Vertical position and pressure
7 min readWritten fromR.K. Bali, chapter 2, pp. 10-13 and 30-32
A level is the general name for an aircraft's vertical position. The precise word matters because it tells the listener which datum is being used.
| Term | What it is measured from | Practical meaning |
|---|
| Height | A stated datum | Vertical distance from the specified reference, often an aerodrome or threshold. |
| Altitude | Mean sea level | Vertical distance of a point, object or level above MSL. |
| Elevation | Mean sea level | Vertical distance of a point or feature fixed on the earth's surface above MSL. |
| Flight level | 1013.2 hPa pressure datum | A constant-pressure surface identified by a flight-level number. |
Pressure Q-codes
| Code | Meaning | What the altimeter indicates |
|---|
| QFE | Pressure at the aerodrome elevation or runway threshold. | Zero at that reference point. |
| QNH | Altimeter setting for elevation above mean sea level. | Aerodrome elevation when on the ground. |
| QFF | Pressure reduced to mean sea level for meteorological use. | It is a weather pressure, not the normal flight setting. |
| QNE | Standard pressure setting: 1013.2 hPa. | A pressure altitude, expressed as a flight level; used where the sub-scale cannot be set below about 950 hPa. |
Keep the datum in the answerQNH gives an elevation on the ground. QFE gives zero at the aerodrome reference. Do not treat either as the standard flight-level setting.
Interactive Altimeter reference
ReferenceQFE
At the aerodromeReads zero
Airspace, FIRs and location indicators
8 min readWritten fromR.K. Bali, chapter 2, pp. 10-11 and 17-20
Airspace terms describe both the service and the space in which it is provided. Location indicators then give a short, internationally usable identity to an aeronautical station.
| Term | Meaning |
|---|
| FIR | A Flight Information Region: the airspace in which flight information and alerting services are provided. |
| Control zone (CTR) | Controlled airspace from the surface to an upper limit. |
| Control area (CTA) | Controlled airspace extending upward from a specified lower limit. |
| Terminal control area (TMA) | A control area normally established where routes converge near one or more major aerodromes. |
| Aerodrome traffic zone (ATZ) | Defined airspace around an aerodrome for protection of aerodrome traffic. |
| P, R and D areas | Prohibited, restricted and danger areas. The letter is followed by the FIR designator and a number. |
Indian FIR and indicator scheme
India has five FIRs: Delhi, Mumbai, Kolkata, Chennai and Guwahati. ICAO location indicators use four letters: the first identifies the routing area, the second identifies the state or country, and the last two identify the place or station. In India the first letter is V.
| Indian code pattern | FIR / area | Example location indicator |
|---|
| VI | Delhi FIR | VIDP - Delhi |
| VA | Mumbai FIR | VABB - Mumbai |
| VE | Kolkata FIR; also Guwahati FIR in this allocation | VECC - Kolkata |
| VO | Chennai FIR | VOMM - Chennai |
On charts, an NDB normally has two or three capital letters, a VOR three, an ILS four, an aerodrome four and a significant point five letters including two vowels. Route designators combine a letter and a number; domestic Indian routes begin with W.
NOTAM: what changed, and for whom?
A NOTAM is time-critical telecommunication information about an aeronautical facility, service, procedure or hazard. N is a new NOTAM, R replaces one, and C cancels one. Series A covers internationally significant changes; B has limited international distribution; C is mainly domestic; D concerns defence-controlled aerodromes; and G is general, lasting operational information. Series numbering restarts at 0001 at 0000 UTC on 1 January. A PIB assembles current operationally significant NOTAM information before flight. AIRAC is the advance-notification system for significant changes on common effective dates. SNOWTAM is the special-series notice for hazardous snow, ice, slush or standing water; ASHTAM is the special-series notice for volcanic activity or ash of significance to flight.
Read the whole identifierFor a P, R or D area, the FIR letters and number are part of its identity. For a NOTAM, the series and action letter change the meaning.
Interactive Build an Indian location indicator
IndicatorVIDP
MeaningV + I + DP
Abbreviations: how to say them
6 min readWritten fromR.K. Bali, chapter 2, pp. 22-41
An abbreviation is not automatically spoken letter by letter. The publication separates terms that are spoken as words from those transmitted as individual letters, and standard phonetics remain available whenever spelling must be made unambiguous.
| How it is transmitted | Examples from the chapter | Use it when |
|---|
| As spoken words | ACARS, RNAV, METAR, SPECI, TAF, SIGMET, VOLMET, NOSIG | The term has a recognised spoken form in radiotelephony. |
| Individual letters, non-phonetic form | ILS, VOR, ATC, ATD, ATA, CB, DME, ETA, IFR, VFR, VHF, UHF, UTC, RVR, RVSM | The listed abbreviation is to be said as its constituent letters. |
| ICAO phonetic alphabet | For example, Victor Oscar Romeo when individual characters must be unmistakable | A callsign, location, code or unclear letter group needs spelling clarity. |
Common use does not erase the rule
Some widely used terms are heard as complete words in routine aviation speech, such as ILS, QNH and RVR. The safe habit is to learn the transmission form shown for the particular abbreviation, rather than making up a pronunciation from its spelling.
