Aero Academic
Aero Academic
Aviation uses many abbreviations and a mixture of measurement systems. Australian charts show elevations in feet, navigation distances in nautical miles and some visibility in kilometres or metres. The habit that prevents most errors is to name both the number and its reference before you use it.
Checked against: Australian conversion factors are standard mathematical constants; terminology checked against CASA licensing guidance, Airservices Australia AIP GEN 2.6 conversion tables and Bureau of Meteorology aviation weather guidance, as summarised in Aero Academic’s 27 October 2026 editorial brief; instructor review pending before publication.
| Abbreviation | Meaning |
|---|---|
| CASA | Civil Aviation Safety Authority, Australia’s civil aviation safety regulator |
| ARN | Aviation Reference Number used in CASA’s systems |
| RPL | Recreational Pilot Licence |
| PPL | Private Pilot Licence |
| CPL | Commercial Pilot Licence |
| ATPL | Air Transport Pilot Licence |
| DAME | Designated Aviation Medical Examiner |
| ASIC | Aviation Security Identification Card |
| AVID | Aviation Identification; not equivalent to an ASIC for security-controlled airport access |
| KDR | Knowledge Deficiency Report issued with some CASA exam results |
| PIC | Pilot in command, the pilot responsible for the safe conduct of the flight |
| Solo | In the ordinary student context, flight with the student as the sole occupant |
| Abbreviation | Meaning |
|---|---|
| AIP | Aeronautical Information Publication, which holds essential air-navigation information and procedures |
| ERSA | En Route Supplement Australia, part of the Australian aeronautical information package |
| GNSS / GPS | Global Navigation Satellite System / Global Positioning System |
| VFR / VHF / UTC | Visual Flight Rules / Very High Frequency / Coordinated Universal Time |
| METAR | A routine aerodrome weather report |
| SPECI | A special aerodrome weather report issued when relevant criteria are met |
| TAF | An aerodrome forecast |
| GAF | Graphical Area Forecast, an Australian aviation weather product |
| SIGMET | A significant-weather advisory |
| Term | What it refers to |
|---|---|
| AMSL | Above mean sea level; Australian chart elevations are in feet AMSL unless stated otherwise |
| QNH | A barometric pressure setting associated with altitude indication |
| QFE | A pressure setting associated with height above a specified reference datum |
| FL (flight level) | A pressure-based level referenced to the standard pressure datum, not a surveyed height above the ground |
| Convert | Calculation |
|---|---|
| Nautical miles to kilometres | Multiply by 1.852 |
| Kilometres to nautical miles | Divide by 1.852 |
| Knots to kilometres per hour | Multiply by 1.852 |
| Knots to miles per hour | Multiply by approximately 1.15078 |
| Feet to metres | Multiply by 0.3048 |
| Metres to feet | Divide by 0.3048 |
| Pounds to kilograms | Multiply by 0.45359237 |
| Kilograms to pounds | Divide by 0.45359237 |
| Litres of fuel to kilograms | Multiply by the fuel density in kg per litre, from your aircraft documentation |
| Minutes to decimal hours | Divide by 60 |
| Decimal hours to minutes | Multiply by 60 |
Aviation language is packed with abbreviations, and Australian pilots work with feet for height, nautical miles for distance, knots for speed, litres or kilograms for fuel and hectopascals for pressure. These are not the units of everyday life, and mixing them up is the commonest arithmetic mistake a beginner makes.
The cure is a habit: every time you meet a number, say what it measures and what it is measured from. Is the distance in nautical miles or kilometres? Is the height above ground level or above mean sea level? Is the speed through the air or over the ground? A number without its reference is only half an answer.
This guide gives you the vocabulary and the conversions, with worked examples labelled as hypothetical so that nobody mistakes them for aircraft data. For real operations always use the approved documents for your aircraft and the current Airservices Australia publications.
Table 1 collects the licensing and training abbreviations you will hear in your first weeks. Several are explained in more depth in our guides: the ARN, DAME, ASIC and AVID in the paperwork guide, and the KDR in the guide on reading a Knowledge Deficiency Report.
A regional warning: do not assume an abbreviation always means the same thing in Australia and the United States. A PPL, for example, is a Private Pilot Licence in Australia and is an informal shorthand for a private pilot certificate in the United States. Define every abbreviation the first time you use it in your own notes, and note which country it belongs to.
Table 2 lists the abbreviations that appear on charts and in weather and navigation documents. AIP and ERSA are Australian publications, and our ERSA guides explain how to read the entries. METAR, SPECI, TAF and GAF are weather products, and the Bureau of Meteorology’s aviation knowledge centre explains how each is built.
The Bureau explains the products, but flight-planning information for a real flight should come from the appropriate authorised briefing arrangements. Training exercises and real flights are different things, and the guide you are reading is for learning.
Table 3 shows the pressure and height references. AMSL means above mean sea level, and Australian chart elevations are given in feet AMSL unless the chart says otherwise. QNH is a pressure setting that makes an altimeter read altitude, QFE relates to height above a chosen reference datum, and a flight level is referenced to the standard pressure datum.
