Aircraft Instrument Systems — FAA A&P Test Questions (ACS AM.II.H)
Aircraft instrument systems is one of the largest Airframe subject areas, and the written test leans on it heavily. You are asked which instruments run off the pitot-static system, what an altimeter actually senses, which gyroscopic property drives an attitude indicator versus a turn needle, and why a magnetic compass misreads during turns and speed changes. Almost every question is recall about how one instrument works or how it fails, so the payoff comes from learning each instrument's power source, its sensing element, and its characteristic error.
Written by the AMTprep editorial team · Published · Last reviewed
Written against the FAA primary sources cited at the foot of this page.
What ACS AM.II.H covers
This area follows the instrument material in FAA-H-8083-31 and splits into three groups. The pitot-static group comes first: the altimeter, airspeed indicator, and vertical speed indicator all use static pressure, but only the airspeed indicator also needs pitot ram pressure. The altimeter is an aneroid barometer that senses ambient static pressure and displays it as altitude, and the vertical speed indicator is a rate instrument built around a calibrated leak. Expect questions on blockages, such as a plugged pitot inlet or an iced static port, and on the alternate static source, which admits cabin air when the primary ports are blocked and typically makes the altimeter and airspeed indicator read slightly high in an unpressurized aircraft. Static system leak checks and altimeter tests follow 14 CFR Part 43, Appendix E.
The gyroscopic group is second. Rigidity in space keeps the attitude indicator's gyro fixed while the aircraft maneuvers around it, and precession is the property the turn needle and the heading indicator depend on. Know which instruments are vacuum-driven and which are electric, and what a low vacuum indication means.
The magnetic compass group is third, and it is where most candidates lose points. Magnetic dip, the vertical component of the Earth's field, causes the northerly and southerly turning errors and the acceleration errors. Deviation comes from the aircraft's own magnetic fields and is what you compensate for when you swing a compass and fill out the correction card. The rest of the area covers instrument range markings, case and panel installation, pressure and temperature instruments, and basic electronic display systems.
Where this sits on the test
ACS AM.II.H is tested on the FAA Airframe written test, one of 1,739 ACS-tagged questions in the Airframe bank. Every question tagged to this area carries a worked rationale and its FAA handbook reference, so you can drill the code itself rather than the whole test.
FAA handbook references
- FAA-H-8083-31
Three traps candidates fall into
- Candidates assume anything on the pitot-static system needs pitot pressure. Only the airspeed indicator uses ram air; the altimeter and the vertical speed indicator work on static pressure alone. That one fact answers several test questions, including every question about which instruments a blocked pitot line affects.
- Rigidity in space and precession get swapped. Rigidity is why an attitude indicator's gyro stays put while the airframe rolls and pitches around it. Precession, the tilting that results when a force is applied to a spinning rotor, is the property that makes the turn needle deflect.
- Variation and deviation are treated as the same error. Variation is the angular difference between true and magnetic north at a location, and no adjustment to the instrument removes it. Deviation is caused by ferrous metal and electrical fields in the aircraft itself, and swinging the compass is what corrects it.
50 free sample questions from ACS AM.II.H
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Which three flight instruments are operated by the pitot-static system?
Show the answer and explanation
Answer: Airspeed indicator, altimeter, and vertical speed indicator
Why: The pitot-static system supplies ram (pitot) and static pressure to the airspeed indicator, altimeter, and vertical speed indicator. The attitude indicator, heading indicator, and turn coordinator are gyroscopic, and the magnetic compass is self-contained, so none of those rely on pitot-static pressure.· FAA-H-8083-31 — Pitot-static systems
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The altimeter, airspeed indicator, and vertical speed indicator each receive static pressure, but which one also requires pitot (ram air) pressure?
Show the answer and explanation
Answer: The airspeed indicator
Why: The airspeed indicator measures the difference between ram (pitot) pressure and static pressure, so it is the only one of the three connected to the pitot line. The altimeter and vertical speed indicator use static pressure alone, which is why a blocked static port affects all three but a blocked pitot tube affects only the airspeed indicator.· FAA-H-8083-31 — Pitot-static instruments
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An aircraft altimeter measures aircraft altitude by sensing which of the following?
