GRABCARDD: The Required Instrumentation for IFR Flight (91.205d) Explained
Updated: Sep 26
Flying under Instrument Flight Rules requires more than pilot proficiency and a clearance — it requires an aircraft equipped with specific instruments that allow safe operation when outside visual references are unreliable or unavailable. The FAA defines these requirements in 14 CFR 91.205(d), and pilots remember them with the acronym GRABCARDD. But the acronym has a couple of points worth understanding beyond memorizing the letters: it ADDS to the day and night VFR equipment (it's not a standalone list), the double-D is intentional (two different items), and several of the instruments are the "gyroscopic" group that fails together in a vacuum failure — which is why partial-panel skill matters. Understanding GRABCARDD as the IFR addition to the equipment stack, and knowing which instruments do what, is a foundation of legal IFR flight.
This post covers required IFR instrumentation in practical depth: the 91.205(d) foundation and how it stacks on VFR equipment, each GRABCARDD item, why there are two D's, the gyroscopic instrument grouping and partial panel, the pitot-static instruments, the inspections that make IFR equipment legal, and inoperative-equipment rules.
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The Regulatory Foundation: 14 CFR 91.205(d)
Section 91.205(d) specifies the instruments and equipment required for IFR flight — IN ADDITION to those required for VFR.
The additive structure (important):
91.205(b): day VFR (ATOMATOFLAMES)
91.205(c): night VFR — adds FLAPS
91.205(d): IFR — adds GRABCARDD
IFR requires ALL of the above: day VFR + night (if at night) + the IFR additions
What this means:
GRABCARDD is NOT the complete IFR equipment list by itself
It's the IFR ADDITION to the VFR equipment
For an IFR flight, you need the day VFR equipment (ATOMATOFLAMES) PLUS GRABCARDD (and FLAPS if at night)
The lists stack
What the IFR instruments enable:
Control the aircraft solely by reference to instruments
Navigate accurately in the IFR system
Communicate with ATC
Maintain situational awareness in IMC
The legal baseline:
GRABCARDD is not optional — it's the legal minimum for IFR (added to VFR)
Missing/inoperative IFR equipment (not deferred) = not legal for IFR
The pilot verifies before an IFR flight
Part of IFR airworthiness
The GRABCARDD Acronym Explained
Each item with what it does and the practical considerations.
G — Generator or Alternator:
A reliable electrical power source capable of supplying all required IFR equipment
Powers navigation radios, avionics, gyros (if electric), and lighting
Note: this is the same electrical-source requirement as night VFR (the "S" in FLAPS) — for IFR, it's explicitly required
Practical: understand electrical load management, know your battery-only endurance, monitor the ammeter/voltmeter in IMC
R — Radios (Comm and Nav):
Communication AND navigation radios appropriate for the route/approaches
IFR depends on constant ATC communication (clearances, instructions, separation)
Nav radios for navigation (VOR, ILS, or GPS as appropriate)
Practical: verify the audio panel, mic, headset; backup radios recommended (not required); lost-comms procedures assume failure
A — Attitude Indicator:
Provides pitch and bank information
The PRIMARY instrument for aircraft control in IMC
Essential for preventing spatial disorientation
Practical: vacuum vs. electric-driven; recognize gyro failure; glass cockpits still need a reliable attitude source (with backup)
B — Ball (Slip-Skid Indicator):
Shows lateral coordination (the inclinometer)
Often part of the turn coordinator
Helps maintain coordinated flight (prevents unrecognized slips/skids in IMC)
Practical: important in turns and holds; critical during partial-panel
C — Clock (with a sweep-second or digital display):
Must display hours, minutes, and SECONDS
For timing approaches, holding leg timing, missed approach timing
Practical: panel-mounted clocks common; a GPS clock may qualify if always visible/reliable; backup timing recommended
A — Altimeter (sensitive, adjustable):
A SENSITIVE altimeter, adjustable for barometric pressure
Provides vertical position for altitude assignments and obstacle clearance
Note: an altimeter is also required for VFR, but IFR specifies a SENSITIVE, adjustable one
Practical: set the correct altimeter setting; understand cold-temperature altitude errors; verify static system integrity
R — Rate of Turn Indicator:
Shows the rate of heading change (the turn coordinator or turn-and-slip)
Allows precise turns when the horizon isn't visible (standard-rate turns, holds)
Practical: often combined with the slip-skid (the "ball"); understand standard-rate (3°/sec) vs. half-standard
D — Directional Gyro (Heading Indicator):
The FIRST D: the directional gyro / heading indicator
Provides a stable directional reference (easier than the magnetic compass)
Critical for precise navigation and tracking courses
Practical: align periodically with the magnetic compass; glass cockpits use electronic heading; watch for precession
D — DME or a Suitable RNAV System (as required):
The SECOND D: Distance Measuring Equipment (DME) or a suitable RNAV system
Required IF the route or approach requires it (or above FL240 if VOR is required for navigation)
Determines distance to fixes; required for certain approaches, holds, and routes
Practical: GPS often satisfies the DME requirement (if approved); equipment must be IFR-certified; check approach notes
Why There Are Two D's
A point worth making explicit, since the double-D confuses people.
