IFR (New 11.14.26)

Claude helped to condense the information. Went from 600+ cards to around 350.

What are your IFR Privileges and Limitations?

Privileges

→ Fly in IMC (IFR flight plan)

→ Fly Special VFR at night (sunset to sunrise)

→ Can act as a Safety Pilot

Limitations

→ Currency (6-HITS)

→ Aircraft must be equipped/approved for IFR.

→ Cannot be paid / work for hire.

When is an instrument rating required?

→ Under IFR (on an IFR flight plan)

→ In weather below VFR minimums

→ In Class A airspace (18,000' MSL and above)

→ Special VFR in B, C, D, E surface areas (sunset to sunrise)

→ Commercial: carrying passengers for hire on XC > 50 NM or at night

What is Special VFR?

A legal way to depart or land in weather below VFR minimums, with ATC approval.

→ Visibility 1 SM and remain clear of clouds

→ Within the surface area of Class B, C, D or E airspace, below 10,000' MSL

→ Instrument rating required at night (sunset to sunrise)

Can you get an instrument rating in an airplane without a GPS?

Yes.

What flight experience is required for an Instrument–Airplane rating? (61.65)

→ 50 hr XC PIC (10 hr in airplanes)

→ 40 hr actual/simulated instrument time

→ 15 hr from an authorized instrument instructor

→ 3 hr instrument training in an airplane within 2 calendar months of the practical test

→ One IFR XC with an instructor: 250 NM, IFR flight plan, airways or ATC routing, an approach at each airport, 3 different types of approaches using nav systems

What is instrument currency? (61.57)

Does it have to be completed in an aircraft?

Within the preceding 6 calendar months, in actual or simulated conditions:

→ 6 instrument approaches

→ Holding procedures and tasks

→ Intercepting and Tracking courses through nav systems

May repeat the same approach.

Can be done in an aircraft, FFS, FTD or ATD.

What currency must be met to act as PIC under IFR?

→ Current flight review (24 calendar months)

→ Passenger currency (if carrying passengers): 3 takeoffs & landings in 90 days in same category/class/type; full stop if night or tailwheel

→ Instrument currency: 6-HIT within 6 calendar months

Your instrument currency lapses. What are the timelines?

→ First 6 calendar months: current (after checkride, IPC or 6-HIT)

→ Second 6 calendar months (grace period): NOT IFR legal, but may regain currency in simulated IFR with an appropriately rated safety pilot (or approved device) or flight simulator.

→ After 12 calendar months: Instrument Proficiency Check (IPC) by a DPE, CFII, check pilot or FAA person

IPC vs. Instrument Currency:

What's the difference?

What's on an IPC?

Currency: may repeat the same approach.

IPC: like a practical test; must demonstrate different approaches:

→ One precision approach or approach with a DA

→ One non-precision approach • One non-precision approach on partial panel / Plus holding, intercepting and tracking.

No formal ground training required.

May a simulator be used for instrument currency or training? Any limits?

Yes: FFS, FTD or ATD (properly certified)

→ Not every device is approved for every task (e.g., IPC). Verify the device is qualified for the intended use.

→ Simulator must represent the same category of aircraft

→ Log the device, time and content in a logbook or training record

→ Currency: instructor need not be present

→ Experience toward a certificate/rating: instructor must be present and sign the logbook

ATD vs. FTD

What's the difference?

ATD (Aviation Training Device):

→ Basic & Advanced

→ Used for training hours under an FAA letter of authorization.

FTD (Flight Training Device):

→ Qualified under Part 60

→ Common at flight schools and training centers.

Instrument current in a single-engine airplane. Are you also current in a multi-engine?

Yes. Approaches in a single-engine aircraft keep you instrument current in a multi-engine aircraft too (you still need the multi rating).

Actual vs. Simulated instrument time: When can you log it? (61.51)

When you operate the aircraft solely by reference to instruments.

Actual

→ In actual IMC

→ No safety pilot needed in actual IMC.

