Cessna 172S Steam IFR Equipment & Systems — Instrument Rating Oral Questions

DPE oral questions · ifr equipment & systems

21 questions a DPE may ask in this section

1. Question 1 · IR.I.F.K1

   What are the effects on the pitot-static instruments when the static port becomes blocked (clogged)?

   What a DPE expects to hear

   • Altimeter: freezes at the altitude where the port blocked; no longer changes with actual altitude
   • VSI: immediately shows zero and stays at zero (no static pressure differential)
   • Airspeed Indicator: becomes unreliable — may over-read during descent (trapped static pressure is higher than outside), under-read during climb; may read correctly in level flight at the same altitude
   • Remedy: alternate static source (slightly higher pressure than outside — small corrections required); or break the VSI glass as a last resort to use cabin air pressure

   Common wrong answers

   • Thinking the ASI goes to zero when static port blocks (wrong — it becomes unreliable, not zero)
   • Not knowing VSI shows zero immediately
   • Not knowing altimeter freezes at blockage altitude

   SourceFAA-H-8083-16B Chapter 7; PilotsCafe IFR Quick-Review p.11

2. Question 2 · IR.I.F.K1

   What are the effects of a blocked pitot tube (with static port open)?

   What a DPE expects to hear

   • Airspeed Indicator: if static port is open but pitot tube is blocked, ASI reads zero in level flight (no ram air differential)
   • If pitot tube is blocked AND pitot drain hole is also blocked: ASI may over-read during climb (water sealed in tube expands with altitude change like an altimeter) or behave erratically
   • Altimeter: NOT affected — uses static only
   • VSI: NOT affected — uses static only
   • Pitot heat: prevents ice blockage of pitot tube; does NOT heat the static port

   Common wrong answers

   • Confusing pitot blockage with static blockage effects
   • Thinking pitot heat also heats the static port (it does not)
   • Not knowing the dual-blocked pitot/drain scenario — ASI acts like an altimeter

   SourceFAA-H-8083-16B Chapter 7; PilotsCafe IFR Quick-Review p.11

3. Question 3 · IR.I.F.K1

   What are the magnetic compass errors (DV MONA)?

   What a DPE expects to hear

   • D — Deviation: compass card deflected by aircraft magnetic fields; corrected by compass correction card in cockpit
   • V — Variation: difference between magnetic and true north; corrected by adding/subtracting variation (East is least, West is best)
   • M — Magnetic dip (Oscillation): compass bobs and weaves due to dip at low latitudes
   • O — Oscillation: erratic swings due to turbulence or uncoordinated flight
   • N — Northerly Turning Error (UNOS): In Northern hemisphere, compass leads during a turn from North, lags from South — UNOS: Undershoot North, Overshoot South
   • A — Acceleration Error (ANDS): acceleration = North indication; deceleration = South indication — ANDS: Accelerate North, Decelerate South
   • Most reliable: wings-level, constant speed, coordinated flight on an E/W heading

   Common wrong answers

   • Confusing ANDS and UNOS
   • Not knowing compass is most reliable on E/W headings
   • Forgetting deviation is a correctable, charted error

   SourceFAA-H-8083-16B Chapter 7; PilotsCafe IFR Quick-Review p.12

4. Question 4 · IR.I.F.K1

   What is RAIM and how does it affect your GPS approach?

   What a DPE expects to hear

   • RAIM = Receiver Autonomous Integrity Monitoring; the GPS receiver's self-checking system to verify satellite geometry is adequate for navigation
   • For enroute GPS: requires 5 satellites for RAIM; for approach: requires 6 satellites (or 5 + barometric altimeter input)
   • If RAIM is not available, the GPS cannot be used as a primary navigation source for IFR
   • Check RAIM availability before flight for approaches (www.faa.gov/air_traffic/flight_info/aeronav/acrobat/RAIM_prediction.pdf or apps/avionics)
   • WAAS-equipped aircraft: WAAS replaces RAIM with a more robust integrity system — FDE (Fault Detection and Exclusion)
   • Non-WAAS GPS: MUST predict RAIM availability for approach phase, especially at remote airports

