Post on 24-Dec-2015
PILOT NAVIGATION
Presentation
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PILOT NAVIGATION
Contents List.
Click on a chapter.
Chapter 1 Units.
Chapter 2Flight Planning.
Chapter 3Position Fixing.
Chapter 4Map Reading.
Chapter 5Weather.
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PILOT NAVIGATION
Chapter 1
Units
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Units
Most countries still use feet to measure aircraft height and altitude. Only in Russia and China are you expected to fly and report altitude in metres.
Units
Most countries still use feet to measure aircraft height and altitude. Only in Russia and China are you expected to fly and report altitude in metres.
Units
Most countries still use feet to measure aircraft height and altitude. Only in Russia and China are you expected to fly and report altitude in metres.
Despite still using feet to measure aircraft altitude, most countries have adopted metres to show elevations on maps - the British OS map is an example.
Great care is needed because an aircraft being flown in thousands of feet can be in a very dangerous position if a navigator reads a mountain top as being 2000 feet instead of 2000 metres!
Safety Altitude
Imagine an aircraft is flying at 2000 feet above sea level towards a hill with a peak 1000 metres above sea level.
One metre is equal to 3.3 feet, so the 1000 metre peak is actually 3300 feet above sea level.
If the pilot takes no avoiding action the aircraft will hit the hill 1300 feet below the peak.
1000m
3300ft2000ft
Safety Altitude
The Navigators number one priority at all times is to calculate and ensure the aircraft is above the safety altitude for the area.
He will take great care to ensure that elevations taken from maps which have contours and spot heights in metres, are converted into feet.
Vertical Speed
Vertical speed is measured in ‘metres per minute’ in Russia and China.
The rest of the world measures vertical speed in ‘feet per minute’.
Meteorological Reports
Most countries except the USA use metric units for meteorological reports, for instance:
The USA still reports visibility in miles and feet.
The rest of the world reports visibility in kilometres and metres.
Aircraft and Fuel
American built aircraft measure fuel in pounds or imperial tons. Most others use kilogrammes (kgs) or metric tonnes.
Although it would be more correct to measure fuel by its mass, fuel cannot be weighed when an aircraft is airborne.
The alternative is to measure its volume.
Specific Gravity
Different fuels have different densities or ‘Specific Gravities’.Specific Gravity (SG) is the ratio between the weight of the fuel and the weight of the same volume of water.
Water has an SG of 1.0
Jet fuel typically has an SG of about 0.8
This means that a litre of jet fuel will weigh only 80% of the weight of a litre of water.
Fuel Conversion
Conversion of fuel weight to volume, or between the various types of units (pounds, gallons, litres etc) can be done in several ways.
A calculator can be used, or conversion charts in the RAF Flight Information Handbook.
Alternatively the crew could use a DR Computer.
Pressure
Atmospheric pressure is caused by the weight of air above us.
The higher we go, the less air there is above us.
Atmospheric pressure is greatest at sea level and reduces as we climb up through the atmosphere.
Pressure can be measured in pounds per square inch (psi), inches of mercury (the method used in the USA), or millibars.
Millibars are used everywhere outside the USA.
PressureThis table illustrates how the atmosphere thins with altitude:
Altitude (feet) Air Pressure (millibars)
Sea level 1013
10,000 700
18.000 500
24.000 400
30,000 300
34,000 250
39,000 200
PressureNote that at a typical airliner’s cruising altitude of 34,000 ft the air outside has only one quarter of the sea level pressure.
Altitude (feet) Air Pressure (millibars)
Sea level 1013
10,000 700
18.000 500
24.000 400
30,000 300
34,000 250
39,000 200
PressureThe amount of oxygen available is also only one quarter of that at sea level. The cabin pressurization system maintains the oxygen level for the passengers and crew.
