Interpret MET information Flashcards
What period of validity must the aerodrome forecast have?
Pilot must ensure forecasts cover the period of flight and that aerodrome forecasts for destination and alternate nominated in flight plan are valid for a period of not less than 30 min before and 60 min after planned ETA
REF: AIP ENR 1.10, 1.2.4 – Forecasts
How are cloud bases determined for TAF / TAF3 and GAFs?
In aerodrome forecasts, cloud heights are given above aerodrome elevations. In other forecasts heights are expressed as a flight level or with reference to mean sea level.
REF: AIP GEN 3.5, 4.2 – Interpretation and use of forecasts
How are amounts of cloud indicated in reports and forecasts?
Indicated using the following abbreviations:
FEW = 1-2 OKTAS
SCT = 3-4 OKTAS
BKN = 5-7 OKTAS
OVC = 8 OKTAS
NSC = NIL SIGNIFICANT CLOUD
REF: http://www.bom.gov.au/aviation/data/education/taf.pdf
When CB and TCU clouds are listed as ISOL, OCNL, FRQ and EMBD in a non-aerodrome forecast each description indicates what?
- ISOL – ISOLATED for individual CB and/or TCU over an area with a maximum spatial coverage of up to 50%
- OCNL – OCCASIONAL for well-separated CBs and/or TCUs over an area with spatial coverage of 50-75%
- FRQ – FREQUENT for CBs and/or TCUs with little or no separation over an area with spatial coverage greater than 75%
- EMBD – EMBEDDED for embedded within cloud layers and can not be readily recognised.
REF: http://www.bom.gov.au/aviation/data/education/gaf.pdf
How many OKTAS of cloud would you expect when the forecast / report indicates FEW + SCT below the alternate minima?
FEW (1-2) + SCT (3-4) = BKN 5-7 OKTAS –> Need an alternate or holding fuel!
In determining requirements for alternate aerodromes, forecast amounts of clouds below the alternate minima are cumulative: FEW + FEW = SCT; FEW + SCT = BKN; SCT + SCT = BKN or OVC
REF: AIP ENR 1.1, 10.7.2.1 Weather conditions
What is a METAR?
METAR – MET AERODROME REPORT. Routine report issued at fixed times, hourly or half hourly, and are made available at pre-flight briefing or on request to aircraft in flight. METAR’s are issued as SPECI’s when meeting the SPECI criteria.
REF: AIP GEN 3.5, 3.1.1 - Meteorological Reports
What is a SPECI?
Speci are non-routine aerodrome weather reports, issued whenever weather conditions (one or more observed meteorological element) fluctuate about or below specified criteria significant to aviation.
REF: AIP GEN 3.5, 3.1.2 - Meteorological Reports
When will a SPECI be issued?
- Cloud: >SCT below an aerodrome’s highest alternate minimum cloud base or 1500ft, whichever is higher; or
- Visibility: below an aerodrome’s highest alternate minimum visibility or 5000m, whichever is greater; or
- Significant changes in Wind speed/direction/gusts, TEMP (>5ºC)or QNH (>2hPa); or
- Sig Weather: thunderstorm, moderate or heavy precipitation, freezing precipitation, dust storm, sandstorm, funnel cloud (tornado or waterspout), low drifting or blowing dust, sand or snow, freezing fog.
NOTE: There are differences in issue criteria at ‘staffed’ and ‘non-staffed’ stations
REF: http://www.bom.gov.au/aviation/data/education/metar-speci.pdf
TAF validity and issue intervals?
Q: TAF validity and issue intervals?
- TAF3 = CAT A or B (still adheres to TAF CAT below):
a. Where: Selected Aerodromes (i.e. Darwin, Perth)
b. Issue interval: 3 hourly
c. Validity: 18, 24 or 30 hrs as per CAT of TAF below - CAT A and B:
a. Where: International Aerodromes (CAT A, i.e. Darwin, Perth, Broome) or Large Aerdromes (CAT B, i.e. Jandakot, Karratha, Barrow Island, )
b. Issue interval: 6 hourly
c. Validity: 24 or 30 hrs (CAT A) or 12 or 18 hrs (CAT B) - CAT C:
a. Where: Medium Aerodromes (YTST, YPKU))
b. Issue interval: 6 hourly
c. Validity: 12 hrs - CAT D:
a. Where: Small Aerodromes (YPKT)
b. Issue interval: 6 or 12 hourly
c. Validity: 12 hrs
REF: AIP GEN 3.5 – 4.8 Aerodrome Forecasts
TAF coverage distance?
5nm radius from ARP.
(= 9.26km)
REF: AIP GEN 3.5 – 4.8 Aerodrome Forecasts
What do you have to do if a forecast has FM or BECOMG?
Enforce any ‘operational requirement’ for this permanent change, allowing for 30 min buffers either side of the change period.
REF: AIP ENR 1.1, 10.7.2.7 - Weather Conditions
Define the terms BECMG and WATIR?
BECMG – Becoming describes an irregular rate of change in weather. Weather conditions are expected to change during the given period of time.
WATIR – Weather and Terminal Information Reciter. Combines meteorological information with additional terminal information from the airport operator.
REF GEN 3.5, 9.1 – AWIS and WATIR & http://www.bom.gov.au/aviation/data/education/taf.pdf
Are there 30 min buffers applied to INTER and TEMPO? What is the limit for this, the buffer or the INTER/TEMPO operational holding requirement?
Yes, when additional holding fuel is required and the ETA of the aircraft at its destination or alternate falls within the period 30 minutes before the forecast commencement time to 30 minutes after the expected time of cessation of these deteriorations.
If the holding time required extends past 30 minutes after the forecast cessation of these deteriorations, the aircraft need only carry sufficient fuel to hold until 30 minutes after the forecast cessation time.
REF: AIP ENR 1.1, 10.7.2.8 - Weather Conditions
From which requirements does a TAF3 exempt you and when?
Only from the following requirements within the 1st 3hrs of the TAF3 validity (monitoring/issue period):
1. 30 min buffers;
2. PROB 30 or 40 TS and associated sev turb; or
3. PROB 30 or 40 weather phenomenon that reduce visibility below alternate minima (i.e. FOG, Mist, Dust, etc.)
REF: AIP ENR 1.1, 10.7.2.9 - Weather Conditions
Operations under the VFR at night must not be conducted unless the forecast indicates?
The flight can be conducted in VMC at not less than 1000ft above the highest obstacle within 10 nm either side of track, the published LSALT, MSA or pilot calculated LSALT as per Part 91 MOS
REF: Part 91.277 – Minimum Heights – VFR Flights At Night & OMA 8.1.7 - Determination of Operating Minima for VFR Flights Onshore and Over Water