Simulated

→ View-limiting device with a safety pilot on board.

→ Doesn't have to be in the clouds for simulated.

What is flight time?

Begins when the aircraft starts moving under its own power to take off.

Ends when it comes to a full stop after landing.

When can you log an instrument approach (IAP)?

Sole manipulator of flight controls, by reference to instruments.

Actual

→ Must be in IMC at the FAF (breaking out after the FAF still counts).

Simulated

→ Under the hood with a safety pilot, descend to minimums (MDA or DA).

*Fly the whole IAP from an IAF/feeder, unless vectored or ATC clears you to a specific segment.

What must be in each logbook entry for instrument currency?

→ Location

→ Type of each instrument approach completed

→ Name of the safety pilot (if required)

What are the requirements to act as a safety pilot?

→ At least a Private Pilot Certificate

(category/class of the aircraft (ASEL for the Cessna).

→ Medical certificate

(3rd class or BasicMed if the aircraft qualifies - because the safety pilot is a required crewmember).

→ Instrument rating & current, if the flight is on an IFR flight plan

*Acts as eyes, keeping the flight safe during simulated instrument training.

Instrument-rated Private Pilot on BasicMed: can you fly IFR?

Yes, VFR or IFR.

The aircraft still has to be approved/equipped for IFR.

What are your PPL privileges?

→ Act as PIC; may work for a business if flying is incidental to it (no passengers for compensation)

→ Demonstrate an aircraft to a buyer if a salesperson with 200 hr

→ Act as PIC and Tow a glider (with the required experience).

What are your PPL limitations?

→ Flight review every 24 calendar months

→ Can only fly VFR (without an instrument rating)

→ Passenger currency: 3 T/O & landings in 90 days (full stop at night)

→ Cannot fly for compensation or hire

First-class medical: when is it needed and how long is it valid?

Needed

→ PIC of an ATP operation

→ SIC in an airline operation needing 3+ pilots.

Valid (1st-class privileges)

Under 40 = 12 calendar months

40 and over = 6 calendar months

Second-class medical: when is it needed and how long is it valid?

Needed

→ Commercial pilot privileges (flying for hire)

→ SIC privileges of an ATP in airline ops

Valid

→ 12 calendar months regardless of age.

Third-class medical: who needs it and how long is it valid?

Who

→ Private Pilots, Recreational, Student pilots, CFI

Valid

→ under 40 = 60 calendar months

→ 40 and over = 24 calendar months.

What are the BasicMed requirements and restrictions?

Requirements

→ Valid driver's license

→ Must have held an FAA medical before

→ Physical exam every 48 calendar months

→ BasicMed course every 24 calendar months.

Restrictions

→ Max takeoff weight 12,500 lb & Max 7 occupants (pilot + 6)

→ Below 18,000' MSL

→ 250 kt IAS max

→ No compensation or hire; fly in U.S. only.

What minimum equipment is needed for IFR?

IFR day = VFR day + GRABCARD

IFR night = VFR day + VFR night + GRABCARD.

→ Generator/alternator

→ Radios (two-way comm & nav for the route; transponder)

→ Altimeter (sensitive, adjustable; uses changes in ambient air pressure to determine altitude)

→ Ball (slip/skid)

→ Clock (hours, minutes, seconds)

→ Attitude indicator

→ Rate-of-turn indicator

→ Directional gyro (heading indicator)

At or above FL240 (if using VOR): DME or suitable RNAV. If the DME fails, notify ATC immediately and look to land.

What inspections are required for IFR?

→ Airworthiness Directives / Annual

→ VOR check (30 days)

→ 100-hour (only if for hire or flight instruction in an aircraft the instructor provides)

→ Altimeter / pitot-static (24 calendar months)

→ Transponder (24 calendar months)

→ ELT (12 calendar months)

→ Supplemental Type Certificate

What are the VOR check methods and allowable errors?

Where are checkpoints found?