Altitude (feet) Air Pressure (millibars)
Sea level 1013
10,000 700
18.000 500
24.000 400
30,000 300
34,000 250
39,000 200
PILOT NAVIGATION
Chapter 2
Flight Planning
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The Triangle of Velocities
Heading and True Airspeed (HDG/TAS)
Track and Groundspeed (TK/GS)
Windspeed and Direction (W/V)
The Triangle of Velocities
Heading and True Airspeed (HDG/TAS)
Track and Groundspeed (TK/GS)
Windspeed and Direction (W/V)Drift is the angle
between Heading and Track vectors
The Triangle of Velocities
Heading and True Airspeed (HDG/TAS)
Track and Groundspeed (TK/GS)
Windspeed and Direction (W/V)
Each vector has both a direction and a value (represented by the length of the arrow).
The Triangle of Velocities
Heading and True Airspeed (HDG/TAS)
Track and Groundspeed (TK/GS)
Windspeed and Direction (W/V)
Providing we have four of the elements of the vector triangle, we can find the other two.
The Triangle of Velocities
Heading and True Airspeed (HDG/TAS)
Track and Groundspeed (TK/GS)
Windspeed and Direction (W/V)
The quickest and most accurate way of solving the vector triangle is to use the Dalton DR Computer.
Flight Planning
For private pilots and light military trainers, flight planning is carried out using the Pilot Navigation Log Card.
Flight Planning
The Pilot Navigation Log Card is purely for use by the pilot, ensuring that he has all of the necessary details readily available in the cockpit, to complete the flight safely and accurately.
Flight Planning
The pilot must enter the important details on the log card for each leg.
He must measure the tracks from the map using a protractor and the distances with dividers.
Flight Planning
Temperature is required in order to calculate the True Airspeed (TAS) from the Calibrated Airspeed (CAS).
Fuel Planning
The time for each leg and the fuel required is also calculated and logged on the card.
Running out of fuel in a car is inconvenient, in an aircraft it is disastrous.
Fuel Planning
The timings on the log cards also help the pilots pass accurate estimates of time of arrival (ETA’s) at waypoints or destinations.
Safety Altitude
The safety altitude is calculated by adding 1000 feet to the highest elevations (mountains, TV masts etc) on or near the track and rounding up to the nearest 100 feet.
Safety Altitude
For instance, if the highest obstacle near the track is 1750 feet, the safety altitude is:
1750 + 1000 = 2750 ft.
Rounded up to the nearest 100 ft this becomes 2800 feet.
Safety Altitude
If meteorological conditions deteriorate the pilot must always be prepared to climb above the safety altitude.
Air Traffic Control Flight PlanBefore a pilot commences his flight he must submit an ATC Flight Plan so that ATC units along his route, and at his destination, have details of his intended flight.
The Flight Plan is faxed or electronically transmitted to all of the ATC Centres en-route.
The Flight Plan includes the aircraft callsign, type of aircraft, time and place of departure, speed and altitude, intended route and ETA at destination. It also includes safety information such as the numbers of people on board and the types and quantities of emergency equipment carried.
PILOT NAVIGATION
Chapter 3
Position Fixing
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Position Fixing
In the pioneering days of aviation, aircraft could not fly unless the pilot could see the ground, as map reading was the only way of navigating.
Great strides were made during World War II, but it was not until the 1970’s that world-wide coverage was achieved with a fixing aid known as Omega.
This has now been superseded by Satellite Navigation (SATNAV) and the Global Positioning System (GPS).
Visual Fixing
By using a map to positively identify a feature on the ground below, you are making a visual fix known as a pinpoint.
The pinpoint is still a very reliable way of fixing one’s position, particularly in the early days of training.
Radio Aids
The next time you listen to a small portable radio, try turning the radio through 360 degrees.
You will find that there are two points in the circle where reception is poor, and two points where reception is best. This is because the aerial is in the form of a horizontal bar.
Radio Aids
The Radio Direction Finder (or radio compass) works on the same principle to find the direction of the aircraft from a beacon.
By using lines from two further beacons, preferably at about 60 degrees from each other, a ‘three position line fix’ can be plotted to accurately locate the position of the aircraft.
VOR/DME and TACAN
A more modern method of position finding utilises VOR/DME (civilian) or TACAN (military) beacons.
