4.5.1 Weather and NOTAM check Area forecast We are planning to depart Oxford for Tottenham around 1400 hrs AEST time on April 30 (0400 UTC) which allows nearly four hours flight time before last light at Tottenham. Shortly before departure time we check the latest area 22 ARFOR briefing material downloaded from Airservices Australia's NAIPS Internet Service. AREA 22 AREA FORECAST AMEND OVERVIEW: FINE APART FROM ISOLATED SHOWERS IN FAR NORTHEAST TILL 11Z. WIND: 2000 5000 7000 10000 14000 18500 070/10 VRB/10 VRB/15 240/15 ZERO 220/15 MS06 210/20 MS15 CLOUD: SCT CU/SC 4500/9000,LOCALLY BKN IN NE TILL 11Z. AMEND WEATHER: SH IN NE. VISIBILITY: 6KM SH. FREEZING LEVEL: 10000 IN SE / 12000 IN NW. ICING: NIL. TURBULENCE: MOD IN CU. AREA QNH 03/07 NW OF YMIA/YMOR 1025, REST 1027 The first part is the general weather forecast for the area as a whole — this states the weather is expected to be fine during the forecast period with some showers in the north-east, which doesn't affect our flight plan region. The wind velocity at 2000 feet amsl will be 070/10 knots and at 5000 feet the speed is shown as 10 knots but the direction is 'variable'. Scattered cumulus and stratocumulus is expected to form with bases no lower than 4500 feet and tops no higher than 9000 feet. The freezing level will be at 10 000 feet so surface temperatures will be mild. The area QNH we will use is 1027 hPa. It looks like a perfect day for flying. Note that it is not mandatory for VFR aircraft to use the area QNH while en route. You may substitute the current local QNH of any aerodrome within 100 nm of the aircraft or, if the local QNH at the departure airfield is not known, you can just set the sub-scale so the altimeter reads the known airfield elevation. Aerodrome weather reports and forecasts If we now look at some actual weather reports [METARs] and the forecasts [TAFs] for airfields in or near our flight region, we can check whether there is any significant variation from the general area forecast. The METAR for our alternate airfield Condobolin, issued at 0300 UTC, reports surface wind velocity 130/7 knots. The TAF, issued two hours earlier at 0107 UTC, forecasts that during the period 0200–1400 UTC the surface wind will be 050/8 knots, the visibility will exceed 10 km (9999 m) and there may be scattered cloud with bases at 4500 feet. There is no weather report for our other alternate. The TAFs are for an area within 5 nm radius of the aerodrome. CONDOBOLIN (YCDO) METAR METAR YCDO 300300Z 13007KT //// 22/04 Q1024 RMK RF00.0/000.0 TAF TAF YCDO 300107Z 0214 05008KT 9999 SCT045 T 19 23 19 15 Q 1027 1025 1025 1026 Be aware that smoke from bushfires or autumn fuel reduction burns can drift over extensive areas and may totally conceal some, or all, landmark(s). Smoke may also dictate flight at a considerably greater altitude than planned and visibility degradation may not appear in the weather forecast. In summer it is advisable to check the state rural fire service website maps for the current fire status. Combined with the area wind forecast it will enable an estimate of the smoke drift. Similar precautions are applicable in the northern dry season. The METAR for Ivanhoe (which doesn't appear on the WAC section shown but is just a few miles west of Oxford) issued at 0300 UTC records a surface wind velocity 120/10 knots. The TAF issued earlier at 0109 UTC, forecasts that during the period 0200–1400 UTC the surface wind will be 080/8 knots, the ceiling and visibility will exceed VMC minima [CAVOK], and from 0800 UTC the wind will shift to 120/10 knots. IVANHOE (YIVO) METAR METAR YIVO 300300Z 12010KT //// 25/10 Q1022 RMK RF00.0/000.0 TAF TAF YIVO 300109Z 0214 08008KT CAVOK FM08 12010KT CAVOK T 24 26 22 19 Q 1024 1023 1023 1024 The METARs and TAFs confirm that, although there is some variation between observed winds and forecast winds. the area forecast is generally representative of the weather in the region we intend to operate. We should also check the 'big picture' — the latest mean sea level analysis or 'surface chart' — issued by the Bureau of Meteorology but which we can obtain from Airservices Australia's NAIPS Internet Service. That chart (below) shows a persistent and strong high pressure system located over south-eastern