177 (Blackpool Airport) SQN. STAFF CADET TRAINING contents 1.1 units 1.2 fuel and pressure 1.3 exam style questions 2.1 the triangle of velocities and flight planning 2.2 other factors of planning 2.3 exam style questions 3.1 position fixing part 1 3.2 position fixing part 2 3.3 exam style questions 4.1 map reading 4.2 exam style questions 5.1 weather 5.2 TAFs and METARs 5.3 exam style questions 1.1 units
Vertical Distance and Speed KEY POINT
In aviation, vertical distance is mostly measured in feet, except in the former communist bloc countries such as Russia. The main complication with this is that maps, including the OS maps, are calibrated in metres. You can, therefore, imagine the danger if a navigator accidently reads the map in feet instead of metres (remember that 1m equals approximately 3.3ft)! As vertical distance is measured in feet or metres, the units of vertical speed are feet/metres per minute. Horizontal Distance and Speed Horizontal distance is normally measured in nautical miles with speed measured in nautical miles per hour (also known as knots). Meteorological Units Throughout most of the world, the MET Office has switched to metric units, but despite this, they must continue to use feet for altitude and knots for wind speed. You can imagine how confusing the navigator’s job would be if they didn’t! Aircraft Weight Once again, several different units are used across the world. In America, aircraft are measured in pounds and imperial ounces with most other countries using kilograms or metric tonnes. Questions
1. Which countries use metric units for vertical distance? 2. What units are used for horizontal distance and speed? 3. America uses pounds and imperial ounces for aircraft weight. What other units are often used? 1.2 fuel and pressure
Fuel We have to measure fuel by its volume because once the aircraft is airborne, we are no longer able to weigh it accurately. Different types of fuel have their own Specific Gravity (SI) which is a ratio of the weight of the fuel to the weight of the same volume of water. Conversion can be done on a calculator, a DR computer or on the chart in the RAF Flight Information Handbook. Pressure Pressure in the earth’s atmosphere is caused because of the weight of the air above it. As a result of this, at higher altitudes there is less pressure than at sea level. As a result, high‐
altitude aircraft have to be pressurised to provide enough oxygen for the crew to breathe. KEY POINT
Two main units are commonly used: inches of mercury (used in the US) and Millibars which is used in most other countries. Another unit that is rarely used is pounds per square inch. Questions
1. How do we measure aircraft fuel? 2. Why do high‐altitude aircraft have to be pressurised? 3. What are the main units of pressure? 1.3 exam style questions
1. Why must you be very careful if using an OS map to work out safety altitudes? A. The map does not cover a large enough area B. The map is out of date C. The elevations are un metres D. The grid is based on kilometre squares 2. Which units are used to measure pressure in the atmosphere throughout Europe? A. Millibars B. Inches of mercury C. Atmospheres D. Hectonewtons 3. In which 2 countries would you expect to be told by air traffic control to fly at a height of 300m instead of 1000ft? A. UK and Ireland B. Australia and New Zealand C. Russia and China D. USA and Mexico 4. If the fuel tanker has its fuel delivery gauges calibrated in different units from the receiver aircraft fuel gauges, what methods of conversion would the crew use? A. Any of the other three answer methods B. A DR computer C. A calculator D. A fuel weight and volume conversion chart 2.1 the triangle of velocities & flight planning
KEY POINT
When we have 4 out of the 6 components of the triangle we can solve it by a variety of methods including drawing a scaled diagram on graph paper of using a Dalton Reckoning Computer. Flight Planning The pilot plans the flight using the Pilot Navigation Card, dividing the route into a number of separate legs. Once all the information has been completed on the card, the triangle of velocities can be used to calculate: 1. What heading the aircraft must fly 2. What the groundspeed will be Questions
1. Make a copy of the triangle of velocities. 2. How many components of the triangle are needed before it can be solved? 3. List the information that is included on the Pilot Navigation card. 2.2 other factors of planning
Fuel Planning We must always calculate the flying time to calculate how much fuel would be needed. If the answer is a complicated decimal, then we always round UP, otherwise too little fuel will be available. For example, an aircraft, consuming fuel at a rate of 12 gallons per hour, flies for 61.25 minutes would need 12.25 gallons of fuel, rounded up to 12.3 Safety Altitude KEY POINT