Show the answer and explanation
Answer: Ambient atmospheric (static) pressure
Why: An altimeter is an aneroid barometer that senses ambient static (atmospheric) pressure, which decreases with altitude. The difference between ram and static pressure is what the airspeed indicator senses, and the rate of change of static pressure is what the vertical speed indicator senses.· FAA-H-8083-31 — Altimeters
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What is the primary purpose of the alternate static source provided on many aircraft?
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Answer: To supply static pressure to the instruments if the primary static port becomes blocked
Why: An alternate static source gives the static instruments a backup source of static pressure if the primary external port becomes obstructed by ice or debris. It does not supply ram air, and moisture removal is handled by the system's drains, not the alternate static source.· FAA-H-8083-31 — Pitot-static system (alternate static source)
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Which gyroscopic property allows an attitude indicator's gyro to remain in a fixed position in space while the aircraft maneuvers around it?
Show the answer and explanation
Answer: Rigidity in space
Why: Rigidity in space is the gyroscopic property by which a spinning rotor maintains its plane of rotation relative to space, giving the attitude indicator a stable reference. Precession is the reaction of a gyro to an applied force, used by the turn instruments, and magnetic dip is a compass error, not a gyro property.· FAA-H-8083-31 — Gyroscopic instruments
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Which gyroscopic property is used in the operation of the turn-and-slip indicator (turn needle)?
Show the answer and explanation
Answer: Precession
Why: The turn needle relies on precession: as the aircraft yaws, a force is applied to the spinning gyro and the resulting precession deflects the needle in proportion to the rate of turn. Rigidity in space is the property used by the attitude and heading indicators, not the turn needle.· FAA-H-8083-31 — Gyroscopic instruments (turn indicators)
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The magnetic compass error that produces northerly and southerly turning errors is caused primarily by which characteristic of the Earth's magnetic field?
Show the answer and explanation
Answer: Magnetic dip near the magnetic poles
Why: Turning and acceleration errors of the magnetic compass result from magnetic dip, the tendency of the compass card to tilt as the field lines angle into the Earth near the poles. Variation is the angular difference between true and magnetic north, and deviation is local error from aircraft metal and electrical fields.· FAA-H-8083-31 — Magnetic compass
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When a magnetic compass is 'swung' and the compass correction card is filled out, what compass error is being compensated for?
Show the answer and explanation
Answer: Deviation caused by aircraft magnetic fields
Why: Compass swinging adjusts the compensating magnets and records residual deviation, the error caused by the aircraft's own magnetic and electrical fields. Variation is a charted geographic value not corrected by swinging, and dip-related turning errors are inherent to the instrument and cannot be removed by swinging.· FAA-H-8083-31 — Magnetic compass (compass swinging)
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An aircraft equipped only with an electric turn coordinator and otherwise air-driven (vacuum) gyro instruments loses the vacuum pump in flight. Which instrument would still be expected to operate normally?
Show the answer and explanation
Answer: The turn coordinator
Why: Because the turn coordinator in this setup is electrically driven, it continues operating when the vacuum pump fails. The attitude indicator and heading indicator are air-driven gyros that depend on the vacuum system, so both become unreliable once suction is lost. Splitting power sources this way provides redundancy.· FAA-H-8083-31 — Gyroscopic instrument power sources
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On an electronic horizontal situation indicator (EHSI), which group of formats is typically available to the pilot?
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Answer: VOR, map, plan, and weather radar.
Why: The EHSI is the navigation display of an electronic flight instrument system. It presents lateral navigation in selectable formats such as VOR, map, and plan, and it can overlay weather radar returns on the map. Engine thrust and raw ADF/NDB data are not the EHSI's defining navigation formats, so those choices are incorrect.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an electronic attitude director indicator (EADI), the moving runway symbol moves downward during the final stages of an approach. To recapture the correct profile, the aircraft must
Show the answer and explanation
Answer: fly down.
