Aviation Navigation and Altimetry Fundamentals: Key Concepts

Aviation Fundamentals: Altimetry and Airspeed

Altimeter Settings and Altitude Measurement

The altimeter uses various pressure settings to determine altitude:

• QNH: The barometric pressure adjusted to sea level.
• QFE: If the altimeter is set to QFE and the aircraft is on the ground at the runway threshold, the reading will be zero altitude.

Calibration Settings and Flight Levels

What is false when using the QNH calibration setting in the altimeter?

Flight levels are used instead of altitudes.

What is true when using the STD calibration setting in the altimeter?

The indicated altitude is not the real altitude.

How are cruise altitudes usually given when using the STD altimeter setting?

In flight levels.

Which statement is false about barometer-based altimeter calibration?

The QNH setting assumes 1013 hPa and 15°C at sea level. (This assumption is characteristic of the Standard Atmosphere setting, not QNH.)

The imaginary line used to change the altimeter setting from STD to QNH is called...

The Transition Level.

Speed Measurement and Air Data

What parameter is measured with a simple Pitot tube?

Total pressure.

What is IAS (Indicated Airspeed)?

IAS is the raw estimation derived from the pitot-static tube reading.

TAS (True Airspeed) corrects indicated speed for which factors?

• Instrument installation error
• Compressibility
• Density

Radio Navigation and Positioning Systems

Ground-Based Navigation Aids (VOR, DME, ILS)

Which radionavigation aids provide azimuthal guidance with directional information?

VOR and ILS.

Which navigation aid does not provide azimuthal guidance?

DME (Distance Measuring Equipment).

Which system gives the angle referred to true north between the aircraft and a ground station?

VOR (VHF Omnidirectional Range).

What is the typical accuracy of VOR?

Approximately 1.4°.

Which system gives the distance between the aircraft and a ground station which is interrogated by the transponder?

DME.

Which navigation system allows a safe landing by giving the relative position of an aircraft to the glideslope and runway axis?

ILS (Instrument Landing System).

Global Navigation and Autonomous Systems

Which of the following is not a GNSS (Global Navigation Satellite System)?

NDB (Non-Directional Beacon).

What is the typical accuracy of GPS?

Up to 20 meters.

What does an SBAS augmentation system require?

Satellite-based and ground-based extra facilities.

Which autonomous navigation system uses accelerometers and gyroscopes to determine the aircraft's position?

INS (Inertial Navigation System).

What is true about an INS?

It must be initially aligned/calibrated.

Radar Systems

Which statement is true about radars?

A Secondary Surveillance Radar needs data communication with the aircraft.