Quiz: See How Well You Know Your Flight Instruments With These 6 Questions

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Being in IMC is the last place you want to be when your instruments start to act up...

1) You are flying in a Cessna 172 equipped with steam gauge instruments. You are being vectored by ATC in IMC coming into Madison, WI (KMSN). You are on a heading of 090 when ATC tells you to maintain best forward airspeed. You increase the engine RPM to accelerate to a faster airspeed. As you accelerate, you notice your heading indicator is indicating 090 but your magnetic compass is indicating a turn to the left. What is happening?

In the northern hemisphere, on easterly and westerly headings, aircraft accelerations will give you an error that indicates a turn to the north and decelerations will give an error of a turn to the south.

In the northern hemisphere, on easterly and westerly headings, aircraft accelerations will give you an error that indicates a turn to the north and decelerations will give an error of a turn to the south.
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2) Your airspeed indicator uses two different ports on the aircraft in order to accurately show airspeed. The pitot tube connects to the __________ and supplies dynamic pressure as well as __________ pressure. The static port connects to the __________ and supplies static pressure.

The pitot tube supplies both dynamic (ram air) and static pressure to the diaphragm and the static port supplies static pressure to the casing. Since the two static pressures oppose each other, they cancel out, leaving you with just dynamic pressure or ram air pressure, measured as indicated airspeed.

The pitot tube supplies both dynamic (ram air) and static pressure to the diaphragm and the static port supplies static pressure to the casing. Since the two static pressures oppose each other, they cancel out, leaving you with just dynamic pressure or ram air pressure, measured as indicated airspeed.
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3) ATC says "Cessna 236ES, Madison tower, winds are 360 at 10, runway 36 line up and wait." You scan your instruments and you notice your heading indicator and magnetic compass are both showing 360. After departure, you turn on course to Dubuque, IA (KDBQ). You notice that in straight and level, unaccelerated flight, your heading indicator and magnetic compass are off by 10 degrees. Which instrument is reading inaccurately? Why? What can you do to prevent this?

Just like any gyroscopic instrument, the heading indicator has a tendency to precess over time. The severity of how much it precesses depends on a few factors but two big factors are the magnitude and frequency of banking. It is recommended that every 15 minutes you sync it with the magnetic compass.

Just like any gyroscopic instrument, the heading indicator has a tendency to precess over time. The severity of how much it precesses depends on a few factors but two big factors are the magnitude and frequency of banking. It is recommended that every 15 minutes you sync it with the magnetic compass.
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4) You are shooting the LOC BC to Runway 17R in Grand Forks, ND (KGFK) in IMC. ATC is currently vectoring you on a left base before turning you to intercept the LOC BC. ATC says "Cessna 236ES, you're 5 miles from MANZA, turn left heading 200, maintain 3,000' until established, cleared LOC BC runway 17R approach." As you are turning to intercept, you notice the localizer needle deflecting more and more off-scale (your plane is equipped with an HSI). You think your HSI might not be working correctly. What should you do?

View FAA Chart

When shooting a LOC BC approach, it is imperative that you tune the front course NOT the back course otherwise you will reverse sense.

When shooting a LOC BC approach, it is imperative that you tune the front course NOT the back course otherwise you will reverse sense.
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5) You're in a TBM 900 at FL250 equipped with DME and an IFR approved GPS (sadly, it is inoperative). You are tracking a victor airway eastbound and pass over a VOR/DME. Your DME reads 0 nm. Is there a problem? If so, what should you do?

If you fly directly over a VOR/DME at FL250, your DME readout should be closer to 4 nm, not 0 nm, because DME measures slant range. So, your DME is not working properly. FAR 91.205 states that you need the appropriate navigation equipment on board appropriate for the route to be flown. This regulation allows you to use DME or an approved IFR GPS for distance information above FL240. In this case, the GPS is inoperative and now, so is your DME! In this event, you must report the issue to ATC, but you are allowed to continue at and above FL240 as long as repairs can be made at the airport of intended landing.

If you fly directly over a VOR/DME at FL250, your DME readout should be closer to 4 nm, not 0 nm, because DME measures slant range. So, your DME is not working properly. FAR 91.205 states that you need the appropriate navigation equipment on board appropriate for the route to be flown. This regulation allows you to use DME or an approved IFR GPS for distance information above FL240. In this case, the GPS is inoperative and now, so is your DME! In this event, you must report the issue to ATC, but you are allowed to continue at and above FL240 as long as repairs can be made at the airport of intended landing.
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6) Your vertical speed indicator (VSI) tells you how fast your aircraft is climbing or descending. Just like the other pitot-static instruments, it uses air pressure. In a climb, air pressure in the __________ is slightly __________ than the pressure in the __________ due to __________.

The VSI is designed similar to other instruments, using static pressure for operation. What sets this instrument apart is the calibrated leak. If this wasn't an integral part of the instrument, the VSI needle would always read 0. As you climb, the pressure immediately decreases in the diaphragm. Since the calibrated leak doesn't allow air to escape the casing right away, the pressure inside the casing remains slightly higher, causing the diaphragm to shrink. The same process happens in descent but in reverse.

The VSI is designed similar to other instruments, using static pressure for operation. What sets this instrument apart is the calibrated leak. If this wasn't an integral part of the instrument, the VSI needle would always read 0. As you climb, the pressure immediately decreases in the diaphragm. Since the calibrated leak doesn't allow air to escape the casing right away, the pressure inside the casing remains slightly higher, causing the diaphragm to shrink. The same process happens in descent but in reverse.
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