→ VOT: ±4°

→ Repair station: ±4°

→ VOR ground checkpoint: ±4°

→ VOR airborne checkpoint: ±6°

→ Dual VOR cross-check: within 4° of each other

→ Checkpoints are in the Chart Supplement.

Set 360: needle centers with FROM;

Set 180: TO.

"I like warm weather; south is warm, so go TO the south (180)"

What must be recorded for a VOR check?

Date, Place, Error noted, Signature.

What documents are required on board?

→ Airworthiness certificate

→ Registration

→ Radio license (international flights)

→ Operating handbook (POH/AFM)

→ Weight & balance

→ Supplemental Type Certificate

How do you deal with inoperative equipment? (91.213)

→ Is it part of a Type Certificate? If no,

→ Is it part of an MEL? If so, follow it. If no,

→ Is it required by the KOEL (in the POH)? If no,

→ Is it required by 91.205 or other regs for this kind of flight?

→ Is it required by an Airworthiness Directive?

Yes to any: don't fly.

No to all: deactivate/remove, placard INOP, and fly.

GPS databases

How often updated?

Can a pilot update them?

Expired database?

→ Navigation database: every 28 days

→ Obstacle/terrain/airport maps: as needed (~56 days).

→ Pilot may update if it's done from the flight deck without disassembling the unit. Non-maintenance task; no logbook entry needed.

→ Fly IFR approaches only with a current database.

Can a handheld GPS be used for IFR?

No, VFR/handheld GPS units are not authorized for IFR navigation, approaches, or as a principal instrument reference.

They can be used to aid Situational Awareness only!

What must a PIC be familiar with before a flight? (91.103)

→ NOTAMs

→ Weather

→ Known ATC delays

→ Runway lengths

→ Alternatives available

→ Fuel requirements

→ Takeoff & Landing distances

Check the NAS status website for ATC delays.

How can you file and IFR flight plan?

When do you file an IFR flight plan?

How long will ATC wait to cancel an inactivated Flight Plan?

→ 1800wxbrief.com / 1-800-WX-BRIEF

→ FSS

→ EFB (ForeFlight),

→ ATC (pop-up clearance)

→ At least 30 minutes before departure (4 hours if flying above FL230)

→ ATC deletes an inactivated plan 2 hours after the proposed departure time

What Altitude and Speed go on the flight plan? (ICAO Item 15)

Altitude

Initial cruising altitude.

A + 3 digits in hundreds of feet (A170) or F + flight level (F330)

Speed

True airspeed for the first/whole cruise portion.

N + knots (N0485) or M + Mach (M082)

No person may operate in controlled airspace under IFR unless…

→ They have filed an IFR flight plan

→ Received an ATC clearance

How do you cancel an IFR flight plan?

When can you cancel it in the air?

How do you cancel your flight plan if you cannot reach ATC?

Towered

→ ATC cancels automatically upon landing

Non-towered

→ Pilot contacts ATC/FSS (radio or phone)

In the air

→ Any time you're in VFR conditions outside Class A

Can't reach anyone?

Try CTAF, 121.5, Center on local approach plate, call a tower.

So search and rescue doesn't come looking for you!

What are the IFR fuel requirements? (91.167)

Enough fuel to fly to:

1. The destination

2. Then the most distant alternate

3. Then 45 minutes at normal cruise

This is the same day or night.

When are you legally required to file an alternate? (91.169)

Either condition requires an alternate:

→ The destination has no (active) instrument approach, regardless of weather

OR

→ Weather from 1 hr before to 1 hr after ETA is forecast below 2,000' ceiling or 3 SM visibility (1-2-3 rule)

Scenario - Destination has no instrument approach, forecast 3,000' and 5 SM.

Do you need an alternate?

Yes.

The weather meets the 1-2-3 rule, but with no instrument approach an alternate is still required.

Picking an alternate - What three separate questions are you answering?

1. Do I need an alternate? (1-2-3 rule, 91.169)

2. Can I base it on a GPS approach? (equipment rules: WAAS, non-WAAS)

3. Does the forecast meet alternate minimums at my ETA? (600-2 / 800-2, or the A-symbol minimums)

When do you use Precision 600-2 and Non-Precision 800-2?