Both give the same information, namely the magnetic bearing of the aircraft from the beacon and the range.
Astro Navigation
Astro navigation works on the principle of using a sextant to measure the angle of the sun or stars to determine position.
Perhaps the only advantage of astro navigation is that it cannot be jammed.
It has been superseded by GPS.
Radar Navigation
Airborne radar has been refined to such a stage that ground returns received by an aircraft ca be matched to a ‘computerised map’ enabling an accurate fix to be obtained simply at the press of a button.
The major disadvantage of this system is that the radar transmissions can be detected by the enemy.
Long Range Fixing
During the 1950s and 1960s a number of long range ‘area’ navigation systems were developed:Gee, Decca, Loran and Omega.
All worked to a similar principle – measuring the time it takes two synchronised signals to arrive from two different transmitting stations to give a fix.
Global Positioning System (GPS)
With airborne microcomputers and the network of Global Positioning Satellites it is now possible for even an unskilled operator to obtain fixes to within a few metres.
Active / Passive Systems
The development of radar-homing missiles has necessitated the development of even more sophisticated electronic warfare (EW) countermeasures.
Whilst electronic warfare measures can be taken to protect ‘active’ systems, another approach is to use only ‘passive’ systems.
‘Passive’ systems do not transmit, merely receiving signals such as those transmitted by GPS satellites. Combining these with a triple Inertial Navigation System (INS) will give a very accurate position fix.
Navigation Training
Despite the availability of accurate navigation systems a student pilot will spend a great deal of time, especially in the early stages of his training developing the basic skill of map reading.
PILOT NAVIGATION
Chapter 4
Map Reading
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Map Reading
You can make the same mistakes map reading in the air as on the ground, but with the extra mental pressure that there is no time when you are flying to have a discussion about your location.
Altitude
The best features to select for map reading will depend upon whether the aircraft is at high or low altitude.
At low level it is important to choose features which have vertical extent – chimneys, hills, power stations etc.
At high level vertical features cannot be seen and larger features are needed – lakes, woods, islands etc.
Unique?
The most important characteristic of a map reading feature is that it is unique and cannot be confused with any similar nearby features.
Contrast and Colour
Of the natural features used in map reading rivers and coastlines are generally the most useful.
They show the greatest contrast and colour change between themselves and the land.
Map Scales
Special maps are produced for map reading from the air.
Emphasis is placed on features more easily identified from the air.
They are normally made to a much smaller scale – typically 1:500,000
Timing Marks
Before embarking on a flight in an aircraft without sophisticated navigation aids, a student will put timing or distance marks along each of the legs of his route.
10 20 30 40
Timing Marks
If he loses his place along his track he need only consult his watch, work out the time since his last waypoint and that will tell him where to look at the map.
10 20 30 40
PILOT NAVIGATION
Chapter 5
Weather
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The Atmosphere
Pure air consists of 79% nitrogen, 20% oxygen and 1% other gases.
The major variable in the atmosphere that affects weather is water in all of it’s forms.
The air pressure at sea level is caused by the weight of the air above us. With increasing altitude the pressure reduces, and so does the temperature.
Water Vapour
Air holds water vapour as an invisible gas. The warmer the air, the more water vapour it can hold.
As air is cooled, its ability to hold water vapour is reduced. Eventually it becomes ‘saturated’ and can hold no more water vapour – this is the ‘dew point’.
If the air continues to be cooled below it’s ‘dew point’ then visible droplets of water start to form – dew, mist, fog or clouds.
Water Vapour
There are four ‘trigger actions’ which cause air to rise:
TurbulenceConvection - heatingOrographic Uplift - hills and mountainsFrontal Uplift - cold or occluded fronts In each case temperature and pressure fall until the ‘dew point’ is reached, and at that altitude the base of the cloud is formed. Cirrus (high level clouds) consist of ice crystals, but most clouds consist of tiny visible droplets of water.