Why: On the EADI the moving runway symbol rises toward the aircraft symbol as the airplane descends correctly onto the glideslope. If the runway is moving downward, the airplane is high relative to the desired path, so the pilot must fly down to recapture the proper approach profile. Holding altitude or correcting laterally would not address a high vertical position.· FAA-H-8083-31 — Aircraft Instrument Systems
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During an instrument approach, the glideslope pointer deflects below the center mark. This indicates that the aircraft is positioned
Show the answer and explanation
Answer: above the glideslope.
Why: The glideslope pointer shows the position of the beam relative to the aircraft. When the pointer deflects below center, the glidepath is below the airplane, which means the airplane is above the glideslope and must descend. The localizer provides separate lateral guidance, so it is not the correct reference for a vertical deflection.· FAA-H-8083-31 — Aircraft Instrument Systems
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On a typical electronic flight instrument system (EFIS), engine parameters are normally displayed on the
Show the answer and explanation
Answer: engine indicating and crew alerting display (EICAS/ECAM).
Why: Engine parameters are presented by the engine indicating and crew alerting system (EICAS/ECAM), usually on a dedicated engine and warning display. The EHSI is the navigation display and the EADI is the attitude display, so neither presents engine data.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an attitude director indicator (ADI), which feature is fixed to the instrument case and serves as the reference datum?
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Answer: The miniature aircraft symbol.
Why: On an ADI the miniature aircraft symbol is fixed to the case as the datum, while the artificial horizon and pitch scale move behind it to display the aircraft's attitude. Because the horizon line and pitch bars move, they cannot be the fixed reference.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an EADI, the flight director command bars display
Show the answer and explanation
Answer: the required path with respect to the actual path.
Why: Flight director command bars compute the steering commands the pilot must follow, showing the required flight path relative to the aircraft's actual path. The pilot maneuvers to center the bars, so the bars indicate where the aircraft should go rather than simply reporting current heading.· FAA-H-8083-31 — Aircraft Instrument Systems
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Which electronic flight instrument display includes a rising runway symbol during an ILS approach?
Show the answer and explanation
Answer: Electronic attitude director indicator (EADI).
Why: The rising runway symbol appears on the electronic attitude director indicator (EADI) during an ILS approach, climbing toward the aircraft symbol as the airplane descends toward the runway. The EHSI is the navigation/plan display and the EICAS/ECAM shows systems and engine data, so neither carries this attitude-related cue.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an autopilot coupled to the radio navigation receivers, the guidance inputs used for approach and en-route tracking are
Show the answer and explanation
Answer: ILS and VOR.
Why: A radio-coupled autopilot steers the aircraft using radio navigation signals, taking the ILS (localizer and glideslope) for approach guidance and VOR for en-route tracking. ADF bearing data is not used to directly couple the autopilot for tracking and capture, so options that include ADF are incorrect.· FAA-H-8083-31 — Aircraft Instrument Systems
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An EFIS uses two control panels. What is their purpose?
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Answer: One selects the type of EFIS display, and the other selects the source of the information being displayed.
Why: An EFIS uses two panels: a display control panel to select the display format and modes, and a source-select (switching) panel to choose which symbol generator or sensor feeds the displays for redundancy. The other choices misdescribe the panels, since neither is merely a brightness control nor a single-panel arrangement with a passive backup.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an electronic flight instrument system (EFIS), which information is presented on the attitude director indicator (ADI/EADI)?
Show the answer and explanation
Answer: Flight director command bars, slip indicator, radio altitude, and autoland status.
Why: The attitude director indicator is the attitude display, so it presents flight director command bars, the slip/skid indicator, decision-height/radio-altitude data, and autoland/approach status. Magnetic heading, selected heading, waypoints, and weather radar are navigation-display items shown on the horizontal situation indicator (HSI/EHSI). See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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If the glideslope pointer on an instrument display is below the center mark, the aircraft is
Show the answer and explanation
Answer: above the glideslope.