Do not present altitude, height and flight level as interchangeable labels. A surveyed height above the ground, an altitude above sea level and a pressure-based level can differ by hundreds of feet, and the differences matter for terrain clearance and for separation from other aircraft.
The international standard reference for a flight level is approximately 1013.2 hectopascals, and Australia uses hectopascals for altimeter settings.
Table 4 gives the conversions you will use most. They are mathematical constants, not aircraft performance data. A knot is one nautical mile per hour, and a nautical mile is exactly 1.852 kilometres, so never substitute a statute mile when you are working with nautical distances.
For Australian operational reference, Airservices directs pilots to the conversion tables in AIP GEN 2.6. Use those tables when you need an authoritative value, and use the factors here to build your understanding and check your work.
Write the units beside every number as you calculate, and cross them out as they cancel. It feels slow for a week and then it feels like a superpower.
Example (hypothetical): convert 25 nautical miles to kilometres. 25 × 1.852 = 46.3, so 25 NM is 46.3 km.
Example (hypothetical): convert 100 knots to kilometres per hour. 100 × 1.852 = 185.2, so 100 kt is 185.2 km/h.
Example (hypothetical): convert 2,000 feet to metres. 2,000 × 0.3048 = 609.6, so 2,000 ft is 609.6 m. These examples are unit conversions only. They do not change the units that an aircraft limitation, a chart or a clearance requires.
Australian fuel quantities are normally handled in litres, while aircraft weights are handled in kilograms. That means a fuel calculation often needs a volume to mass conversion before it can go into a weight and balance sum.
Mass equals volume multiplied by density. Always take the density from your aircraft’s own documentation, and remember that different fuels have different densities. A figure that is right for one fuel can be wrong for another.
Some older manuals and overseas documents quote fuel in other units. If you meet one, stop and confirm exactly which unit it is, because similar-sounding units can differ in size, and convert to litres before you do anything else.
Decimal hours are not clock notation. To convert 1 hour 30 minutes, add 30 ÷ 60 = 0.5 to the 1 hour, which gives 1.5 hours. To go the other way, convert 1.3 hours by multiplying 0.3 × 60 = 18 minutes. That makes 1.3 hours equal to 1 hour 18 minutes, not 1 hour 30 minutes.
Teach yourself this before you start using hourly fuel burn figures or logging decimal flight times, because the mistake is easy to make and the effect is a wrong fuel or time estimate.
The basic relationship is distance equals speed multiplied by time, with compatible units. Using knots and hours gives nautical miles. Rearranged, time in hours equals distance in nautical miles divided by groundspeed in knots.
Example (hypothetical): a leg is 60 NM and the planned groundspeed is 90 kt. 60 ÷ 90 = 2/3 hour, and 2/3 × 60 = 40 minutes. Use groundspeed, not airspeed, for this calculation, and do not substitute one for the other silently.
Example (hypothetical): assume a constant fuel flow of 18 litres per hour for that 40-minute leg. 18 × 40/60 = 12, so the simplified segment uses 12 litres. That is not a full fuel plan. It leaves out other phases of flight, contingencies, reserves and operational requirements.
Mass equals volume multiplied by density. Using an explicitly hypothetical density of 0.72 kg per litre, 40 litres has a mass of 40 × 0.72 = 28.8 kg. That is not an instruction to use 0.72 for every fuel or aircraft.
Before you accept any answer, run through the same short list. What quantity is being calculated? Which units are the inputs using? Are any conversions needed? Which reference datum applies? Is the result rounded sensibly? Does it make practical sense? Which approved document governs the real operation?
Pilots who ask those seven questions routinely catch errors before they matter. It is the same discipline in an exam room and in the cockpit.
When you are ready to practice, use the free E6B flight computer and the aviation calculators on this site, and check your answers against the factors in Table 4.
A nautical mile is exactly 1.852 kilometres. To convert nautical miles to kilometres, multiply by 1.852. To go back, divide by 1.852. A knot is one nautical mile per hour, so 100 knots is 185.2 kilometres per hour.
Altitude is measured above mean sea level, height is measured above a stated reference such as the ground, and a flight level is a pressure-based level referenced to the standard pressure datum. They are not interchangeable labels, and the differences can be hundreds of feet.
Australian aeronautical chart guidance uses feet for elevations, nautical miles for navigational distances and kilometres or metres for certain visibility information. Always read the legend of the chart in front of you rather than assuming every figure uses the same convention.
Fuel quantity is normally handled in litres, and aircraft weights in kilograms. To get from one to the other, multiply the volume in litres by the fuel density in kilograms per litre, taking the density from your aircraft documentation, because different fuels have different densities.
Multiply the decimal part by 60. For example, 1.3 hours is 1 hour plus 0.3 × 60 = 18 minutes, so 1 hour 18 minutes. Decimal hours are not clock notation, and treating 1.3 as 1 hour 30 minutes is a common mistake.
https://www.aeroacademic.com.au/guides/aviation-abbreviations-units-conversions