The double-D is intentional:
GRABCARDD has TWO D's — they're different items
First D: Directional Gyro (heading indicator)
Second D: DME (or suitable RNAV substitute)
Not a typo — two separate requirements
Why they're both D:
Directional gyro starts with D
DME starts with D
Both are IFR requirements
Hence the double-D acronym
The distinction:
Directional Gyro: your heading reference (always required for IFR)
DME: distance measuring (required as the route/approach demands, often satisfied by GPS)
Different functions, both "D"
Remember there are two
The "as required" nature of the second D:
The directional gyro (first D) is always required for IFR
The DME (second D) is required WHEN the route or approach requires it (or above FL240 with VOR)
The second D is conditional
GPS usually satisfies it
The Gyroscopic Instruments and Partial Panel
A grouping the basic treatment doesn't highlight but that matters for understanding failures.
The three gyroscopic instruments:
Attitude Indicator (A)
Rate of Turn Indicator / Turn Coordinator (R)
Directional Gyro / Heading Indicator (D, the first one)
These three are the gyro instruments
The vacuum-system connection:
In many traditional aircraft, the attitude indicator and directional gyro are VACUUM-driven (by an engine-driven vacuum pump)
The turn coordinator is often ELECTRICALLY driven (a deliberate split for redundancy)
So a vacuum failure takes out the AI and DG, but the (electric) turn coordinator survives
This split is intentional
Why the split matters — the vacuum failure:
If the vacuum pump fails, you lose the attitude indicator and directional gyro
You're left with the turn coordinator (electric), plus the pitot-static instruments (altimeter, airspeed, VSI) and the magnetic compass
This is "partial panel" flying
A critical IFR skill
Partial-panel flying:
Flying without the primary gyro instruments (AI, DG)
Using the turn coordinator, pitot-static instruments, and compass
Controlling attitude indirectly (the "compass turns," timed turns, airspeed/VSI for pitch)
Practiced and tested (part of the IPC and instrument checkride)
The glass-cockpit consideration:
Glass cockpits (electronic) don't have vacuum gyros
But they have their own failure modes (screen failure, ADAHRS failure, electrical)
Backup instruments (a standby attitude indicator, or a backup electronic display) are required/standard
Understand YOUR aircraft's failure modes and backups
Why this matters:
Understanding which instruments fail together (vacuum) prepares you for the failure
Partial-panel skill is essential (you WILL practice it)
The instrument grouping explains the failure scenario
Know your panel
The Pitot-Static Instruments
The instruments that carry over from VFR but are essential for IFR, worth clarifying.
The pitot-static trio:
Altimeter (in GRABCARDD as the sensitive, adjustable "A")
Airspeed Indicator (required for VFR too — ATOMATOFLAMES)
Vertical Speed Indicator (VSI) (not explicitly in GRABCARDD, but present and used)
The altimeter (the IFR "A"):
GRABCARDD specifies a SENSITIVE, adjustable altimeter for IFR
More precise than a basic altimeter
Adjustable for the current barometric setting
Critical for IFR altitude control
The airspeed indicator:
Required for VFR (ATOMATOFLAMES) — carries over to IFR
Essential for IFR (speed control, approach speeds)
Part of the pitot-static system
Always needed
The VSI:
Not explicitly required by 91.205, but present in IFR aircraft
Used for controlling climb/descent rates (approaches, level-offs)
A useful IFR instrument
Standard equipment
The pitot-static role in partial panel:
In a vacuum failure, the pitot-static instruments (altimeter, airspeed, VSI) still work (they're not gyro-driven)
They become primary references for pitch (with the turn coordinator for bank)
Essential for partial-panel flying
The backup
The pitot-static system integrity:
The pitot-static system must be functioning (and inspected — below)
Blockages cause instrument errors (a real IFR hazard)
Understand pitot-static failures (blocked pitot, blocked static)
Critical for IFR
The Inspections That Make IFR Equipment Legal
A connection the basic treatment doesn't make: IFR equipment must be inspected to be legal.