Australia, which is directing easterly airflows into area 22 and is responsible for the fine weather. The nearest frontal weather is affecting only the south-west corner of the continent. Surface chart I have added the red wind arrows to indicate the surface airflow around the high pressure system. It is the convention that each full barb on wind arrows represents an incremental 10 knots wind speed and a half barb represents 5 knots; thus the wind speeds shown are 25, 15 and 10 knots. (Note that a solid triangular barb on wind charts indicates 50 knots.) Area 22 is located where the 10 knot wind arrow is pointing. Please read the Aviation Meteorology Guide module dealing with southern hemisphere winds. The BoM's aviation weather services provide the latest synoptic surface analysis charts and national forecast charts; area forecasts, TAFs, aviation warnings and a great deal of other information. Wind and temperature forecast charts are available for various flight levels and various times up to 30 hours ahead. To find the wind and temperature charts expand 'aviation charts' and select 'wind and temperature'. The flight levels of interest to recreational pilots are FL050 [5000 feet] and FL100 [10000 feet], note the times are UTC. Using the Aerodrome Weather Information Service [AWIS] While airborne, a radio-equipped aircraft can usually obtain a report of actual weather conditions at the larger aerodromes — see 'Acquiring weather and other information in-flight'. If a mobile 'phone is carried the AWIS (if available) can be used to obtain surface wind and some other weather data. Choosing the cruising level The forecast vertical wind profile indicates there is no cruising altitude which is better suited for an easterly flight than any other. In section 3.5 we determined the lowest safe altitudes were 2000 feet on the first leg and 2500 feet on the others. Thus there is no reason not to plan our flight at the recommended VFR cruising level for an easterly heading (below) of 3500 feet; being below the cloud base it will avoid dodging around scattered clouds. We have to make an estimate of the wind at 3500 feet, which in these light wind conditions will be above the friction layer and, as wind tends to back with height (in the southern hemisphere), we will plan for a wind velocity at 3500 feet of 060/10 knots. Flights operating under the Visual Flight Rules [VFR] outside controlled air space must be operated at levels selected in accordance with the table below when at a height above 5000 feet AMSL, and should be operated at such levels when below 5000 feet whenever practicable. (The cruising levels for aircraft operating under Instrument Flight Rules (IFR) are 500 feet lower.) VFR cruising levels Magnetic tracks 000° to 179° 180° to 359° Cruising altitudes (area QNH) 1500 ft 2500 ft 3500 ft 4500 ft 5500 ft 6500 ft 7500 ft 8500 ft 9500 ft Operating in accordance with the cruising levels does improve safety but pilots should be aware that the risk of collision still exists. For example, consider an aircraft tracking 175°, while to the south another aircraft is tracking 005° at the same correct cruising level. Those two aircraft could well be on a collision course — you must maintain situation awareness throughout all stages of flight. Weather radar The Australian Bureau of Meteorology provides online 'real time' snapshots from about 50 weather radars around Australia. The snapshots are taken at about ten-minute intervals and cover a radius up to 256 km from the antenna. The last four snapshots are retained on the website and can be looped as a progressive image, thus providing an excellent presentation of precipitation and storm movement. Go to the aviation weather services page and select 'Weather Watch Radar Network'. While on the aviation weather services page also have a look at the latest 'Satellite imagery' of the cloud cover over Australia. NOTAM check A check of the NOTAM contained in the area 22 ARFOR briefing material reveals only three that are connected with our planned flight. These three state that the aerodromes are no longer licensed by the Civil Aviation Safety Authority, which is — in effect — a notification that advisory NOTAM aren't issued for those airfields. CONDOBOLIN (YCDO) AD