Why: The glideslope pointer shows the position of the beam relative to the aircraft. With the pointer deflected below center, the beam is below the aircraft, meaning the aircraft is above the glideslope and must descend to intercept it. Localizer deflection is a separate lateral indication. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an EFIS installation, the weather radar return is normally displayed on the
Show the answer and explanation
Answer: horizontal situation indicator (navigation display).
Why: Weather radar returns are overlaid on the navigation display (horizontal situation indicator/EHSI), where they appear relative to the aircraft track in a plan view. The attitude director indicator is the attitude display and does not present a plan-view weather picture. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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The attitude director indicator (ADI) of an electronic flight instrument system primarily displays
Show the answer and explanation
Answer: pitch and roll attitude.
Why: The attitude director indicator is the attitude instrument, displaying aircraft pitch and roll against an artificial horizon. Waypoints, heading, and weather radar are navigation-display items shown on the horizontal situation indicator, so options listing those are incorrect. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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On a navigation display in weather radar mode, the most intense precipitation of a severe storm is shown as
Show the answer and explanation
Answer: red areas with black surrounds.
Why: Weather radar codes return intensity by color, with the heaviest precipitation of a severe cell shown in red; areas with no significant return appear black around it. Green denotes light returns, so a green or blue core would not represent the most severe cell. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an EICAS-equipped airplane during normal flight, the lower display normally presents
Show the answer and explanation
Answer: secondary engine parameters and system data.
Why: On an Engine Indicating and Crew Alerting System, the upper display carries primary engine indications and crew alert messages, while the lower display in normal flight shows secondary engine parameters and system data. The maintenance/synoptic format is selected separately and is not the routine in-flight content. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an EFIS installation, radio altitude is normally displayed on the
Show the answer and explanation
Answer: attitude director indicator.
Why: Radio altitude is part of the approach/attitude information presented on the attitude director indicator, where it supports the decision-height and autoland displays during an approach. The horizontal situation indicator is the navigation display and EICAS shows engine and system data, so neither is where radio altitude is normally read. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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On an EFIS attitude director indicator, in addition to pitch and roll, the display typically includes
Show the answer and explanation
Answer: autoland status, decision height, flight director bars, and slip indicator.
Why: As the attitude display, the ADI adds approach and guidance data to pitch and roll: autoland status, decision height, flight director command bars, and the slip indicator. The compass rose and heading data belong to the navigation display, so any option that includes a compass rose describes horizontal-situation-indicator content rather than the ADI. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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An electronic flight instrument display unit is made up of which of the following?
Show the answer and explanation
Answer: Mode control panel, raster and stroke generator display, microprocessor, and data inputs.
Why: An electronic flight instrument display is built from a mode/control panel for selections, a CRT or LCD driven by combined raster and stroke generation, a processor to format the picture, and the sensor data inputs. Items such as a separate air data computer or weather radar processor are sources that feed the system, not parts of the display unit itself. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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A basic electronic flight instrument system (EFIS) consists of
Show the answer and explanation
Answer: attitude director indicator, horizontal situation indicator, and symbol generators.
Why: A basic EFIS comprises the two display tubes — the attitude director indicator (attitude) and the horizontal situation indicator (navigation) — driven by symbol generators that build the images from sensor data. The mode control panel and radio/distance magnetic indicator are associated equipment rather than the core display-plus-generator set. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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On a color primary flight display/navigation display, ILS deviation and computed guidance are conventionally shown in
Show the answer and explanation
Answer: magenta.
Why: On a color glass-cockpit display, ILS deviation pointers and computed/selected guidance are shown in magenta, the convention used for commanded or selected navigation information. Green and red serve other purposes in the color coding, so they do not match the ILS guidance convention. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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A modern electronic horizontal situation indicator (navigation display) will display which of the following?
Show the answer and explanation
Answer: Waypoints, ILS steering information, distance-to-go, and magnetic heading.
