How many questions are on the FAA instrument written test?

The FAA Instrument Rating Airplane (IRA) knowledge test contains 60 multiple-choice questions. You have 2 hours and 30 minutes to complete it, and you need to score at least 70% to pass. The test is administered at PSI testing centers and costs approximately $175. Your results are valid for 24 calendar months, meaning you must complete your instrument checkride within that window or retake the knowledge test.

What's a good score on the instrument written test?

70% is passing, but aim for 85% or higher. Your DPE receives your score report and is required to cover any missed subject areas during the oral portion of your checkride. A low pass (70–75%) means your examiner will drill deep into your weak areas. A strong score signals preparation and shortens the oral. Most students who prepare adequately with adaptive practice score in the mid-80s to low 90s.

Do I need to take the written before starting instrument training?

No. FAR 61.65 requires the knowledge test be completed before the practical test, but not before flight training begins. Most students take the written midway through instrument training — after they've flown enough approaches, holds, and IFR cross-countries that the material has real context. Taking it too early means memorization without understanding; taking it too late delays your checkride.

What's the 1-2-3 rule for IFR alternates?

Per FAR 91.169, an alternate airport is required on your IFR flight plan unless, for at least 1 hour before to 1 hour after your ETA, the destination weather is forecast to have a ceiling of at least 2,000 feet and visibility of at least 3 statute miles. If any of those conditions aren't met in the forecast, you must file an alternate that meets the standard alternate minimums (600/2 for precision, 800/2 for non-precision).

How often do I need to check the VOR for IFR flight?

FAR 91.171 requires an operational VOR check within the preceding 30 days before using VOR for IFR navigation. Tolerances are ±4° for a VOT or ground checkpoint, ±6° for an airborne checkpoint, and ±4° between two VORs in a dual check. You must log the date, place, bearing error, and sign the entry. This is one of the most frequently tested regulations on the IRA knowledge test.

How long does it take to prepare for the instrument written test?

Most students spend 40–80 hours of study over 4–8 weeks. If you use adaptive practice software rather than random question drilling, you can compress this significantly — often to 20–30 hours of focused study. Key factors: whether you have prior instrument ground school, how strong your weather knowledge is, and how comfortable you are with chart interpretation. Full-length practice tests should be your final gate before scheduling.

Can I use scratch paper or a calculator on the IRA test?

Yes. PSI testing centers provide scratch paper and a basic on-screen calculator. You can bring a non-programmable calculator (such as an E6B electronic flight computer) but its memory must be cleared. You'll also have access to the FAA supplement booklet with charts, figures, and approach plates referenced by the questions. No personal notes, phones, smartwatches, or study materials are permitted in the testing room.

What happens if I fail the instrument written test?

You can retake it, but you'll need a new endorsement from an authorized instructor stating you've received additional training on the deficient areas and are competent to pass. There's no mandatory waiting period, but most students retake within 1–2 weeks after focused review. Each attempt costs another $175. The best strategy is to not fail in the first place: consistently score 85%+ on full-length practice tests before scheduling.

Instrument Written Test Practice Questions

The FAA Instrument Rating Airplane (IRA) knowledge test is 60 questions, 2.5 hours, and requires a 70% to pass. Most students who fail don't fail because instrument flying is hard — they fail because they practiced generic questions instead of the specific formats the FAA actually uses: holding entries from a printed depiction, alternate minimums logic, IFR fuel reserves, and chart symbology from the low-altitude enroute plates.

This page gives you a real practice environment for the IRA test: question types drawn from the current FAA test bank, explanations that cite the source document, and adaptive drilling that focuses on your weak areas instead of asking you the same easy stuff you already know.

What's on the FAA Instrument Rating knowledge test

The IRA test is built from the Instrument Rating – Airplane Airman Certification Standards (ACS). Every question maps to a specific ACS code. The test breaks down roughly like this:

Topic Area	Approx. % of Test	Primary References
Regulations (Part 61, Part 91)	15–20%	FAR 61.65, FAR 91.167, FAR 91.169, FAR 91.171
Weather and weather services	15–20%	AC 00-6, AC 00-45
IFR navigation systems (VOR, GPS, ILS)	15–20%	Instrument Flying Handbook, AIM 1-1
Departure, en route, arrival procedures	15%	AIM 5-2, 5-3, 5-4
Approach procedures and minimums	15%	TERPS, AIM 5-4
Aeromedical, aerodynamics, spatial disorientation	5–10%	Pilot's Handbook of Aeronautical Knowledge
Flight planning and performance	5–10%	AIM, POH

You need 70% to pass, but scoring in the low 70s means your DPE will grill you on every missed subject area during the oral. Aim for 85%+ on your knowledge test if you want a smooth checkride.