   Common wrong answers

   • Thinking WAAS GPS still requires traditional RAIM prediction (WAAS uses FDE instead)
   • Not knowing the 6-satellite requirement for approach phase
   • Confusing RAIM with GPS database currency

   SourceAIM 1-1-17; PilotsCafe IFR Quick-Review p.8

5. Question 5 · IR.I.F.K1

   What is the difference between WAAS and non-WAAS GPS? What approach minimums does each support?

   What a DPE expects to hear

   • Non-WAAS (TSO-C129): provides lateral navigation; supports LNAV approaches with MDA; accuracy ~100 meters
   • WAAS (TSO-C145/146): Wide Area Augmentation System; provides both lateral AND vertical guidance; supports LPV, LNAV/VNAV, LNAV approaches; accuracy <3 meters
   • WAAS uses ground reference stations and a geostationary satellite to correct GPS errors in real time
   • LPV approaches (only with WAAS): glidepath guidance with precision-approach-like minimums (as low as 200 ft DA / 2400 RVR)
   • LNAV/VNAV: available with WAAS OR baro-VNAV; vertical guidance to MDA on the glidepath
   • Under ACS-8C: LPV satisfies the precision approach requirement

   Common wrong answers

   • Thinking non-WAAS GPS can fly LPV approaches
   • Not knowing WAAS replaces RAIM prediction need
   • Confusing LNAV/VNAV (available without WAAS with baro input) with LPV (WAAS only)

   SourceAIM 1-1-18; FAA-S-ACS-8C; PilotsCafe IFR Quick-Review p.8, 16

6. Question 6 · IR.I.F.K1

   What are the spatial disorientation illusions most likely to affect IFR pilots? Name at least five.

   What a DPE expects to hear

   • The Leans: only the vestibular system (semicircular canals), not visual — sudden level after prolonged bank causes sensation of banking opposite way; pilot leans to feel 'level'
   • Graveyard Spiral: sustained turn → semicircular canal fluid stops → feels level; correction returns roll sensation; pilot pushes forward to stop 'climb'
   • Somatogravic Illusion: rapid acceleration feels like nose-up pitch; pilot pushes forward into ground
   • Somatogyral Illusion: prolonged roll → fluid stops → feel upright; reversal feels like rotation opposite direction
   • Inversion Illusion: abrupt level-off from climb feels like tumbling backward
   • Elevator Illusion: updraft causes impression of climbing; pilot pushes forward
   • The Leans is the most common spatial disorientation in IFR

   Common wrong answers

   • Confusing the Leans with the Graveyard Spiral
   • Not knowing the Somatogravic illusion affects acceleration on takeoff (pushes forward into ground)
   • Thinking VFR visibility alone prevents spatial disorientation

   SourceFAA-H-8083-25C Chapter 17; PilotsCafe IFR Quick-Review p.25–27

7. Question 7 · IR.I.F.K1

   What is hypoxia and how does it affect an IFR pilot at altitude?

   What a DPE expects to hear

   • Hypoxia = insufficient oxygen supply to the brain; impairs judgment, reasoning, memory, and motor control
   • Insidious because the pilot typically feels fine and may feel euphoric — no pain, minimal warning
   • Onset: at 10,000 feet, night vision impaired; at 14,000 feet, performance significantly impaired; at 18,000 feet, incapacitation in ~30 minutes
   • IFR ops: §91.211 requires supplemental oxygen above 12,500 feet MSL for flights >30 minutes; above 14,000 feet at all times; above 15,000 feet for passengers at all times
   • Treatment: descend and use supplemental oxygen immediately upon recognition

   Common wrong answers

   • Thinking hypoxia causes obvious symptoms (it typically does not)
   • Confusing the altitude thresholds for oxygen requirements
   • Not knowing night vision is first to be impaired at altitude

   Source14 CFR §91.211; PHAK Chapter 17; PilotsCafe IFR Quick-Review p.25

8. Question 8 · IR.I.F.K1

   On your pre-takeoff check, you find the pitot heat is inoperative. The forecast route is in clouds with temperatures between -2°C and +5°C — prime icing range. How does this affect your flight?