Turbulence Convection Orographic Uplift Frontal Uplift
Turbulence Convection Orographic Uplift Frontal Uplift
Turbulence Convection Orographic Uplift Frontal Uplift
Turbulence Convection Orographic Uplift Frontal Uplift
Turbulence Convection Orographic Uplift Frontal Uplift
Turbulence Convection Orographic Uplift Frontal Uplift
Turbulence Convection Orographic Uplift Frontal Uplift
Thunderstorms
Thunderstorms present a variety of hazards to an aircraft.
Thunderstorms
Thunderstorms present a variety of hazards to an aircraft. They are best avoided by a large margin.
Some of these hazards are:Icing - airframe and enginePrecipitation - usually hailTurbulenceLightningSevere downdrafts
Thunderstorms
Modern aircraft carry weather radar to assist in avoiding thunderstorms.
Thunderstorms
The amount of lift produced by a wing significantly reduced as ice accumulates. The stalling speed is also increased.
ThunderstormsThis ice accumulated on a wing leading edge during flight.
The pilot was fortunate to land safely.
ThunderstormsThorough de-icing prior to flight is vital.
Thunderstorms
The importance of avoiding thunderstorms is illustrated inthe following photographs. They are of a BaxGlobal plane that took off from Calgary, Canada and encountered hail.
The pilot managed to return and land at the Calgary airport.
This damage was inflicted upon the plane within 5 minutes of take off.
Thunderstorms
Thunderstorms
Thunderstorms
Thunderstorms
Thunderstorms
Thunderstorms
Thunderstorms
Thunderstorms
Thunderstorms
Two Asiana Airlines' pilots were awarded citations for safely landing their aircraft damaged by hailstones. There were 200 passengers on board.
Lightning strikes on aircraft do not normally cause major damage. This strike damage on the nose of a NOAA Hercules is typical.
Heavy rain can flood runways and reduce wheel braking effectiveness. This is known as aquaplaning.
Heavy rain can flood runways and reduce wheel braking effectiveness. This is known as aquaplaning.
Heavy rain can flood runways and reduce wheel braking effectiveness. This is known as aquaplaning.
Heavy rain can flood runways and reduce wheel braking effectiveness. This is known as aquaplaning.
Aquaplaning video
Landing at this US airport would not be recommended!
Landing at this US airport would not be recommended!
Isobars
Isobars join points of equal pressure (just as contours join all points of equal height) and help meteorologists and pilots understand how the air is moving.
Isobars
Isobars join points of equal pressure (just as contours join all points of equal height) and help meteorologists and pilots understand how the air is moving.
In the northern hemisphere air circulates clockwise around anticyclones (high pressure areas). HH
Isobars
Isobars join points of equal pressure (just as contours join all points of equal height) and help meteorologists and pilots understand how the air is moving.
And circulates anticlockwise around cyclones (low pressure areas). LL
Isobars
Isobars join points of equal pressure (just as contours join all points of equal height) and help meteorologists and pilots understand how the air is moving.
The easy way to remember this is that if you stand with your back to the wind the Low pressure is on your Left.
LL
Isobars
Isobar patterns represent the wind at 2000 ft above the surface.
The direction of the lines gives the direction of the wind and the closer the lines are together the stronger the wind
Low
Isobars
On the surface the wind will be about 25% less strong than at 2000 ft due to the effects of friction.
It will also have ‘backed’ about 25 degrees compared with the 2000 ft wind.
Low
Isobars
For instance, if the 2000 ft wind is 270/20
the surface wind will be 245/15
Low
TAFs and METARs
Weather information is passed from the met office to aircrew in the form of Terminal Area Forecasts (TAFs) and Meteorological Actual Reports (METARs).
Standard codes are used for brevity, for instance ‘CAVOK’ means that there is no cloud below 5000 feet and visibility is at least 10 km. (Cloud And Visibility OK)
TAF and METAR Decodes
BR MistDZ DrizzleHZ HazeFU SmokeRA Rain
FZ Freezing TS ThunderstormsFG FogSH ShowerSN Snow
- Slight + Heavy
The codes can be used in combination e.g. + RASH means heavy rain showers.
PILOT NAVIGATION
The End
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PILOT NAVIGATION
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