The pitot-static/altimeter inspection (91.411):
Required every 24 CALENDAR MONTHS for IFR
Tests the altimeter, static system, and altitude reporting
Required to fly IFR
Without it, the aircraft isn't legal for IFR (even with the instruments installed)
The transponder inspection (91.413):
Required every 24 calendar months
The transponder (required for the airspace) must be inspected
Often done with the pitot-static inspection
Part of IFR airworthiness
The VOR check (91.171):
If using VOR for IFR navigation, a VOR check within 30 days
The pilot can do it
Required for IFR VOR navigation
(Covered in the required-inspections post)
Why inspections matter for IFR:
Having the IFR instruments isn't enough — they must be inspected/current
The pitot-static and transponder inspections (24 months) are IFR prerequisites
The VOR check (30 days) for VOR navigation
Verify these before an IFR flight
The airworthiness picture:
IFR airworthiness = the required instruments (GRABCARDD + VFR) + the inspections (pitot-static, transponder, VOR) + operational equipment
All required for legal IFR
The pilot verifies
Comprehensive
GRABCARDD vs. Real-World IFR Needs
The minimum vs. the smart setup, expanded.
GRABCARDD is the minimum, not the ideal:
It defines the LEGAL minimum equipment
Not the ideal setup for challenging IFR
Legal ≠ smart in demanding conditions
A floor, not a goal
Most IFR pilots also rely on:
Redundant attitude sources (a backup AI, or a second electronic display)
Backup navigation (a second GPS, or a handheld)
Autopilots (huge workload reduction in IMC)
Moving maps and weather displays (situational awareness)
ADS-B In (traffic and weather)
Why more than the minimum:
IFR is demanding (workload, no visual references)
Redundancy handles failures
Automation reduces workload
The minimum leaves little margin
The personal-minimums angle:
Consider what equipment YOU want for the conditions
A minimally equipped aircraft in hard IFR is riskier
Match the equipment (and your minimums) to the mission
Smart, not just legal
What Happens If Something Fails?
The inoperative-equipment picture, expanded.
If required IFR equipment becomes inoperative:
The aircraft may not be legal for IFR
A Minimum Equipment List (MEL) may apply (if the aircraft has one)
Otherwise, 91.213 governs inoperative equipment
Deferral rules apply
The MEL path:
If the aircraft has an MEL, follow it for inoperative equipment
The MEL may allow deferring certain IFR equipment (with conditions)
(Covered in the MEL post)
Structured deferral
The 91.213(d) path (no MEL):
For aircraft without an MEL
The equipment can be deferred only if not required for the operation (IFR here), not on the equipment list/KOEL, not required by 91.205, not required by an AD
IFR-required equipment (GRABCARDD) generally can't be deferred for IFR
An inoperative IFR item usually grounds the aircraft for IFR (but may allow VFR)
The IFR-to-VFR downgrade:
If an IFR-only item fails (e.g., the attitude indicator in a way that affects IFR), the aircraft may still be legal for VFR
You could potentially fly VFR (if the VFR equipment is intact)
But not IFR
The operation determines what's required
The in-flight failure:
If IFR equipment fails in flight (in IMC), it's an emergency situation
Partial panel, declare if needed, get to VMC or an approach
Handle the failure
Why partial-panel skill matters
Never assume "it'll probably work":
IFR failures often happen at the worst time (in IMC)
Verify equipment before the flight
Don't launch into IMC with questionable equipment
Conservative
Common IFR Instrumentation Mistakes
The errors, expanded.
Forgetting to verify the clock:
The clock (with seconds) is required
Easy to overlook
Verify it works (or have a backup)
A common miss
Assuming GPS always substitutes for DME:
GPS satisfies DME requirements only if APPROVED (IFR-certified)
Not all GPS units qualify
Verify your GPS is approved as a DME substitute
Check the approval
Not understanding glass-cockpit failure modes:
Glass cockpits fail differently (screens, ADAHRS, electrical)
Know the backups and failure modes
Don't assume glass is failure-proof
Understand YOUR system
Overlooking electrical system limitations:
The electrical source (G) powers everything
Know your battery endurance (electrical failure in IMC)
Monitor the electrical system
A critical consideration
Confusing VFR-only equipment with IFR-approved systems:
Some equipment is VFR-only (not IFR-certified)
IFR requires IFR-approved equipment
Verify certification
Don't use VFR-only gear for IFR
Forgetting the inspections:
The pitot-static and transponder inspections (24 months) are IFR prerequisites
Having the instruments isn't enough
Verify the inspections are current
An airworthiness miss
Practical Tips for IFR Pilots
Expanded advice.