The calculation of the safety altitude at which the aircraft must fly is the navigator’s number one priority. To calculate the safety altitude we add 1000ft to the highest elevations on or near the intended track and ten round it to the nearest 100ft. E.g. if the highest elevation was 768ft, the safety altitude would be 1800ft. Air Traffic Control Flight Plan Aircraft crews always notify Air Traffic Control of their intentions so that overdue action can be taken if they do not arrive on time. Aircraft entering busy air space must also submit a flight plan so that the flight can be coordinated with the other air traffic. Questions
1. How much fuel will an aircraft need if it consumes it at a rate of 10 gallons per minute and flies for 12.34 minutes? 2. What is the navigator’s number one priority? 3. If the highest elevation in the area id 3567ft, what would be the safety altitude? 2.3 exam style questions
1. The Navigator’s number one priority is: A. Calculation of safety altitude B. Navigating with a sextant C. Keeping the a/c above safety speed D. Calculating a/c altitude in metres 2. If the highest obstacle near your track is 1750ft, what is your safety altitude? A. 3800ft B. 1800ft C. 2700ft D. 2800ft 3. As well as solving the triangle of velocities, what other information is logged on the Pilot Navigation log card? A. Time for each leg and aircraft registration B. Time for each leg and fuel required C. Amount of fuel received from tanker D. Met forecast of icing and thunderstorms 4. In the triangle of velocities, which vector represents the track and groundspeed? A. The longest one B. The shortest one C. The vector with two arrowheads D. The vector with one arrowhead 3.1 position fixing part 1
Visual Fixing When you identify a unique feature beneath the aircraft, this gives a visual fix known as a pinpoint that the pilot can use to determine his current position. Radio Aids This works in the same way as a portable radio. A dial in the aircraft shows the bearing from which a radio beacon is transmitting. If you know where the beacon is, a position line can be drawn on the chart along this bearing. If two other position lines are plotted, a 3 position line fix can be obtained, determining the aircraft’s location. VOR/DME and TACAN KEY POINT
TACAN is simply the military equivalent of VOR/DME and both provide a more modern method of gathering potion lines. They give the magnetic bearing from the beacon to the aircraft and the slant range of the aircraft from the beacon. Astro Navigation (i.e. using the stars) This method was used by the early pioneers of aviation, but is now only used in extreme emergencies. Questions
1. What does Radio fixing work in the same way as? 2. What is the difference between radio fixing and using VOR/DME and TACAN 3. Why do you think that astro navigation was only used in the early days of flight? 3.2 position fixing part 2
Radar Navigation – (active systems) This method was invented during the Second World War, but early versions were crude and the signal could be easily detected by the enemy. Nowadays, however, the systems are much more reliable and many pilots no longer have to worry about constantly changing frequencies to evade detection. Passive Systems This is the term used to describe equipment which doesn’t transmit put simply receive signals, such as those from GPS satellites. Long Range Fixing These systems work by measuring the time that it takes for 2 synchronised signals to arrive from 2 different transmitting stations. KEY POINT
The Omega system was the first to provide worldwide coverage, but this is recently being replaced by GPS. Questions
1. What was the major problem with early Radar navigation systems? 2. What is meant by the term “passive system”? 3. What is the Omega system currently being replaced with? 3.3 exam style questions
1. Both VOR/DME and TACAN give the same information, is it: A. Magnetic track and groundspeed B. Airway centreline and distance C. Magnetic bearing and range to beacon D. True heading and range to the beacon 2. The radio compass works on the same principle as which of these equipments? A. A small portable radio B. A gyro magnetic compass C. A radio 1 transmitter D. A radio sonar buoy 3. The civilian equivalent of TACAN is known as: A. VOR/DME B. OMEGA C. LORAN D. ADF 4. All long range nav aids work on a similar basis, what do the equipments use to calculate position? A. Time interval between successive fixes B. Old moore’s almanac C. Phase difference on various radials D. Time interval between synchronised signals 4.1 map reading