Why: A modern horizontal situation indicator presents flight-plan waypoints, ILS steering information, distance-to-go, and magnetic heading in a plan/map format. The glideslope readout and flight director data are attitude-display items, so the option grouping those with the navigation display is incorrect. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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What does the abbreviation EFIS stand for?
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Answer: Electronic Flight Instrument System.
Why: EFIS stands for Electronic Flight Instrument System, the CRT/LCD-based replacement for traditional electromechanical attitude and navigation instruments. The other expansions referring to fire indication or flight information are not the accepted meaning of the abbreviation. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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What does the abbreviation EICAS stand for?
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Answer: Engine Indicating and Crew Alerting System.
Why: EICAS is the Engine Indicating and Crew Alerting System, used to display engine parameters and present crew alert messages on a glass-cockpit airplane. The other expansions mis-state the words and are therefore incorrect even though they sound similar. See FAA-H-8083-31, Aircraft Instrument Systems.· FAA-H-8083-31 — Aircraft Instrument Systems
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A fiber-optic data bus link in an aircraft digital system is capable of:
Show the answer and explanation
Answer: bidirectional data transfer
Why: Per FAA-H-8083-31, a fiber-optic data bus can carry light signals in either direction along the same fiber, making it capable of bidirectional data transfer. It is not limited to a single channel or to one direction only.· FAA-H-8083-31 — Aircraft Instrument Systems
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With respect to data transmission, the ARINC 629 data bus operates as a:
Show the answer and explanation
Answer: half-duplex bus
Why: Per FAA-H-8083-31, ARINC 629 is a half-duplex bus: terminals share a common medium and take turns transmitting and receiving rather than doing both at the same instant. Full-duplex operation would require simultaneous two-way transmission, which 629 does not provide.· FAA-H-8083-31 — Aircraft Instrument Systems
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The signal in an ARINC 629 data bus system is carried over:
Show the answer and explanation
Answer: a twisted pair of wires or fiber optics
Why: Per FAA-H-8083-31, ARINC 629 carries its signal on a single shared twisted pair of wires (or alternatively on fiber optics), which allows many terminals to share one transmission line. It does not use a separate wire pair or coaxial cable for each data source.· FAA-H-8083-31 — Aircraft Instrument Systems
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A serial ARINC 429 data bus transmits data words using:
Show the answer and explanation
Answer: time division multiplexing
Why: Per FAA-H-8083-31, a serial ARINC 429 link sends words one after another in sequence over a single pair, which is time division multiplexing. Frequency-division or wave-division techniques separate signals by frequency and are not used by the serial 429 bus.· FAA-H-8083-31 — Aircraft Instrument Systems
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One of the recognized numeric data formats used in the ARINC 429 data word is:
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Answer: BCD (binary coded decimal)
Why: Per FAA-H-8083-31, BCD (binary coded decimal) is one of the numeric data formats carried in the ARINC 429 word, alongside BNR. ISO is a character/alphanumeric standard and is not one of the core numeric data formats of the 429 word.· FAA-H-8083-31 — Aircraft Instrument Systems
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A group of data bits that are all transmitted at the same instant, each on its own line, is referred to as:
Show the answer and explanation
Answer: parallel data
Why: Per FAA-H-8083-31, when a group of bits is transmitted simultaneously, each on a separate line, that is parallel data. Serial transmission sends bits one at a time on a single line, and a sync signal is a timing pulse rather than a data group.· FAA-H-8083-31 — Aircraft Instrument Systems
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The ARINC 429 data bus transfers data using which encoding method?
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Answer: bipolar return-to-zero
Why: Per FAA-H-8083-31, ARINC 429 transfers data using bipolar return-to-zero encoding, in which each bit returns to a null (zero) level between high and low states. Manchester bi-phase is used by MIL-STD-1553, and plain non-return-to-zero lacks the null state that 429 uses.· FAA-H-8083-31 — Aircraft Instrument Systems
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Which of the following aircraft data buses is bidirectional?
