Task VII.D
Approach with Loss of Primary Flight Instrument Indicators
To determine the applicant exhibits satisfactory knowledge, risk management, and skills associated with performing an approach solely by reference to instruments with the loss of primary flight control instruments.
References: 14 CFR part 91; FAA-H-8083-2, FAA-H-8083-3, FAA-H-8083-15, FAA-H-8083-16, FAA-H-8083-25; POH/AFM; Terminal Procedures Publications
Quick Review
Conversational Q&A — quiz yourself before the oral.
A warning indicator or flag, or an inconsistency between the attitude indicator and the supporting performance instruments. When something disagrees, expedite the cross-check and include all flight instruments — the problem may be a single instrument or a system failure taking out several at once (IFH ch. 11).
Immediately compare the attitude indicator against the rate-of-turn indicator and the VSI. Besides giving pitch and bank information, that comparison cross-checks the suction/pressure system (AI) against the electrical system (turn indicator) and the static system (VSI) — identify the failed component, then fly the remaining functional instruments (IFH ch. 11).
- It takes out the attitude indicator and heading indicator — and they can fail progressively: as the gyros spin down they wander, indications you can easily misinterpret if you fail to see the OFF or failed flags
- Wandering gyros can feed incorrect movement or erroneous indications to an autopilot or flight director
- Many small aircraft have no vacuum failure warning, so the pilot must monitor the vacuum/pressure gauge
An unnoticed failure can lead you into an unusual attitude that then demands a partial-panel recovery (IFH ch. 11).
A static system problem affects the ASI, altimeter, and VSI (IFH ch. 11).
- Select the alternate static source — location and operation per the POH/AFM
- With no alternate source, in an unpressurized airplane, you can break the glass on the VSI — it isn't required for instrument flight — giving the altimeter and ASI a static source, though this can introduce additional instrument errors (IFH ch. 11)
The system reverts to reversionary mode: the multi-function display (MFD) presents the primary flight display (PFD) instruments combined with the engine indicating system (IFH ch. 11). If instead the attitude and heading reference system (AHRS) fails, you're on partial panel — every maneuver except the instrument takeoff can be flown that way (IFH ch. 7). Either way you also have the standby instruments: standby attitude indicator, altimeter, ASI, and the magnetic compass (IFH ch. 11).
Glass panels power the AHRS, air data computer, PFD, and engine indications electrically — so a charging-system failure that was an abnormality in a round-dial airplane is an emergency in a technically advanced one (IFH ch. 11).
- Main battery: roughly 30–40 minutes of useful voltage, an approximation you must not lean on
- The standby battery (switch must be ARMed) comes online as the main battery depletes and powers the essential bus: AHRS, ADC, PFD, Nav 1, Com 1, standby indicator light
- Load-shed and land as soon as practical — never continue a flight after the charging system fails (IFH ch. 11)
Yes. Under IFR in controlled airspace you must report any malfunction of navigational, approach, or communication equipment as soon as practical (91.187), including:
- Aircraft ID
- Equipment affected
- Degree your IFR capability is impaired
- Nature and extent of assistance desired
Advise ATC or the evaluator if you're unable to comply with a clearance (IR.VII.D.S1), and declare an emergency before the situation deteriorates beyond your ability to recover (IFH ch. 11).
Two tools (IFH ch. 7):
- Timed turns — at standard rate, 3° per second; bank for standard rate ≈ 15 percent of TAS (divide airspeed by 10, add half: 100 knots → 15° of bank)
- Compass turns — usable, but only if you respect the magnetic compass's lead/lag errors (next card)
With 15°–18° of bank, lead or lag approximately equals your latitude (IFH ch. 7):
- Turning to north: the compass lags — lead the roll-out by your latitude plus normal roll-out lead
- Turning to south: the compass leads — turn past south by your latitude minus roll-out lead
- Turning to east or west from north: lead by about 10°–12°; from south: about 5°
- On east/west headings, acceleration indicates a turn toward north, deceleration toward south; on north/south headings, speed changes cause no error (IFH ch. 7)
The altimeter becomes your primary pitch reference, with the VSI backing it up (IFH ch. 7).
