PILOT NAVIGATION

1. PILOT NAVIGATION Presentation Press F5 to start.

2. PILOT NAVIGATION Chapter 1 Units. Contents List. Click on a chapter. Chapter 2 Flight Planning. Chapter 3 Position Fixing. Chapter 4 Map Reading. Chapter 5 Weather. exit

3. PILOT NAVIGATION Chapter 1 Units Return to contents list exit

4. 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.

5. 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.

6. 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!

7. 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. 1000m 3300ft If the pilot takes no avoiding action the aircraft will hit the hill 1300 feet below the peak. 2000ft

8. 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.

9. 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’.

10. 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.

11. 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.

12. 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.

13. 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.

14. 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.

15. Pressure This table illustrates how the atmosphere thins with altitude: Altitude (feet) Air Pressure (millibars) Sea level1013 10,000 700 18.000 500 24.000 400 30,000 300 34,000250 39,000 200

16. Pressure Note 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 level1013 10,000 700 18.000 500 24.000 400 30,000 300 34,000250 39,000 200

17. Pressure The 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 level1013 10,000 700 18.000 500 24.000 400 30,000 300 34,000250 39,000 200

18. PILOT NAVIGATION Chapter 2 Flight Planning Return to contents list exit

19. The Triangle of Velocities Heading and True Airspeed (HDG/TAS) Windspeed and Direction (W/V) Track and Groundspeed (TK/GS)

20. The Triangle of Velocities Heading and True Airspeed (HDG/TAS) Windspeed and Direction (W/V) Drift is the angle between Heading and Track vectors Track and Groundspeed (TK/GS)

21. The Triangle of Velocities Heading and True Airspeed (HDG/TAS) Windspeed and Direction (W/V) Track and Groundspeed (TK/GS) Each vector has both a direction and a value (represented by the length of the arrow).

22. The Triangle of Velocities Heading and True Airspeed (HDG/TAS) Windspeed and Direction (W/V) Track and Groundspeed (TK/GS) Providing we have four of the elements of the vector triangle, we can find the other two.

23. The Triangle of Velocities Heading and True Airspeed (HDG/TAS) Windspeed and Direction (W/V) Track and Groundspeed (TK/GS) The quickest and most accurate way of solving the vector triangle is to use the Dalton DR Computer.

24. Flight Planning For private pilots and light military trainers, flight planning is carried out using the Pilot Navigation Log Card.

25. 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.

26. 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.

27. Flight Planning Temperature is required in order to calculate the True Airspeed (TAS) from the Calibrated Airspeed (CAS).

28. 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.

29. 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.

30. 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.

31. 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.

32. Safety Altitude If meteorological conditions deteriorate the pilot must always be prepared to climb above the safety altitude.

33. Air Traffic Control Flight Plan Before 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.

34. PILOT NAVIGATION Chapter 3 Position Fixing Return to contents list exit

35. 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).

36. 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.

37. 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.

38. 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.

39. 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.

40. 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.

41. 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. 

42. 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. 

43. 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.

44. 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.

45. 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.

46. PILOT NAVIGATION Chapter 4 Map Reading Return to contents list exit

47. 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.

48. 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.

49. Unique? The most important characteristic of a map reading feature is that it is unique and cannot be confused with any similar nearby features.

50. 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.