Only for filing an alternate, never for flying an approach.

Compare against the forecast at your ETA at the alternate:

→ Precision approach available: 600' ceiling & 2 SM

→ Non-precision only (VOR, LOC, LNAV): 800' ceiling & 2 SM

→ No instrument approach: must be able to descend from the MEA, approach and land under basic VFR

“A” symbol: non-standard alternate minimums replace these / If you divert there, fly the published approach minimums.

When does an airport NOT qualify as an alternate?

→ Its NAVAID is unmonitored

→ It has no weather reporting

→ The A symbol says alternate NA

What weather resources determine whether you need an alternate or can use an airport as one?

→ TAF (Terminal Aerodrome Forecast)

→ GFA (Graphical Forecasts for Aviation)

Non-WAAS GPS: Where can you count on a GPS approach for planning?

Destination or alternate, not both. The other end needs a ground-based approach (ILS/LOC/VOR).

Reason: RAIM can fail; if GPS goes down, you still have a way down somewhere.

Scenario: non-WAAS, destination and alternate both GPS-only: not plannable as filed.

WAAS (your G1000): can you file an alternate that only has an RNAV (GPS) approach?

Yes, regardless of what's at the destination.

→ Plan on LNAV or circling minimums only, not LPV or LNAV/VNAV, even if LPV is published.

→ Why: WAAS vertical guidance can't be guaranteed hours ahead; lateral can. Plan LNAV, then fly the LPV if it's available on arrival. The rule restricts planning, not flying.

Does ATC know your filed alternate?

After a missed approach, can you go somewhere else?

No, filed alternates are not displayed to controllers.

→ You may divert to any airport you judge safest (weather, fuel); you're not required to use the filed alternate.

If able, tell ATC and request an amended clearance. If you can't reach ATC, proceed to your alternate or another safe airport.

What are preferred IFR routes and where are they found?

→ Established routes between busier airports to increase system efficiency and capacity.

→ Found in the Chart Supplement (toward the back) and ForeFlight.

What is IMC?

Instrument Meteorological Conditions

Weather below VFR minimums (Ceiling below 1,000' or visibility below 3 SM)

What is RVR?

Runway Visual Range

How far down the runway a pilot can see, measured by instruments, in feet (e.g., RVR 2400).

What counts as a cloud ceiling?

The lowest broken (BKN) or overcast (OVC) layer

or

The vertical visibility into an obscuration phenomenon (e.g., fog, smoke, volcanic ash).

What is pressure gradient force?

The force that pushes air from high to low pressure, creating wind.

→ Close isobars: strong gradient (strong winds, turbulence, possible wind shear)

→ Wide isobars: weak gradient (light winds)

What is the freezing level and how do you find it?

The altitude where temperature is 0°C (32°F).

Find it from freezing-level graphics or the temperatures on the Winds Aloft forecast.

What are the four types of fog and their causes?

Radiation: calm, clear nights over low, flat ground; ground cools the air to its dew point

Advection*: warm, moist air moves over a cooler surface; common on coastlines.

Upslope*: warm air pushed up sloping terrain, rises and cools; needs wind

Steam*: cold, dry air over warm water; indicates instability

*requires wind.

Decode wind barbs on a winds aloft chart.

Pennant (dark triangle): 50 kt

Long line: 10 kt

Short line: 5 kt

Open circle: calm

The shaft points toward the direction the wind is coming from.

What is a microburst?

The strongest form of wind shear; can happen at any altitude.

→ Downdraft up to 6,000 fpm

→ Under 1 mile across, spreading to about 2.5 mi at the surface

→ Winds up to 45 kt (90 kt headwind-to-tailwind shear)

→ Usually lasts 5–15 minutes

Sequence: headwind gain, then downdraft, then tailwind loss. Avoid it.

Thunderstorms - Stages? What is needed to form?