From: 01 090316 To: PERM C0001/02 AD LICENSE WITHDRAWN LAKE CARGELLIGO (YLCG) AD From: 01 090319 To: PERM C0003/02 AD LICENSE WITHDRAWN TOTTENHAM (YTOT) AD From: 01 090317 To: PERM C0001/02 AD LICENSE WITHDRAWN 4.5.2 The set-heading point It is necessary to establish the geographic position, and the point in time, at which navigation will commence after take-off. This set-heading or set-course point should be pre-planned if possible and is usually dependent on the take-off direction, the initial heading and the local environment. If, for example, the take-off direction coincides roughly with the initial heading, and there is no environmental reason to make a turn after take-off, then the set-course point is the take-off point — or very shortly thereafter — and an en route climb technique will be used. However, if the take-off direction is opposite to the initial heading then it is usual to climb out on runway heading until well clear of the circuit area, and at circuit height, then continue climbing in a gentle turn — in the direction of the circuit — that will bring you back over the centre of the airfield, at a height not less than 2000 feet agl, to avoid any aircraft that may be overflying at 1500 feet to join the circuit. Refer to 'The standard circuit pattern'. The set-course point is then overhead the airfield and an en route climb may be indicated if the planned cruising altitude has not yet been reached. Another possibility is to choose an easily identifiable landmark well outside the circuit area as the set-course point. Whichever position is chosen, overhead the airfield or an external location, the flight plan should start from that point and the estimated time required to reach that point should be added to the take-off time allowance in the flight plan. 4.5.3 Heading, ground speed and fuel calculation We plan to cruise at 70 knots CAS and using the rule of thumb that TAS is 1.5% greater than CAS for each 1000 feet of altitude amsl we will increase CAS by 6% to arrive at a TAS of 75 knots at the planned cruising alttude of 3500 feet. That calculation (or perhaps 2% per 1000 feet) is near enough for navigation purposes but it is not actually correct; see the section on density altitude. To complete our flight plan we have to estimate the heading to fly, the ground speed, the flight time for each route segment and the fuel required. We will use the 1-in-60 arithmetic method outlined in section 4.2. Step 1: find the wind correction angle by estimating the angle at which the forecast wind meets the tracks, multiply the result by the wind speed and divide by the aircraft TAS. i.e. WCA = relative angle x wind speed / TAS (a) Segment 1: track = 094° true; w/v = 060/10 knots; relative angle = 34; TAS = 75 knots so WCA = 34 x 10 / 75 = 5°. (b) Segment 2: track = 061° true; w/v = 060/10 knots; relative angle = 1; TAS = 75 knots so WCA = 1 x 10 / 75 = 0°. (c) Segment 3: track = 040° true; w/v = 060/10 knots; relative angle = 20; TAS = 75 knots so WCA = 20 x 10 / 75 = 3°. Step 2: calculate the true heading, remembering that the wind correction is applied in the direction the wind is coming from; so that: (a) Segment 1: wind is from the left, correction angle is 5° and the heading is 094 minus 5 = 089° true. (b) Segment 2: wind is from dead ahead, correction angle is 0° and the heading is 061 plus/minus 0 = 061° true. (c) Segment 3: wind is from the right, correction angle is 3° and the heading is 040 plus 3 = 043° true. Step 3: convert the true headings to magnetic headings. There is an isogonal passing through the chart in the route planning module (the dashed purple line), which indicates the local variation is 10½°E. Applying that to our true bearing — remembering our aide-memoire "variation east, magnetic least" — and we have the following headings: 079°, 051° and 033° magnetic. Flight plan Route segment Distance Track (true) Heading (true) Heading (mag) Oxford – Warraway Mountain 74 094° 089° 079° Warraway – road junction 52 061° 061° 051° Road junction – Tottenham 33 040° 043° 033° Step 4: estimate the ground speed. Deduct the (acute) angle at which the wind meets the track from 115 (for angles up to 60°, use 105 for greater angles) and apply that as a percentage of the wind speed (to the