Show the answer and explanation
Answer: ARINC 629
Why: Per FAA-H-8083-31, ARINC 629 is the bidirectional bus, allowing terminals both to transmit and receive on the shared line. ARINC 429 is unidirectional (single source to multiple sinks), so it is not bidirectional.· FAA-H-8083-31 — Aircraft Instrument Systems
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Data is transferred on the MIL-STD-1553B data bus using:
Show the answer and explanation
Answer: Manchester bi-phase encoding
Why: Per FAA-H-8083-31, MIL-STD-1553B transfers data using Manchester bi-phase encoding, in which each bit carries its own clock transition at mid-bit, giving self-clocking and good noise immunity. Plain or bipolar non-return-to-zero encodings lack this embedded clocking and are not used by 1553B.· FAA-H-8083-31 — Aircraft Instrument Systems
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The general arrangement of an ARINC 629 data bus installation includes the:
Show the answer and explanation
Answer: data bus cable, current-mode coupler, and stub cable
Why: Per FAA-H-8083-31, a typical ARINC 629 installation consists of the main data bus cable, a current-mode coupler that inductively links each terminal to the bus, and a stub cable connecting the coupler to the LRU. The coupling is inductive (current mode), not voltage mode.· FAA-H-8083-31 — Aircraft Instrument Systems
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A simplex data transmission system consists of:
Show the answer and explanation
Answer: one transmitter and one or more receivers
Why: Per FAA-H-8083-31, a simplex system provides one-way transmission from a single transmitter to one or more receivers, the same single-source, multiple-sink arrangement used by ARINC 429. Multiple transmitters into one receiver, or a controller/terminal pair, describe other topologies rather than simplex.· FAA-H-8083-31 — Aircraft Instrument Systems
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Because the ARINC 429 data bus is unidirectional, establishing a two-way (bidirectional) communications link between two units requires:
Show the answer and explanation
Answer: two separate data buses
Why: Per FAA-H-8083-31, ARINC 429 carries data in only one direction, so two-way communication between two units requires two separate buses, one for each direction of data flow. A single bus can carry data only one way, and four buses are more than the two actually needed.· FAA-H-8083-31 — Aircraft Instrument Systems
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A liquid crystal display (LCD) used in an electronic flight instrument must be driven by what type of voltage?
Show the answer and explanation
Answer: Alternating current (AC).
Why: Liquid crystal cells are driven with alternating current. A sustained DC voltage causes electrolytic deterioration of the liquid crystal material, so the cells are energized with an alternating voltage that keeps the average DC level at zero, preserving the display over its service life.· FAA-H-8083-31 — Aircraft Instrument Systems
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Under what condition does a light-emitting diode (LED) used as an instrument indicator produce light?
Show the answer and explanation
Answer: When it is forward biased.
Why: A light-emitting diode is a semiconductor PN junction that emits light only when it is forward biased, allowing current to flow so electrons and holes recombine and release photons. With no bias or with reverse bias, no recombination current flows and no light is produced.· FAA-H-8083-31 — Aircraft Instrument Systems
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How does the operation of a liquid crystal display (LCD) instrument behave at low ambient temperatures?
Show the answer and explanation
Answer: It is slower to update as the displayed data changes.
Why: At low temperatures the liquid crystal becomes more viscous, so the molecules realign more slowly when the drive field changes. The display therefore responds sluggishly and is slow to update, which is why many LCD instruments include heaters to maintain an acceptable response time in cold conditions.· FAA-H-8083-31 — Aircraft Instrument Systems
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What is a primary advantage of a liquid crystal display (LCD) over a light-emitting diode (LED) display in aircraft instruments?
Show the answer and explanation
Answer: It consumes less electrical current.
Why: An LCD only modulates existing light rather than generating it, so each cell draws very little current, whereas an LED must be driven hard enough to emit light directly. The main advantage of the LCD over the LED is therefore its much lower current consumption.· FAA-H-8083-31 — Aircraft Instrument Systems
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On a liquid crystal display (LCD), "submarining" is
Show the answer and explanation
Answer: the inability of some LCD screens to respond to fast-moving images on the display.