   What a DPE expects to hear

   • Pitot heat is NOT listed in §91.205(d) (GRAB CARD). Pitot-heat operability for IFR in icing is governed by the AFM/POH operating limitations (enforced via §91.9) and §91.213 (inoperative equipment). If the POH lists pitot heat as required for IFR, its failure renders the aircraft not airworthy under §91.213.
   • Without pitot heat, airspeed indicator is susceptible to icing in visible moisture at near-freezing temps
   • This is a go/no-go decision: if the flight will be in icing conditions (visible moisture + temp at or below 0°C), flying without functional pitot heat is unsafe
   • Per §91.213: if pitot heat is a required item on the MEL or required by §91.205, it cannot be deferred for IFR in icing conditions
   • Correct action: do not depart IFR in forecast icing without functional pitot heat

   Common wrong answers

   • Thinking pitot heat is optional because the aircraft has a working ASI
   • Not knowing pitot heat is specifically required for IFR under §91.205
   • Thinking 'minimum fuel, max range' solves the problem

   Source14 CFR §91.205(d); §91.213; PilotsCafe IFR Quick-Review p.12

9. Question 9 · IR.I.F.K1

   Explain the difference between the three levels of GPS sensitivity during an RNAV approach. When does each occur and why does it matter?

   What a DPE expects to hear

   • Enroute sensitivity: ±5.0 NM full-scale deflection; used during cruise flight
   • Terminal sensitivity: ±1.0 NM; activates within 30 NM of destination or when selected terminal mode
   • Approach sensitivity: ±0.3 NM (LNAV); activates 2 NM before FAF when approach mode is armed
   • LPV approach: additional angular sensitivity (like an ILS) activates on final — narrows from 0.3 NM to ±350 feet at threshold
   • Why it matters: if sensitivity doesn't switch to approach mode, you're flying with 1.0 NM CDI deflection on final — huge error. Must verify 'LNAV' or 'LPV' is annunciated before FAF.
   • Practical: if GPS doesn't sequence to approach mode, execute missed approach or request alternate approach

   Common wrong answers

   • Not knowing sensitivity changes automatically at specific triggers
   • Not verifying the GPS is in approach mode before the FAF
   • Thinking full-scale deflection is the same for all modes

   SourceAIM 1-1-18; FAA-H-8083-16B; PilotsCafe IFR Quick-Review p.16

10. Question 10 · IR.II.A.K1

    What does the IFR equipment acronym GRAB CARD stand for, and what regulation requires it?

    What a DPE expects to hear

    • G — Generator/alternator
    • R — Radio: communications appropriate to route
    • A — Altimeter (sensitive)
    • B — Ball (inclinometer/slip-skid indicator)
    • C — Clock (or approved elapsed timer)
    • A — Attitude indicator
    • R — Rate-of-turn indicator (TC or turn-and-bank)
    • D — Directional gyro (heading indicator)
    • Required by 14 CFR §91.205(d) for IFR flight

    Common wrong answers

    • Forgetting the generator/alternator requirement
    • Listing DME or transponder as mandatory for all IFR (they are altitude-specific or Class A)
    • Confusing GRAB CARD with VFR day (ATOMATOFLAMES) equipment

    Source14 CFR §91.205(d)

11. Question 11 · IR.II.A.K2

    Explain the pitot-static system. What three instruments use it and how does a blocked pitot tube affect each?

