understanding of equipment requirements: Restate in own words the requirements for DME to be considered “available,” including operational status and regulatory inspection requirements.

7. Follow along with DME self-test demonstration: If instructor demonstrates equipment operation on panel photo or aircraft, mentally rehearse the sequence and ask questions about any unclear steps.

8. Document GPS substitution requirements: Create personal checklist of five AC 90-108 requirements for GPS substitution, using instructor’s presentation as source material.

9. Compare and contrast DME vs. GPS distance: Explain back to instructor the difference between slant-range DME and GPS ground distance, using altitude triangle diagram as reference.

10. Practice chart analysis systematically: When given approach chart by instructor, work through the five-step analysis process independently: identify radius, lead radials, altitude, transition, and missed approach references.

11. Develop pre-flight planning checklist: Create personal checklist for DME arc flight planning incorporating NOTAM checks, equipment verification, chart review, and briefing items.

12. Respond to risk management scenarios: When instructor presents equipment failure scenario, immediately articulate appropriate actions: notify ATC, request alternate approach, do not continue without distance reference.

13. Discuss workload management strategies: Share personal techniques or ask instructor for recommendations on managing scan patterns during single-pilot DME arc operations in helicopters.

14. Analyze helicopter-specific challenges: Contribute to discussion of wind correction angles, groundspeed effects, and workload differences between helicopter and airplane arc operations.

15. Work through equipment failure scenario: When presented with mid-arc DME failure, verbalize decision-making process: assess available equipment, determine legal options, communicate with ATC, execute alternate plan.

16. Demonstrate GPS substitution decision-making: In scenario with failed DME but operational GPS, explain authorization under AC 90-108, identify equipment requirements met, and describe technique for using GPS-derived distance.

17. Explain evaluator limitations: Articulate why ACS standard prevents examiners from selecting non-charted DME arcs, demonstrating understanding of standardization and safety rationale.

18. Correct common misconceptions: When instructor addresses GPS approach vs. GPS substitution misconception, acknowledge understanding and explain difference in own words.

19. Practice NOTAM interpretation: Review sample NOTAM provided by instructor, identify implications for DME arc operations, and determine whether GPS substitution remains viable.

20. Apply analogy to technical concept: Connect instructor’s RNAV substitution analogy (smartphone calculator) to regulatory concept, demonstrating comprehension through comparison.

21. Interpret chart notations: Examine approach chart notes section, locate equipment requirements, and determine whether GPS substitution satisfies noted DME requirements.

22. Complete chart identification exercise: Analyze three approach charts provided, identify DME arcs, and explain reasoning for each determination: charted or not charted, available or not available.

23. Consider altitude effects on DME: Calculate or conceptually understand slant-range error at typical arc altitudes and radii, recognizing when error becomes operationally significant.

24. Verify equipment certification understanding: Distinguish between IFR-approved installed GPS and non-approved portable GPS, explaining legal basis for difference.

25. Apply decision-making framework: Use instructor’s decision tree to analyze new scenario: charted? → equipment operational? → GPS available? → determine availability for evaluation.

26. Plan for practical test considerations: Identify approaches at likely checkride locations, determine DME arc availability, and discuss potential alternatives with instructor if none exist.

27. Solve comprehensive scenario: Work through instructor’s complex scenario involving inoperative DME, operational GPS, charted arc, and GPS NOTAM restriction. Systematically evaluate each factor and reach correct conclusion: not available due to NOTAM.

28. Self-assess knowledge gaps: Identify any remaining areas of uncertainty and formulate specific questions for instructor clarification.

29. Summarize key learning points: Articulate the three critical components of IH.XII.C.K1 in own words: charted requirement, equipment availability, RNAV substitution provisions.

30. Preview practical application: Ask questions about how this knowledge will be applied during flight training, particularly during upcoming lessons on DME arc interception and tracking techniques.

Completion Standards

The lesson is complete when the student demonstrates mastery of ACS task IH.XII.C operational requirements by meeting the following standards:

1. Accurately defines “charted” DME arc: Student explains that a charted DME arc is one published on an FAA-approved instrument approach procedure chart, not an advisory arc or controller instruction, and can correctly identify charted arcs on sample approach plates with 100% accuracy.