maximum of 100%) subtract the result from TAS if wind coming from ahead to abeam, otherwise add; thus: (a) Segment 1: track = 094° w/v = 060/10 kn: angle = 34; 115 –34 = 81% of 10 = 8 kn headwind and ground speed = 67 knots. (b) Segment 2: track = 061° w/v = 060/10 kn: angle = 0; 115 –0 = 100% of 10 = 10 kn headwind and ground speed = 65 knots. (c) Segment 3: track = 040° w/v = 060/10 kn: angle =20; 115 –20 = 95% of 10 = 10 kn headwind and ground speed = 65 knots. Step 5: estimate the time interval for each leg dividing the distance by the ground speed and converting to minutes; thus: (a) Segment 1: distance = 74 nm; speed = 67 kn: 74/67 × 60 = 66 minutes. (b) Segment 2: distance = 52 nm; speed = 65 kn: 52/65 × 60 = 48 minutes. (c) Segment 3: distance = 33 nm; speed = 65 kn: 33/65 × 60 = 30 minutes. Sum the segment ETIs to produce the estimated time en route [ETE]: 144 minutes. Step 6: calculate the total fuel needed including: (a) The fuel consumed from start-up at the departure airfield to the set-heading point (10 minutes) (b) Extra fuel consumed in the climb (two minutes per 1000 feet = 6 minutes, refer to fuel planning) (c) The summed ETIs (144 minutes) (d) Fuel consumed in the circuit and landing at the destination airfield, including an allowance for delays in the circuit (10 minutes) (e) The fixed 45-minute reserve The total is 215 minutes — well within our full fuel endurance of 240 minutes and giving us 25 minutes margin on top of our fixed 45-minute reserve. We will use the fuel log during the flight. Fuel calculation and fuel log Cruise fuel flow: 16 litres/hr Usable fuel loaded: 64 litres Endurance: 240 mins Estimate Actual Airfield departure: 10 mins Climb penalty: 6 mins En route: Oxford – Warraway: 66 mins Warraway – road junction: 48 mins Road junction – Tottenham: 30 mins Estimated time en route: 144 mins Airfield arrival: 10 mins Fixed reserve: 45 mins Total fuel required: 215 mins Fuel margin (endurance–total required) 25 mins Completed flight plan Segment Altitude Distance Track (mag) Heading (mag) Ground speed ETI Comms Oxford – Warraway 3500 74 083° 079° 67 66 ML 124.9 Warraway – road junction 3500 52 050° 050° 65 48 ML 124.9 Road junction – Tottenham 3500 33 029° 031° 65 30 ML 123.9 QNH: 1027 Last light: 1755 hrs AEST Fuel margin: 25 mins 4.5.4 Marking the chart plot To assist in the in-flight calculations necessary to assess divergence from the required track, it is advisable to add drift lines to the plot and mark the halfway point on each segment. The drift lines are usually dashed lines drawn diverging 10° either side of track from the departure point or turning points, and converging 10° either side of track into turning points or the destination. It is also advisable to add distance marks to the track that roughly equate to ten minutes flight time, say 10 nm intervals for an ultralight. The distance marks can commence from the departure point/turning points or backwards from the turning points/destination, according to personal preference. Alternatively you may prefer to annotate the distance of particular landmarks along the track, from the set-course point or a turning point. Also mark at least one ground speed checkpoint on each segment, maybe 15–20 nm along the leg. A feature that crosses the required track more or less at right angles is quite handy, as the track made good is likely to differ from the track required. These chart markings are shown in the 'En route adjustments' module. The chart(s) and flight plan plus the means of keeping an in-flight log must, of course, be carried in the aircraft; a kneeboard is a handy device. The last part of our flight planning and preparation is to conduct a safety audit of our preparations (remember – Proper Preflight Planning Precludes Piss-poor Performance), but before going on to that I suggest you read a couple of articles contained in the online version of CASA's magazine Flight Safety Australia: ~ 'Visual flight in marginal weather' — July - August 1999 issue. ~ 'Low cloud - Pressing on?' — April 1999 issue. There are many articles of interest to recreational pilots in Flight Safety Australia. A categorised index of such material is available on this site. STRICT COPYRIGHT JOHN BRANDON AND RECREATIONAL FLYING (.com)