    What a DPE expects to hear

    • Pitot tube measures impact (ram) air pressure; static port measures ambient atmospheric pressure
    • Instruments: Airspeed Indicator (pitot + static), Altimeter (static only), VSI (static only)
    • Blocked pitot tube (with drain hole open): ASI reads zero — no ram air entering
    • Blocked pitot tube (drain hole also blocked): ASI acts like altimeter — reads high if climbing, low if descending (pressure trapped)
    • Altimeter and VSI unaffected by pitot blockage — they use static only
    • Solution: pitot heat to melt ice blockage

    Common wrong answers

    • Thinking altimeter fails when pitot is blocked
    • Not knowing about the drain hole distinction for pitot blockage behavior
    • Confusing pitot blockage with static blockage

    SourceFAA-H-8083-15B (IFH) Chapter 5; PilotsCafe IFR Quick-Review p.11

12. Question 12 · IR.II.A.K2

    What happens to the altimeter, VSI, and airspeed indicator when the static port is completely blocked?

    What a DPE expects to hear

    • Altimeter: freezes at the altitude where blockage occurred — will not change even if you climb or descend
    • VSI: reads zero — no pressure differential can develop
    • ASI: may over-read or under-read depending on altitude change; reads higher than actual if you descend (static pressure trapped is lower than ambient), lower than actual if you climb
    • Alternate static source (if available): opens to cabin air — typically slightly lower pressure than outside, causing altimeter to read slightly high, ASI to read slightly fast, VSI to show brief momentary climb
    • Emergency: break the VSI glass — connects static system to cabin air

    Common wrong answers

    • Thinking static blockage only affects the altimeter
    • Not knowing about alternate static source pressure effects
    • Forgetting the VSI glass break option

    SourceFAA-H-8083-15B (IFH) Chapter 5; PilotsCafe IFR Quick-Review p.11

13. Question 13 · IR.II.A.K2

    Describe the magnetic compass errors summarized by DV MONA.

    What a DPE expects to hear

    • D — Deviation: error caused by aircraft magnetic fields; corrected by compass swing (correction card in cockpit)
    • V — Variation: angular difference between true north and magnetic north; corrected using isogonic lines
    • M — Magnetic dip: compass card tilts toward closer magnetic pole; source of turning and acceleration errors
    • O — Oscillation: compass swings and is difficult to read in turbulence
    • N — Northerly turning error: in the northern hemisphere, compass LAGS when turning from north, LEADS when turning from south (Stop early when turning to north, overshoot to south)
    • A — Acceleration error: ANDS — Accelerate=North, Decelerate=South (in northern hemisphere, on east/west headings)

    Common wrong answers

    • Saying the compass leads when turning through north (it lags)
    • Forgetting that turning errors are worst near north and south headings
    • Not knowing ANDS mnemonic for acceleration error direction

    SourceFAA-H-8083-15B (IFH) Chapter 5; PilotsCafe IFR Quick-Review p.12

14. Question 14 · IR.II.A.K3

    What is RAIM and why does it matter for IFR GPS approaches?

    What a DPE expects to hear

    • RAIM = Receiver Autonomous Integrity Monitoring
    • GPS receiver self-monitors integrity of the satellite signal: determines if the position solution is trustworthy
    • Requires at least 5 satellites for detection; 6 for fault exclusion (FDE)
    • Must check RAIM availability before an IFR GPS approach — if RAIM is unavailable at ETA, approach is not authorized
    • RAIM prediction available via: Garmin RAIM prediction tool, ForeFlight, FAA SAPT, NOTAMs (GPS advisory)
    • If RAIM fails during an approach: missed approach immediately — navigation may not be reliable
    • WAAS GPS does not rely on RAIM in the same way — SBAS provides external integrity monitoring

    Common wrong answers

    • Thinking WAAS also uses RAIM (WAAS uses SBAS/external integrity instead)
    • Not checking RAIM before an IFR GPS approach
    • Not knowing the satellite counts for detection vs. fault exclusion

    SourceAIM 1-1-17; FAA-H-8083-15B (IFH) Chapter 2

15. Question 15 · IR.II.A.K3

    What is the difference between WAAS and non-WAAS GPS for IFR approaches?