Why: Submarining is the smearing or temporary disappearance of a moving symbol on an LCD when the liquid crystal cannot switch states quickly enough to keep up with rapidly changing data. It is a response-time limitation of the LCD itself, not a CRT magnetism fault and not a panel manufacturing step.· FAA-H-8083-31 — Aircraft Instrument Systems
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In addition to managing navigation, thrust, and automatic routing, a flight management system (FMS) also provides
Show the answer and explanation
Answer: dedicated status and warning messages for its own operation.
Why: Besides managing navigation, thrust, and automatic routing, the FMS generates its own dedicated status messages and warnings relating to its operation and the flight plan. Terrain-clearance and takeoff/landing configuration warnings are produced by separate dedicated systems, such as the GPWS/TAWS and the configuration-warning system, not by the FMS.· FAA-H-8083-31 — Aircraft Instrument Systems
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The areas that share the most ground with AM.II.H — study them alongside it.
- Engine Instrument Systems (AM.III.D)
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Frequently asked questions
- What happens if the static port is blocked?
- With the static port blocked, the altimeter freezes at the altitude where the blockage occurred, the vertical speed indicator drops to zero and stays there, and the airspeed indicator becomes inaccurate, reading low in a climb and high in a descent. Opening the alternate static source restores a static reference from inside the cabin, usually with a small indication error that the flight manual lists.
- What is the difference between variation and deviation on a magnetic compass?
- Variation is the angle between true north and magnetic north at a given location; it changes with geography and is handled by the pilot using charts. Deviation is the error caused by the aircraft's own ferrous metal and electrical currents. A mechanic corrects deviation by swinging the compass, adjusting the compensating magnets, and recording the residual error on a compass correction card.
- How do you swing a magnetic compass?
- Position the aircraft on a compass rose away from steel structures, run the engines and switch on the electrical equipment normally used in flight, then align on north to adjust the north-south compensating screw and on east to adjust the east-west screw. Check south and west and remove half of any remaining error, then record readings every thirty degrees on a new correction card.
- Which flight instruments are gyroscopic?
- The attitude indicator, the heading indicator, and the turn-and-slip indicator or turn coordinator are the gyroscopic flight instruments. The attitude and heading indicators rely on rigidity in space, while the turn instruments rely on precession. Depending on the installation, the gyros are spun by an engine-driven vacuum or pressure pump, by a venturi on older aircraft, or electrically.
- Why does a magnetic compass show a turn when the aircraft accelerates?
- Acceleration error comes from magnetic dip. The compass card is weighted so that it hangs slightly tilted, and on an easterly or westerly heading a change in speed makes it swing. In the Northern Hemisphere, accelerating produces an indication of a turn toward north and decelerating an indication toward south. The error does not appear on north or south headings.
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- Cleaning and Corrosion Control
- Mathematics
- Regulations, Maintenance Forms, Records, and Publications
- Physics for Aviation
- Inspection Concepts and Techniques
- Human Factors
Airframe
- Metallic Structures
- Non-Metallic Structures
- Flight Controls
- Airframe Inspection
- Landing Gear Systems
- Hydraulic and Pneumatic Systems
- Environmental Systems
- Aircraft Instrument Systems
- Communications, Light Signals, and Runway Lighting Systems
- Aircraft Fuel Systems
- Aircraft Electrical Systems
- Ice and Rain Control Systems
- Airframe Fire Protection Systems
- Rotorcraft Fundamentals
- Water and Waste Systems
Powerplant
- Reciprocating Engines
- Turbine Engines
- Engine Inspection
- Engine Instrument Systems
- Engine Fire Protection Systems
- Engine Electrical Systems
- Engine Lubrication Systems
- Ignition and Starting Systems
- Engine Fuel and Fuel Metering Systems
- Reciprocating Engine Induction and Cooling Systems
- Turbine Engine Air Systems
- Engine Exhaust and Reverser Systems
- Propellers
Primary sources
Drill ACS AM.II.H inside the full Airframe bank
Adaptive engine, timed exam simulator, ACS-code remediation, and oral prep — everything you need to pass.