Useful groups to recognise
ATSAir traffic service
ATISAutomatic terminal information service
FIRFlight information region
The chapter's long abbreviation list is a reference vocabulary. For the test and the radio, learn the terms that identify a service, a flight state, a navigation aid, a weather report and a safety action.
Exam habitWhen asked how an abbreviation is spoken, answer the transmission method first, then give a sound example. Do not only expand the letters.
Bearings and aviation weather messages
8 min readWritten fromR.K. Bali, chapter 2, pp. 20-22 and 30-32
Q-codes condense a standard question and answer. Bearing codes must be read with their direction and reference: magnetic or true, and to or from the station.
| Code | What it tells you | Memory cue |
|---|
| QDM | Magnetic heading to a station in zero-wind conditions. | Magnetic, to the station. |
| QDR | Magnetic bearing from a station. | Magnetic radial out. |
| QTE | True bearing from a station. | True bearing out. |
| QUJ | True track required to reach a station. | True track in. |
| QGH | A controlled descent through cloud under direction-finding / homing procedure. | Descent guidance, not a bearing value. |
VOLMET and coded weather
VOLMET is a routine voice weather broadcast for aircraft in flight, carried on specified HF frequencies using single sideband (J3E) for listed aerodromes. The AIP publishes its callsign, frequency, hours and aerodrome group. Its content can include aerodrome identity, surface wind, visibility, RVR when applicable, weather, cloud, temperature, QNH and a trend. Broadcasts are in English; filler words such as “surface wind” are not spoken.
| Message | Purpose |
|---|
| METAR | Routine aerodrome weather report. |
| SPECI | Selected special aerodrome weather report issued when conditions require it. |
| TREND | Forecast of expected significant change over the next two hours, attached where applicable. |
| TAF | Aerodrome forecast. |
| ROFOR | Route forecast for a specified route or portion of it. |
Interactive Q-code lookup
CodeQDM
Plain meaningMagnetic heading to station
Do not merge report and forecastMETAR and SPECI report observed conditions. A TREND looks ahead for two hours; a TAF is the aerodrome forecast.
Complete code and abbreviation reference
15 min readWritten fromR.K. Bali, chapter 2, glossary and abbreviations
Remaining glossary terms
| Term | Meaning |
|---|
| Advisory Area and Advisory Route | Airspace or route where advisory service is available. |
| Aerodrome Control Service | ATC service for aerodrome traffic. |
| Aerodrome Traffic Zone | Airspace established around an aerodrome to protect aerodrome traffic. |
| Aeronautical Mobile Service | Mobile service between aeronautical stations and aircraft stations, or between aircraft stations. |
| Air-ground Communications | Two-way communications between aircraft and stations on the surface. |
| Air Traffic Control Clearance | Authorisation for an aircraft to proceed subject to stated conditions. |
| Clearance Limit | The point to which an aircraft is granted an ATC clearance. |
| Base Turn | A turn during the initial approach between the outbound and intermediate or final approach track. |
| Blind Transmission and Broadcast | A transmission without reply expected, and a transmission for general reception. |
| ACAS and CPDLC | Airborne Collision Avoidance System and Controller Pilot Data Link Communications. |
Q-code question and answer forms
| Code | Question form | Answer form |
|---|
| QDM | What magnetic heading should I steer to reach you, no wind? | Steer magnetic heading (number) degrees to reach the station. |
| QDR | What is my magnetic bearing from you? | Your magnetic bearing from the station is (number) degrees. |
| QTE | What is my true bearing from you? | Your true bearing from the station is (number) degrees. |
| QUJ | What true heading should I steer to reach you, no wind? | Steer true heading (number) degrees to reach the station. |
| QGH | May I make a homing flight? | You may home on the station using the stated procedure. |
| QDL | Can you give me a series of bearings? | A series of bearings or homing information is provided. |
| QFE, QNH, QNE and QFF | What is the pressure for the requested datum? | The requested pressure setting is supplied. |
| QSY | Shall I change to another frequency? | Change to the stated frequency. |
Abbreviations transmitted phonetically and Encode list
Words such as METAR, SPECI, TAF, VOLMET and ATIS are spoken in their prescribed forms. The Encode list is transmitted as individual non-phonetic letters: ATA, ATD, AFTN, ATC, ACC, QNH, QFE, ADS-B, ADS-C, ADF, CPDLC, UTC, CB, DME, ETA, ETD, FIR, FMS, GLS, GNSS, GPS, GCA, GPWS, HF, IFR, ILS, IMC, QDM, MLS, NTZ, NDB, NOZ, PAR, PDC, PSR, RPI, RVSM, RCP, RVR, SSR, TMA, UHF, UIR, VHF, VIP, VOR, VFR and VMC.