    What a DPE expects to hear

    • Non-WAAS GPS: authorized for RNAV (GPS) approaches to LNAV and LP minimums only; uses RAIM for integrity
    • WAAS GPS: uses SBAS (Satellite Based Augmentation System) ground stations to correct for ionospheric delay and improve accuracy; authorized for LNAV, LNAV/VNAV, LPV, and LP minimums
    • LPV (Localizer Performance with Vertical guidance): WAAS-only; DA as low as 200 ft / 1/2 SM; satisfies precision approach task on ACS (FAA-S-ACS-8C change)
    • WAAS provides both lateral and vertical guidance with ILS-like accuracy on LPV approaches
    • Key planning difference: non-WAAS GPS — destination OR alternate must have conventional approach

    Common wrong answers

    • Thinking non-WAAS GPS can fly LPV approaches
    • Believing any RNAV approach can be used as a precision approach without WAAS
    • Confusing WAAS accuracy with ILS accuracy on all approaches (only LPV compares to ILS)

    SourceAIM 1-1-18; FAA-S-ACS-8C; PilotsCafe IFR Quick-Review p.13

16. Question 16 · IR.II.A.K1

    What are the VOR receiver check requirements for IFR flight under §91.171?

    What a DPE expects to hear

    • VOR must be checked within 30 days preceding the IFR flight
    • Methods and tolerances (mnemonic DEPS): VOT (±4°), Ground checkpoint (±4°), Airborne checkpoint (±6°), Dual VOR check (±4° between receivers)
    • Required logbook entry: Date, Place, Bearing error, Signature of PIC
    • VOT: tune the VOT frequency; correct indication is 0° TO (or 180° FROM). Must be within ±4°
    • Ground checkpoint: fly over a specific ground point published in the A/FD; check indicated bearing matches published bearing
    • If no VOT or ground checkpoint available, may select own prominent ground point and fly over it

    Common wrong answers

    • Thinking a 30-day check is optional for IFR
    • Not knowing the ±4° vs ±6° distinction by method
    • Forgetting all 4 elements of the logbook entry (DEPS)

    Source14 CFR §91.171; PilotsCafe IFR Quick-Review p.5

17. Question 17 · IR.II.A.K1

    What is the IFR equipment required by §91.205(d)? Use GRAB CARD.

    What a DPE expects to hear

    • G — Generator or alternator (electrical power source)
    • R — Radio: 2-way radio communication AND navigation equipment appropriate to the route
    • A — Altimeter (adjustable/sensitive barometric altimeter)
    • B — Ball (inclinometer — the slip-skid indicator, part of the turn coordinator or separate)
    • C — Clock (or approved timing device with hours, minutes, seconds — stopwatch acceptable)
    • A — Attitude indicator (gyroscopic)
    • R — Rate-of-turn indicator (gyroscopic — TC or turn-and-bank indicator)
    • D — Directional gyro (heading indicator)
    • Plus VFR day equipment (§91.205(b)) plus VFR night equipment if night IFR

    Common wrong answers

    • Listing GPS as required equipment (it is not required unless flying GPS-dependent routes)
    • Forgetting the generator/alternator
    • Not knowing a clock is explicitly required

    Source14 CFR §91.205(d); PilotsCafe IFR Quick-Review p.12

18. Question 18 · IR.II.A.K2

    Your GPS database expired 5 days ago. Can you use your GPS for IFR navigation? Can you fly an IFR GPS approach?