Map reading is an essential skill for all aviators because all decisions taken in the air have to be taken extremely quickly, whereas there is more time to think on the ground. The Importance of the Aircraft’s Altitude The altitude of the aircraft is an important factor in determining which ground features to choose to help with navigation. At low level you must choose features with vertical extent, whereas at a higher level larger features with the necessary contrast to stand out from their background are needed. Contrast, Colour and Season The most natural features to use in map reading are rivers and coastlines because they have the greatest contrast and colour change between themselves and the land. Furthermore, during the winter months snow eliminates many features and renders features such as roads and railways useless. Choosing a suitable map... When choosing a map the most important thing is to make sure that the map is up to date, as many features will change drastically over time. For low speed flight smaller scale maps are used because more detail of the area is needed. For high speed flight, however, maps with larger scales are used as it dramatically reduces the number of map sheets required. Questions
1. Why is map reading so much harder in the air? 2. What types of features would be the best choice for low level aircraft? 3. Why can snow be such a problem for navigation? 4.2 exam style questions
1. What is the main difference between map reading on the ground and in the air? A. You do not need waterproof maps in the air B. There is no time in the air to discuss where we are C. The scale of maps is so different D. You don’t have to wear an oxygen mask on the ground 2. In the early stages of training, students are made to concentrate on which method of navigation? A. Map reading B. Air plot C. Mechanical track plot D. Astro navigation 3. When choosing natural (rather than man‐made) features for map reading, what characteristic is most important? A. Their size B. Their contrast and colour C. How they are shown on the map D. Whether they are frozen or not 4. What is the essential requirement of a feature for use in low level map reading? A. It must be a different colour from the background B. It must have vertical extent C. It must be large enough to be seen at high speed D. It must be a water feature 5.1 weather
Water in the Atmosphere The major variable in the atmosphere is water. A certain amount of air can only hold so much water vapour. If the same volume of air becomes cooler it will not be able to hold as much moisture and, eventually, it will reduce its dew point (when it becomes saturated with water vapour). At this temperature, dew will form on the ground or mist or fog may form. Clouds are formed when air is forced to rise for one of four reasons: 1.
2.
3.
4.
Turbulence Convection Orographic uplift Frontal uplift As air rises it cools and condenses, eventually reaching its dew point at which point the base of the cloud base is formed. Thunderstorms There are 5 main hazards associated with thunderstorms: 1.
2.
3.
4.
5.
Icing Precipitation – The most common is hail which can damage airframes. Severe turbulence – This can, in extreme cases, destroy aircraft. Lightning and Thunder – Creates fear but does not do that much damage. Landing Hazards – Flooded runways and refuelling dangers. KEY POINT
As a result of all these dangers, the best thing is for aircraft to avoid thunderstorms by a wide margin. Questions
1. What are the four factors that cause air to rise? 2. What are the five main hazards associated with thunderstorms? 3. What is the best course of action to take with thunderstorms? 5.2 TAFs and METARs
TAF = Terminal Aerodrome Forecast = Forecast These are usually published for a nine hour period. The first four figures of the code represent the period for which the TAF is valid: E.g. 0615 = Valid from 0600 hrs to 1500hrs. TAFs also give information on changes expected during the forecast period: ‐ BECMG (becoming) ‐ TEMPO (temporary) ‐ PROB (probability) E.g PROB30TS = 30% chance of a thunderstorm METAR = Meteorological Actual Report A METAR is recorded hourly and gives information about the current conditions at an airfield. If the weather is changing rapidly, however, a SPECI (special) report may also be issued in the same format. KEY POINT
TAFs are a type of weather forecast whereas METARs actually give information on the current weather conditions at a particular airfield. Questions
1. What is the difference between a TAF and a METAR? 2. Decipher the following TAF: 0716 PROB70TS BECMGRA= (RA = rain) 5.3 exam style questions
1. How does the met office pass information about airfield weather to aircrew? A. By TELEVISION B. By TEMPOs and BECMGS C. By RADAR D. By using TAFs and METARs 2. Which of the following is not one of the hazards to a/c that is found in thunderstorms? A. ISOBARS B. LIGHTNING C. ICING D. TURBULENCE 3. What are clouds made of? A. Visible droplets of water B. Steam C. Water vapour D. Scotch mist 4. The base level of clouds is normally the point at which the rising air has cooled to what temperature? A. 0oC B. Its dew point C. Its condensation D. 0oF