Instrument Flashcards
Explain how an altimeter works?
An altimeter is designed to measure static pressure
It relates to an indicated altitude.
As the aircraft climb, the static pressure in the instrument case will decrease, allowing the capsule to
expand and moves the needle to the correct altitude. For a descent the opposite applies.
Altimeter are calibrated to ISA.
Errors are PIM BLT (Baro, Lag, Temperature)
Explain how a VSI works?
The VSI measures the rate of change of static pressure and displays this as a rate of climb or descent.
The capsule is fed with static pressure and reacts to any change, whereas the static pressure feed into the case is restricted by a metering unit creating a differential static pressure between the capsule and the case.
Explain how an ASI works?
The ASI measures dynamic pressure as:
The difference between the total pitot pressure measured in the instrument’s capsule and the static pressure measured in the case.
The dynamic pressure represents the IAS on the instrument. Errors of the ASI are PIM.
What is glass cockpit?
Cockpit that features electronic flight instrument displays.
Large LCD screens rather than the analog instrumentation.
What information does a mode S transponder transmit?
= Sierra Mode
- Altitude (25ft increment)
- 24 bits code transmit to Secondary Surveillance Radar
- Registration
- Sqwak code
- GS
ADS-B (Doesn’t need SSR anymore) It’s transmit its information auto
- IAS
- GPS position or INS position
- Magnetic Heading
- Altitude
- Vertical Speed
- Selected Target Altitude (ADS-B V2
What is TCAS?
Traffic Collision Avoidance System
This system can determine the track and
closing speed of other aircraft fitted with transponders and determines if a collision is possible
It provides visual and aural warnings as well as a command actions and how to avoid the collision.
This is done with vertical avoidance command only.
TA: Traffic Advisory (3,3 nm – 40s)
RA: Resolution Advisory (2,1 nm – 25s)
What are NDB/ADF errors?
Interference from other NDB stations, thunderstorms, night effect, coastal refraction, mountain effect.
A NDB must maintain a minimum accuracy of 10°.
What happens with the ASI if the pitot probe is blocked during the climb/the descent?
PUDSOD, Pitot Blocked Underead in descent, Static Blocked Underead in the climb.
What is the difference between IAS and TAS?
TAS = True Air Speed and is the only speed.
It’s the IAS (Indicated Airspeed) corrected for Position, Instrument and Manoeuvre error, but also for compressibility effect and density.
What is LSS?
LSS = Local Speed of Sound.
It’s calculated by 38.95 * sqrt (T° in K). At sea level
LSS=660kts.
What is GPWS/EGPWS?
Ground Proximity Warning System
Central computer that receives various data inputs:
- Configuration
- Altitude
- ILS Glide slope deviation
- Radioaltimeter.
Detec if any of the following dangerous circumstances exist:
- Excessive rate of descent,
- Terrain closure
- Height or loss after take-off,
- Flaps or gear not selected for landing.
- Probable windshear aural and visual warnings
EGPWS is a GPSW with its own terrain database and able to detect predictive terrain closure.