Eligibility before you sit for the test

Per FAR 61.65, to be eligible for the instrument rating you must:

Hold at least a private pilot certificate (or apply concurrently)
Be able to read, speak, write, and understand English
Receive and log ground training from an authorized instructor or complete a home-study course
Receive a logbook endorsement from an instructor certifying you're prepared for the knowledge test
Log 50 hours of cross-country PIC time (at least 10 in airplanes for the airplane rating)
Complete 40 hours of actual or simulated instrument time, including 15 hours with a CFII

The knowledge test itself has no minimum flight time — you can take it before you've flown a single approach. Most students take it midway through instrument training so the material is fresh but you have context.

The four regulations you'll see over and over

The IRA test hammers four Part 91 rules. Know them cold.

FAR 91.167 — Fuel requirements for IFR flight

You must have enough fuel to:

Fly to the first airport of intended landing
Fly from that airport to the alternate (if one is required)
Fly for 45 minutes after that at normal cruise consumption

Expect scenario questions: given a route, groundspeed, and fuel burn, calculate minimum required fuel. FAR 91.167 is the source.

FAR 91.169 — IFR flight plan: alternate airport requirements

The famous 1-2-3 rule: an alternate is required unless, for at least 1 hour before to 1 hour after your ETA, the destination weather is forecast to be at least 2,000 ft ceiling and 3 SM visibility.

Standard alternate minimums (when the alternate has published approach procedures):

Precision approach: 600 ft ceiling / 2 SM visibility
Non-precision approach: 800 ft ceiling / 2 SM visibility
No IAP available: descent from MEA, approach, and landing in VFR conditions

See FAR 91.169 for the full text.

FAR 91.171 — VOR equipment check for IFR

Before using VOR for IFR, it must have been operationally checked within the preceding 30 days. Tolerance limits:

VOT check: ±4°
Ground checkpoint: ±4°
Airborne checkpoint: ±6°
Dual VOR check (against each other): ±4°

You must log the date, place, bearing error, and signature. See FAR 91.171.

FAR 61.65 — Instrument rating requirements

Beyond eligibility, know the specific aeronautical experience: 40 hours instrument time, of which up to 20 can be in an approved FTD/ATD, and one 250 NM IFR cross-country with three different kinds of approaches. Full detail at FAR 61.65.

The question types that trip students up

After reviewing thousands of student attempts, these are the categories where the failure rate is highest:

Holding pattern entries from a printed depiction (direct, teardrop, parallel)
Alternate minimums logic — students memorize 600/2 and 800/2 but forget the 1-2-3 rule triggers the requirement in the first place
Chart symbology on low enroute charts (MEA, MOCA, MRA, MCA, changeover points)
Approach chart minimums — reading the minima line for the correct category and approach type
Weather chart interpretation — prog charts, radar summary, icing and turbulence products
GPS approach requirements — WAAS vs. non-WAAS, RAIM prediction, LPV vs. LNAV/VNAV
Lost communications procedures under AVEF/MEA (Assigned, Vectored, Expected, Filed)

If you're getting these wrong in practice, don't just re-read the answer — drill 20 more of the same type until the pattern is automatic.

How to actually study for the IRA

Read the source material once. The Instrument Flying Handbook (FAA-H-8083-15) plus the IPH cover 90% of the test. Don't skip the weather chapters.
Take a diagnostic test. 60 questions, no studying. See where you sit.
Drill by subject area, not randomly. If regulations are your weak spot, do 100 straight regulation questions until you're above 90%.
Simulate the real test. 60 questions, 2.5 hours, no notes, no breaks. Repeat until you're consistently at 85%+.
Get your endorsement and take the test within a week — while it's fresh.

The test costs about $175 at a PSI testing center, and your knowledge test results are valid for 24 calendar months — take your checkride within that window.

How GroundScholar helps with this

GroundScholar's instrument practice engine draws from the current FAA IRA question bank and tags every question with its ACS code and source document. When you miss a question on alternate minimums, the explanation cites FAR 91.169 directly — verified against the live regulation, not a five-year-old textbook.

The adaptive engine tracks which ACS areas you're weak in and biases future questions toward those. Instead of grinding 1,000 random questions, you spend your study time on the 200 that will actually move your score. When you're ready, run a full-length mock knowledge test with pass-prediction, then transition to the oral exam simulator to start prepping for the checkride the same day.

Ready to drill?

Start with a free diagnostic, then let the adaptive engine build your study plan. Every question is tied to a real ACS code and a real FAR — no generic wrong-answer traps, no outdated cites.

Start free →