Air navigation part one introduction to the earth

This can be done by calculation or by Navigation Computer.

To obtain True Air Speed (TAS) from CAS you need to correct for air density changes caused by changes in temperature and altitude.

Thus an IAS of 118 kts with a correction on the calibration card of +2 kts would give a CAS of 120 kts.

IAS В± Pressure Error В± Instrument Error = CAS.

Once the two errors have been accounted for, we are left with Calibrated Air Speed (CAS), formerly known as Rectified Air Speed (RAS).

Both errors can be measured by testing the aircraft under controlled conditions and a calibration card with the combined errors is displayed in the cockpit next to the instrument.

Pressure Error previously known as position is caused by sensing incorrect values of static pressure due to the position of the static vents relative to the airflow around the aircraft.

Instrument error is caused by poor manufacturing tolerances when the instrument was built.

The reading on the ASI can be in error because of two errors, namely Pressure Error and Instrument Pressure.

The movement due to dynamic pressure is amplified and displayed on the instrument as Indicated Air Speed (IAS), reading in knots.The two static pressures cancel out and the diaphragm will move due to the dynamic pressure.In forward flight the pressure above the diaphragm will consist of Dynamic + Static.Dynamic Air Pressure is the pressure caused by forward motion of the aircraft.We use an instrument called an Air Speed Indicator (ASI).We cannot use a speedometer to record aircraft speed.For aircraft, the speed is a measure of:.The speed for cars, motorcycles and other land-based vehicles:.How would we calculate the distance between them?Д¬alculation N 51Вє 24вЂ™ First Latitude: Second Latitude: N 40Вє 29вЂ™ Subtracting gives: 10Вє 55вЂ™ To convert 10Вє 55вЂ™ into nautical miles: 10Вє multiply by 60 = 600 Add the 55вЂ™ = 655 nm.These two latitudes are N40вњў9вЂ™ and N51вњў4вЂ™ For example Torrejon airfield (near Madrid in Spain) is due south of RAF St Athan.If two places are on the same meridian then it is possible to calculate the distance between them rather than having to measure it.If you do not have any equipment, using the marks along the edge of any piece of paper.The starting point goes through Greenwich and is referred to as the: вЂњPrime MeridianвЂќ.When recording your position вЂ“ the line of Latitude must be given first.Lines of Longitude are sometimes referred to as MERIDIANS 1 degree of latitude (60 minutes) equals 60nmДЄs a complete circle is 360В° then 360 x 60 gives the circumference of the Earth as 21600 nm (approx 25000 statute miles).

One minute of latitude represents one nautical mile (nm).Latitude/Longitude grid divides the surface of the Earth into degrees and minutes.Know the hazards that weather presents to aviation.Understand the types of compass systems used for air navigation, how they work and their limitations.Understand the principles of the 1 in 60 rule.Understand the principles of vectors and the triangle of velocities to establish an aircraftвЂ™s track and ground speed.Be able to carry out calculations to determine aircraft distance, speed and time.LEARNING OUTCOMES On completion of this unit, you should: AIR NAVIGATION Part 1 Distance Speed & Time

Air navigation part one introduction to the earth