Avoidance distance?

Is FIS-B datalink weather good enough for tactical avoidance?

→ Cumulus, Mature, Dissipating

→ Unstable lapse rate + Uplifting Force+ Moisture.

→ Avoid severe thunderstorms by at least 20 miles

→ FIS-B (ADS-B In) images can be 5–15 minutes old. Use it for strategic decisions (route selection), not threading between cells.

You inadvertently enter a thunderstorm. What do you do? (AIM 7-1-27)

• Eyes on instruments; don't look outside (lightning) • Plan a course through the storm in minimum time; don't turn back once inside • Pitot heat on; penetrate below the freezing level or above the −15°C level to avoid the worst icing • Disengage autopilot altitude/speed hold • Hold a constant attitude, not altitude. Ride the waves. [UPDATED]

What is structural icing and when does it occur?

→ An accumulation of rime, clear or mixed ice on the airframe.

→ Requires visible moisture and a temperature at or below 0°C (32°F).

What are the structural icing intensity levels?

→ Trace: becomes noticeable, less than ¼ in/hr

→ Light: ¼–1 in/hr; occasional deicing; problem if prolonged

→ Moderate: 1–3 in/hr; frequent deicing; exit ASAP

→ Severe: more than 3 in/hr; ice protection can't keep up; exit immediately

Icing hazards by cloud type and the escape for each?

→ Stratus: wide layers, low water content, icing layers rarely thicker than 3,000'. Climb or descend out.

→ Cumuliform: high water content but icing is brief. Deviate around.

→ Freezing rain: supercooled by falling through cold air. Climb to the warm layer above.

→ Freezing drizzle: no warm layer assumed. Climb, descend or turn out of the area.

Scenario - You inadvertently encounter icing.

What do you do?

Does deice/anti-ice equipment make it legal?

→ Leave visible moisture; move to an altitude above freezing (climb, descend or turn)

→ Anti-ice/deice equipment does not mean the airplane is approved for flight in icing (FIKI). Check the POH.

How do you use a pneumatic deicing system (boots)?

→ Activate at the first sign of ice; don't wait

→ Some residual ice stays between cycles; it increases as speed/temperature drop

→ May take several cycles before ice sheds

Roll Upset - What is a Roll Upset?

What are the signs?

How do you recover?

(AC 91-74)

What:

An uncommanded roll from ice separating airflow over the ailerons/outer wing.

Signs:

Ailerons deflecting on their own; yoke feels lighter or heavier. Hand-fly in icing.

Recovery:

→ Lower AOA, roll wings level

→ Set power, watch airspeed before adding back pressure

→ Don't retract flaps unless the wings are confirmed ice-free (retracting raises AOA)

FIKI aircraft should be aware of the aircraft's certification icing envelope.

How does approach/landing configuration change with ice accumulated?

→ Gear extension plus ice means extra drag

→ Deploy flaps in stages; watch the aircraft's response. If anything is abnormal, don't add more (consider retracting).

→ Higher approach speed; longer runway if available; carry power in the flare

→ Brake sparingly; watch for skidding

What are some steps to know when preparing to descend through known icing in a non-FIKI aircraft?

Advise ATC; declare an emergency if needed

→ Carb heat, windshield and pitot heat on

→ Stay above the clouds as long as possible

→ Keep a clean configuration as long as possible

→ Propeller to max RPM to keep ice off the blades (constant-speed props only, not the 172)

Scenario - During climb you hear small ice pellets hitting the airplane.

Are you in danger?

The pellets themselves aren't the hazard.

They mean freezing rain or SLD (supercooled large drops) aloft, which would be extremely hazardous. Get out.

Your induction air filter is blocked by ice. How will you know, and what protects you?

Signs

→ Loss of power (RPM drop, rough running)

Protection

→ Alternate induction air (172S: alternate air door; see POH)

→ Fuel-injected engine: no carburetor, so no carb ice, but induction icing can still block intake air.

What is precipitation static (P-static) and its effects?