- First stop the needle movement with a smooth input, then pitch back toward the entry altitude
- Target a vertical speed about double the altitude deviation — 200 feet off, correct at 400 fpm — capped at an optimum 500–1,000 fpm
- Avoid abrupt control movements; overcontrolling turns one deviation into a series of them (IFH ch. 7)
A radar approach for when your directional gyro or stabilized compass is inoperative or inaccurate: advise ATC and request a no-gyro vector or approach. The controller says "turn right … stop turn" — you make standard-rate turns, executing immediately on each instruction, and switch to half standard rate once turned onto final (IFH ch. 10; IPH ch. 4).
Complete a nonprecision instrument approach without the use of the primary flight instruments, flown to the same skill elements as the nonprecision approach Task (Area VI, Task A) — while using the secondary/standby displays properly (IR.VII.D.R1) and keeping ATC in the loop (IR.VII.D.S1).
Deep Dive
Triage discipline — control first, diagnosis second
Aircraft control must be maintained while identifying the failed components (IFH ch. 11). Failed-instrument accidents come from the pilot fixating on the sick instrument — the same fixation error from basic attitude flying, with higher stakes. Once identified:
- Attempt to restore it — check the power source, switch to a backup or alternate system, reset the instrument if possible (IFH ch. 11)
- Cover the failed instruments — covering them may enhance your ability to maintain aircraft control and navigate (IFH ch. 11)
- Advise ATC, and if necessary declare an emergency before things deteriorate (IFH ch. 11, 91.187)
Knowing what to check requires knowing what powers what: consult the POH/AFM for the power source of every instrument before you ever need the answer in flight (IFH ch. 5).
Why this failure produces unusual attitudes
Unusual attitudes result from instrument failure, confusion, preoccupation, and errors in interpretation among other causes (IFH ch. 7) — a dying gyro that wanders while its failed flags go unnoticed is a machine for producing exactly that confusion (IFH ch. 11). During recovery, remember the attitude indicator itself may not be trustworthy: don't depend on a spillable-type AI whose limits may have been exceeded (IFH ch. 7). Recover on the instruments you've verified.
Glass-cockpit electrical strategy
One recommended technique: switch the MASTER side off to take the main battery offline — with the standby battery ARMed, it comes online to power the essential bus. Using the standby battery first reserves the main battery for the approach, when you'll want flaps, gear, and lights. Don't count on any power after the standby battery is exhausted — the flight deck may go completely dark, and navigation falls back to pilotage/dead reckoning unless you carry a handheld with GPS (IFH ch. 11).
Radar as a backup instrument
When the panel degrades, ATC's radar can substitute for a surprising amount of it. Beyond no-gyro vectors:
An airport surveillance radar approach gives heading and range only — the controller can also advise recommended altitudes each mile on final, if you ask (IFH ch. 10). Design protections (IPH ch. 4):
- Final approach course aligned with the runway centerline (straight-in) or the airport center (circling)
- 250 feet minimum obstacle clearance in the final approach area
- Flat descent gradients — optimally 150 feet per mile, never exceeding 300
ASR approaches are typically approved only for ATC operational needs or unusual/emergency situations — a partial-panel day qualifies (IPH ch. 4).
Preventing the whole scenario
Preflight: pay particular attention to the alternator belt, antennas, static wicks, anti-ice equipment, pitot tube, and static ports.
Taxi: verify flight instrument operation and accuracy.
Run-up: confirm the pneumatic system reads within acceptable parameters.
All systems should be verified operational before departing into IFR conditions (IFH ch. 11) — and in a glass airplane, the standby battery must be armed before departure for its automatic protection to work (IFH ch. 11).
Official ACS elementsreference
Knowledge2 elements
The applicant demonstrates understanding of:
IR.VII.D.K1Recognizing if primary flight instruments are inaccurate or inoperative, and advising ATC or the evaluator.IR.VII.D.K2Possible failure modes of primary instruments and how to correct or minimize the effect of the loss.
Risk Management3 elements
The applicant is able to identify, assess, and mitigate risk associated with:
IR.VII.D.R1Use of secondary flight displays when primary displays have failed.IR.VII.D.R2Maintaining aircraft control.IR.VII.D.R3Distractions, task prioritization, loss of situational awareness, or disorientation.
Skills3 elements
The applicant exhibits the skill to:
IR.VII.D.S1Advise ATC or the evaluator if unable to comply with a clearance.IR.VII.D.S2Complete a non-precision instrument approach without the use of the primary flight instruments using the skill elements of the non-precision approach Task (see Area of Operation VI, Task A).IR.VII.D.S3Use single-pilot resource management (SRM) or crew resource management (CRM), as appropriate.