2. Explains ACS evaluator limitation: Student articulates that per ACS standard IH.XII.C.K1, an evaluator may not select DME arcs unless they are charted and available, demonstrating understanding of checkride standardization requirements.

3. Lists equipment availability requirements: Student identifies that DME equipment must be installed, operational, and meet 14 CFR §91.413 inspection requirements (24-month interval for standalone DME units), or that approved RNAV equipment is available for substitution.

4. Recites GPS substitution requirements: Student correctly states all five AC 90-108 requirements for RNAV substitution: (1) IFR-approved GPS (TSO-C129/146 or equivalent), (2) RAIM or WAAS available, (3) current database within 28-day cycle, (4) no NOTAM prohibitions, (5) pilot monitors GPS-derived distance to facility.

5. Distinguishes between DME types: Student explains the difference between slant-range DME distance and GPS ground distance, acknowledging that at typical arc radii the difference is operationally negligible but conceptually important.

6. Demonstrates chart analysis proficiency: Given an unfamiliar approach chart with DME arc, student systematically identifies: arc radius, lead radials, arc altitude restrictions, arc-to-final transition radial, and any equipment notes—completing analysis within 3 minutes with no omissions.

7. Develops compliant pre-flight plan: Student creates pre-flight planning checklist for DME arc flight that includes: NOTAM review for DME facility and GPS restrictions, equipment verification, chart currency check, arc briefing items, and time/fuel estimates.

8. Applies decision-making framework: When presented with novel scenario involving equipment status and chart availability, student systematically evaluates whether DME arc is available for flight or evaluation, reaching correct conclusion and providing sound justification.

9. Identifies risk management actions: Student describes appropriate actions for equipment failure during DME arc: immediate ATC notification, inability to continue arc navigation, request for radar vectors or alternate approach without DME requirement.

10. Explains helicopter-specific considerations: Student articulates differences between helicopter and airplane DME arc operations, including lower groundspeeds, proportionally larger wind correction requirements, higher single-pilot workload, and absence of autopilot coupling in typical training helicopters.

11. Interprets NOTAM implications: Given sample NOTAM restricting DME facility or GPS operations, student determines impact on planned DME arc flight and identifies whether GPS substitution remains authorized.

12. Distinguishes GPS substitution from GPS approach: Student correctly explains that using GPS substitution under AC 90-108 means flying a VOR/DME approach with GPS-derived navigation, not converting it to a GPS approach, and must fly published VOR/DME minima.

13. Verifies equipment certification knowledge: Student identifies that GPS equipment must be panel-mounted and IFR-approved per TSO standards, not portable/handheld equipment, for legal RNAV substitution on IFR flights.

14. Passes oral knowledge assessment: Student correctly answers minimum 9 of 10 scenario-based questions covering charting requirements, equipment availability, RNAV substitution provisions, and operational limitations without reference to notes.

15. Demonstrates practical test readiness: Student explains how to verify DME arc availability at checkride location, what to discuss with examiner if no charted arcs exist, and how to demonstrate knowledge of operational requirements even if arc flight is not evaluated.

Assessment Method: Instructor evaluates student through combination of oral questioning, chart analysis exercises, scenario-based problem-solving, and student-created planning materials. Student must meet all 15 completion standards before progressing to flight lessons involving DME arc interception and tracking.

ACS Alignment: This ground lesson satisfies the knowledge requirements of ACS task IH.XII.C.K1 regarding operational requirements and limitations for DME arc selection. While the ACS does not specify risk management or skill elements for this particular task code (operational requirements only), the completion standards ensure comprehensive understanding necessary for safe and legal DME arc operations in helicopters under instrument flight rules.

Remedial Training: If student does not meet completion standards, instructor will identify specific knowledge gaps, provide additional explanation or alternative teaching methods, assign supplementary reading (AC 90-108, AIM 1-2-3, relevant Instrument Flying Handbook sections), and re-assess before proceeding to DME arc flight training.