A static charge that builds as the airplane flies through rain, snow, ice crystals, dust or volcanic ash, then discharges.

Effects:

→ radio noise, possible complete loss of VHF comms, degraded nav, inaccurate magnetic compass readings.

What do extreme cold and warm temperatures do to the altimeter?

Cold: air shrinks pressure columns.

→ indicated altitude reads higher than true.

→ You're physically lower than you think.

Warm: columns expand.

→ indicated altitude reads lower than true.

→ You're higher than you think.

Explain "High to Low, Look Out Below."

Flying from high to low pressure (or warm to cold) without updating the altimeter: it reads higher than your true altitude, so you fly lower than you should.

Why do baro-VNAV approaches have temperature limits?

Why is extreme cold dangerous?

Baro-VNAV builds its glidepath from barometric altitude.

→ In cold air, true altitude is lower than indicated, so the airplane flies a lower physical path than designed, eroding obstacle and terrain clearance without the pilot knowing.

→ Plates list the limits (e.g., "LNAV/VNAV NA below −15°C").

What does IMSAFE stand for?

Pre-flight self-assessment.

→ Illness: any symptoms?

→ Medication: prescription or OTC drugs?

→ Stress: psychological pressure?

→ Alcohol: within 8 hours, 0.04%?

→ Fatigue: enough rest?

→ Emotion: emotionally upset?

What is PAVE?

A method to identify and manage risk.

→ Pilot (IMSAFE)

→ Aircraft (condition, W&B)

→ enVironment (airport conditions, weather)

→ External pressures (delays, alternates, schedules)

What is the 3P model?

Perceive, Process, Perform.

What is the DECIDE model?

A continuous decision-making loop.

→ Detect a change

→ Estimate the need to counter it

→ Identify needed actions

→ Choose the actions

→ Do the actions

→ Evaluate afterward

Define ADM, hazard, and risk.

ADM: a mental process to consistently determine the best course of action for a set of circumstances.

Hazard: a present condition that could lead to an accident.

Risk: the future impact of a hazard that isn't controlled or eliminated.

What are the 5 hazardous attitudes and their antidotes?

Anti-authority ("don't tell me") → follow the rules

Impulsivity ("do it quickly") → think first

Invulnerability ("won't happen to me") → it could happen to me

Macho ("I can do it") → taking chances is foolish

Resignation ("what's the use") → I can make a difference

What resources and skills does Single-Pilot Resource Management (SRM) use?

Resources: dispatchers, weather briefers, maintenance, ATC.

Six skills: CFIT awareness, ADM, risk management, automation management, task management, situational awareness.

What factors cause most CFIT accidents?

→ Lack of situational awareness

→ Failure to comply with minimum safe altitudes

→ Insufficient planning

What is hypoxia, and what are the supplemental oxygen requirements?

Hypoxia = lack of oxygen.

→ 12,500–14,000' MSL: crew needs O2 if there more than 30 min.

→ Above 14,000': crew needs O2 at all times

→ Above 15,000': O2 offered to every passenger.

What are the common illusions?

Inversion

Coriolis

Elevator

False horizon

Leans

Autokinesis

Graveyard spiral/spin

Somatogravic

Climbing out in the clouds: look outside or at instruments?

Why?

→ At the instruments.

→ Looking outside in IMC can cause spatial disorientation.

Can you get in trouble taking off into IMC in uncontrolled airspace without a clearance?

Yes.

Technically permitted by 91.173, but the NTSB has ruled it careless/reckless (91.13), and pilots have been violated for it.

What are the three fundamental skills of instrument flying?

What are the three common cross-check errors?

Skills: instrument cross-check, instrument interpretation, aircraft control.

Cross-Check Errors:

→ Fixation: full concentration on one instrument.

→ Omission: leaving an instrument out of the scan.

→ Emphasis: relying on one instrument instead of a combination.

What is attitude instrument flying, and what are the two methods?

Controlling the aircraft by reference to flight instruments only.