Memorize GRABCARDD (and remember the two D's: Directional gyro and DME)
Physically verify each item during preflight
Understand how each instrument fails (especially the vacuum gyros)
Practice partial-panel flying regularly
Know your electrical system and battery endurance
Verify the IFR inspections (pitot-static, transponder, VOR) are current
Brief the equipment requirements for each approach (does it need DME? GPS?)
Consider redundancy for the conditions you fly
Final Thoughts
GRABCARDD is more than a memory aid — it's a safety framework. These instruments exist because IFR flying demands precision, redundancy, and reliability when visual references disappear. Understanding it fully means knowing that it ADDS to the VFR equipment (it's not a standalone list), that the double-D is intentional (Directional gyro and DME), that the gyroscopic instruments (attitude, rate of turn, directional gyro) fail together in a vacuum failure (why partial-panel skill matters), and that the IFR inspections (pitot-static, transponder) are prerequisites alongside the instruments themselves.
Knowing what's required — and why — helps you stay legal, stay prepared, and stay safe in the IFR system. Master the equipment (and how it fails), and you'll be far better equipped to handle the environment that instrument flying demands.
On the Written Test and Checkride
Required IFR instrumentation appears on tests and checkride orals (instrument especially).
The most commonly tested topics:
The GRABCARDD items (91.205d)
That IFR equipment ADDS to VFR (ATOMATOFLAMES + FLAPS + GRABCARDD)
The two D's (Directional gyro and DME)
The gyroscopic instruments and partial panel (vacuum failure)
The IFR inspections (pitot-static, transponder, VOR)
Inoperative IFR equipment (MEL/91.213)
Quick Reference
91.205(d) — IFR (adds to VFR):
Day VFR (ATOMATOFLAMES) + night if applicable (FLAPS) + IFR (GRABCARDD)
IFR equipment is ADDITIVE to VFR
GRABCARDD:
G — Generator/Alternator (electrical source)
R — Radios (comm and nav)
A — Attitude Indicator
B — Ball (slip-skid indicator)
C — Clock (with seconds)
A — Altimeter (sensitive, adjustable)
R — Rate of turn indicator
D — Directional Gyro (heading indicator)
D — DME (or suitable RNAV, as required)
The Two D's (intentional):
First D: Directional Gyro (heading indicator) — always required
Second D: DME (or RNAV) — required as the route/approach demands (GPS usually satisfies)
The Gyroscopic Instruments:
Attitude Indicator (A)
Rate of Turn / Turn Coordinator (R)
Directional Gyro (D, first)
Vacuum failure: lose AI and DG (vacuum); turn coordinator (electric) survives → partial panel
Partial Panel:
Flying without the primary gyros (AI, DG)
Use turn coordinator + pitot-static (altimeter, airspeed, VSI) + compass
Essential IFR skill (practiced and tested)
Pitot-Static Instruments:
Altimeter (sensitive, adjustable — the IFR "A")
Airspeed indicator (from VFR)
VSI (present, used)
Survive a vacuum failure (become primary in partial panel)
IFR Inspections (prerequisites):
Pitot-static/altimeter (91.411): 24 calendar months
Transponder (91.413): 24 calendar months
VOR check (91.171): 30 days (for VOR nav; pilot can do)
Beyond the Minimum (recommended):
Redundant attitude source
Backup navigation
Autopilot
Moving map, weather, ADS-B In
If Equipment Fails:
May not be legal for IFR
MEL (if the aircraft has one) or 91.213(d)
IFR-required equipment generally can't be deferred for IFR
May still allow VFR
Common Mistakes:
Forgetting the clock
Assuming GPS always substitutes for DME (needs approval)
Not understanding glass-cockpit failures
Overlooking electrical limitations
Confusing VFR-only with IFR-approved equipment
Forgetting the IFR inspections
Key Principle:
GRABCARDD is the IFR instrumentation required by 91.205(d), ADDED to the VFR equipment (ATOMATOFLAMES + FLAPS). The double-D is intentional: Directional gyro (always required) and DME (as required, usually satisfied by GPS). The gyroscopic instruments (attitude, rate of turn, directional gyro) fail together in a vacuum failure — leaving the turn coordinator and pitot-static instruments for partial panel, a critical IFR skill. And the IFR inspections (pitot-static and transponder, 24 months) are prerequisites alongside the instruments.
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Author: Nathan Hodell
CFI, CFII, MEI, ATP, Creator and CEO
Nathan is an aviation enthusiast with thousands of hours of flying and dual instruction over the past 15+ years. Through his aviation career he has been able to earn his ATP, fly as an airline pilot, own/operate flight schools, and create and host wifiCFI.