    What a DPE expects to hear

    • Expired database — navigation: per AIM 1-1-17, you CAN use GPS for IFR en-route navigation with an expired database IF you verify that the navigation points (waypoints, airways) being used are still valid and unchanged against current FAA data
    • Expired database — approaches: CANNOT fly an instrument approach procedure (RNAV/GPS approach) with an expired database — AIM 1-1-17 explicitly prohibits this
    • Reason: approach databases are safety-critical; a changed waypoint or minimums on an approach could cause CFIT
    • Practical implication: with expired database, GPS can only be used for supplemental navigation along published airways that you verify are unchanged
    • Best practice: always update database before IFR flight; expired database creates significant operational limitations
    • Reference: AIM 1-1-17 (a)(1) — database currency requirement

    Common wrong answers

    • Thinking expired database prevents all GPS use
    • Thinking an updated tablet database covers the approach prohibition for the panel GPS
    • Not knowing approaches are specifically prohibited with expired database

    SourceAIM 1-1-17; PilotsCafe IFR Quick-Review p.12-13

19. Question 19 · IR.II.A.K2

    What is the difference between a primary and supporting instrument in instrument flight?

    What a DPE expects to hear

    • Primary instrument: the instrument that gives the most direct indication of the parameter being controlled at a given moment
    • Supporting instruments: provide backup and trend information — confirm what the primary shows
    • For attitude: when maintaining straight-and-level, the AI (attitude indicator) is primary for pitch and bank
    • For altitude: during level flight, the ALTIMETER is primary for altitude; VSI is supporting
    • For heading: the DI (directional gyro / HSI) is primary for heading during straight flight
    • During instrument scan, primary instruments change depending on the phase of flight — e.g., during a turn, TC becomes primary for bank
    • The importance: if primary fails, the student must shift to supporting — partial panel is essentially losing a primary

    Common wrong answers

    • Thinking the AI is always primary (it changes by phase of flight)
    • Confusing primary-supporting with primary-secondary (different instrument categories)
    • Not knowing which instruments become primary on partial panel

    SourceFAA-H-8083-15B (IFH) Chapter 6

20. Question 20 · IR.II.A.K1

    What is the pitot heat requirement for IFR flight?

    What a DPE expects to hear

    • §91.205(d) requires IFR equipment — this includes the ASI which depends on pitot
    • No specific FAR mandates pitot heat be FUNCTIONAL for IFR, but if pitot heat is required by the POH for flight into known or potential icing conditions: it must be operable
    • If pitot heat is listed on the aircraft's MEL or KOEL as required for IFR: it must work
    • Practical: for most training aircraft, pitot heat is a strong recommendation — its inoperability with icing forecast could make the aircraft unairworthy for IFR in icing conditions
    • §91.213: inoperative equipment must be assessed — if pitot heat failure means icing could block the pitot system and render the ASI inoperative: the aircraft may be unairworthy for IFR in potential icing
    • Check your aircraft's POH Kinds of Operations and MEL for specific requirements

    Common wrong answers

    • Thinking pitot heat is always explicitly required by FAR for all IFR
    • Not checking the POH's Kinds of Operations section
    • Ignoring pitot heat failure when icing is forecast

    Source14 CFR §91.205; 14 CFR §91.213; POH Section 2

21. Question 21 · IR.II.A.K3

    What equipment is required to fly in RVSM airspace (between FL290 and FL410)?

    What a DPE expects to hear

    • RVSM = Reduced Vertical Separation Minima — 1,000-foot vertical separation FL290 to FL410
    • Required equipment per §91.180 and AC 91-85B:
    • Two independent altitude measurement systems (two altimeters)
    • An altitude alerting system
    • An automatic altitude control system (autopilot with altitude hold)
    • A secondary surveillance radar (SSR) transponder (Mode C or Mode S with altitude reporting)
    • The aircraft must be RVSM-approved and the operator must have Letter of Authorization (LOA) or equivalent
    • Part 91 operators require a Letter of Authorization (LOA) from the FAA for RVSM operations
    • If RVSM equipment fails en-route: must advise ATC immediately and may be assigned non-RVSM altitudes

    Common wrong answers

    • Thinking any aircraft can fly RVSM if at FL290
    • Not knowing the autopilot altitude hold requirement
    • Not knowing the LOA requirement for Part 91

    Source14 CFR §91.180; AC 91-85B; AIM 4-6-1