Methods:

→ Control & Performance

→ Primary & Supporting

Describe the Control & Performance method.

Set power and attitude with the control instruments, then monitor the performance instruments and adjust.

→ Control: power (tachometer), attitude (attitude indicator)

→ Performance, pitch: altimeter, airspeed, VSI

→ Performance, bank: heading indicator, turn coordinator, magnetic compass.

What is a Standard-Rate turn?

Bank-angle rule of thumb?

Standard-Rate Turn ≈ 3° per second: 360° in 2 minutes.

Bank angle ≈ TAS/10 + 5.

How do you know you're in a standard-rate turn on the turn coordinator and on the G1000?

→ Turn coordinator: wingtip on the bold (white) standard-rate index mark.

→ G1000: turn rate indicator (tick marks above the HSI).

inner tick = half standard rate, outer tick = standard rate

Must all turns be made at standard rate?

When do you use half standard rate?

→ Standard rate is the norm, not a requirement. In holding: 3°/sec.

→ Half standard rate: when passed the FAF or above FL240.

Unusual attitudes

How do you recover from nose-high and nose-low?

Why should you level the wings before raising your AOA?

What will you see on your PFD if you’re in an extreme pitch up/down attitude?

Nose-high: add power, lower the nose, level the wings.

Nose-low: reduce power, level the wings first, then raise the nose.

Why wings first: stall speed and G-load rise with bank; leveling first protects the structure and maximizes lift to stop the dive.

On the PFD, red chevrons appear at extreme pitch up or down.

How do you recover from a spin?

Power idle

Ailerons neutral

Rudder full opposite

Elevator forward

Which instruments use the pitot tube vs. the static port?

→ Pitot + static: airspeed indicator.

→ Static only: altimeter, VSI.

The altimeter and VSI are not connected to the pitot tube.

What errors affect the airspeed indicator?

Position: disturbed airflow at the pitot/static openings (worst at high AOA, flaps)

Compressibility: air packs into the pitot tube at high speed (180+ kt), reads high

Density: IAS doesn't correct for altitude/temperature; TAS ≈ +2% per 1,000' / Indicated → Calibrated (position) → Equivalent (compressibility) → True (density).

Pitot Tube Blockage:

What does the Airspeed indicator do?

Only the ASI is affected.

Ram air blocked, drain hole open: airspeed drops to zero.

Ram air and drain hole blocked: acts like an altimeter.

→ Rises in a climb

→ Falls in a descent

→ No change in level flight.

→ Fix: pitot heat on.

Static Port Blockage:

What happens to each instrument?

What's the fix?

Altimeter: frozen at the altitude where it blocked.

VSI: reads zero.

ASI: Opposite of a pitot blockage.

→ Reads low in a climb

→ Reads high in a descent (stall risk).

Fix: alternate static air (cabin pressure). Expect:

→ Altimeter + ASI to read slightly high.

→ VSI to show a momentary climb.

Steam gauges only: break the VSI glass.

Scenario - Climbing in IMC.

Altimeter + VSI show a climb + Airspeed is increasing.

What's wrong?

Pitot tube blockage (ram air and drain hole blocked).

→ Trapped pressure makes the ASI act like an altimeter.

→ Turn on pitot heat.

Scenario - Trace rime ice on the wings + Airspeed dropping toward stall while descending.

What's wrong?

→ Pitot heat is off or failed.

→ Full pitot blockage (ice) = the ASI acts like an altimeter (because pitot blockage).

→ If the static port is clear, the ASI shows an increase in a climb and a decrease in a descent.

What errors is the Altimeter subject to?

Maximum allowable error?

Mechanical: instrument defects (calibration, friction, linkage)

Inherent: nonstandard temperature or pressure (high to low, warm to cold).

Maximum allowable error: Ground check: within 75' of field elevation with the current setting.

Does changing the Kollsman window affect the altitude ATC sees?

No.

→ The Kollsman window only changes the pilot's display.

→ The transponder sends pressure altitude (29.92); ATC's computer corrects it.