Met Services

Question 1

• What are METARs & how often are they Issued

Answer 1

• Routine aerodrome reports issued on the hour during the hours of an ATS unit. (Only Manual METARs at Milford Sound, OH & WP)
• Outside the hours of an ATS unit an Auto METAR MAY be available every half hour from an Automatic Weather Station

Question 2

• When is NCD used

Answer 2

• When there is No Cloud Detected below 10,000ft at AA, WN & CH, or at any other level for all other domestic aerodromes.

Question 3

• Define NSC

Answer 3

Additional terminioligy added to TAFs and TRENDS only at AA, WN & CH

• NSC = No Significant Cloud
  
  • No Sig Cloud & No CB or TCU observed
  • No cloud base below 5000ft or the highest minimum Sector altitude.
• AA = 5000ft
• WN = 6500ft
• CH = 7000ft

Question 4

• GS vs GR

Answer 4

• GS ( Small Hail) = Hailstones < 5mm in diameter
• GR (Hail) = Larger then 5mm

Question 5

• Define CAVOK

Answer 5

Additional terminioligy added to TAFs and TRENDS only at AA, WN & CH

• CAVOK = Ceiling and Visibility OK
• No Cloud with a base below Min Sector Alt:
  
  • AA = 5000ft
  • WN = 6500ft
  • CH = 7000ft
  • OR CB or TCU at any Height
• Visibility is 10km or Greater, and
• There is no significant weather

Question 6

• In the absence of any precipitation,
  
  • FG (Fog)
  • BR (Mist)
  • HZ (Haze)

are used whenever the visibility is less than..

Answer 6

• FG = < 1000m
• BR = 1000m - 5000m
• HZ = < 5000m and the reduction is caused by something other than water droplets or ice crystals.

Question 7

• When is Vis 9999 used?

Answer 7

• At AA, WN, & CH on the Auto METAR when the visibility is 10km or greater

Question 8

• VC (In the Vicinity) means:

Answer 8

• Within 8km - 16km of the aerodrome ref point.

Question 9

• What is a SPECI and who issues it.

Answer 9

• A SPECI is a special aerodrome report issued off the hour in METAR code.
• It is issured by the ATS unit. (Only available on Manual METARs (Milford Sound, OH & WP)

A SPECI will be issued immediatley after a deterioration in conditions but a SPECI reporting an improvement will only be issued once it has persisted for 10 minutes.

Question 10

• How long is a SPECI valid for?

Answer 10

• A SPECI is only valid until the issue of a new METAR (On the Hour)

Question 11

• How often are METAR AUTOs issued and who issues them?

Answer 11

• METAR AUTOs are issued every 30minutes by an Automatic Weather Station.

Question 12

• Can a METAR AUTO determine cloud type?
  (i. e. TCU and CB)

Answer 12

• No

It is indicated by /// on a METAR AUTO at the end of the cloud group.

Question 13

• Can RVR be reported on a METAR AUTO?

Answer 13

• Yes

(At AA & CH)

Question 14

• A TTL (TREND)
  
  • What is it?
  • Whats its Valitdity
  • Who issues it?

Answer 14

Trend Type Landing Forecast

• A TREND is a forecast of any significant changes that are expected to occur, appended to the bottom of aerodrome METAR AUTO reports at AA, WN & CH (OH & WP also)
• Validity:2 Hours and supersedes the TAF during this time.
• Issued by: The Metservice

Question 15

• RVR (Runway Visual Range)
  
  • Aerodromes that use it?
  • When is it used?

Answer 15

• Used at AA & CH when visibility reduces below 1500m

Measured at: Touchdown Zone (TDZ), Mid-Point (MID) & Stop-end (END)

TDZ only on METAR AUTOs

Question 16

• When are TAFs at Domestic aerodrome issued?
  
  • NZDT?

Answer 16

• Between:
  
  • 1430 - 1630 UTC
  • 2130 - 2215 UTC
  • 1400 - 1430 UTC (for a limited number of airports to meet overnight requirements)
• Issue times are advanced by 1 Hr during daylight savings.

Question 17

• When are TAFs issued at AA, WN & CH?
  
  • Validity?

Answer 17

• Within 1 hour before the start of the validity period of
  
  • 1200, 1800, 0000 and 0600 UTC
• Valid for 24 hours.

Question 18

• What is a ROFOR?

Answer 18

• A ROFOR is a Route Forcast which is issued in self-evident plain langauge form. The issue and validity periods are taylored to suit the individual aircraft operators.
• Winds are in ºTrue

Question 19

• Aircraft Reports (AIREPs)
  
  • When must they be made?

Answer 19

AIREPs are required to be made and transmitted by aircraft equipped with CPDLC at the compulory MET reporting points (regardless of the nature of the wx), and at other reporting points by agreement between the operator and the Met Service provider.

Question 20

• When is an AIREP Special required

Answer 20

• An AIREP Special should be made by ALL aircraft immediately to the nearest ATS unit when in the opinion of the pilot they encounter or observe hazardous met conditions severe enough to warrent a SIGMET.
• Conditions prompting an AIREP special are:
  
  • Mod - Sev Turb
  • Mod - Sev Icing
  • Sev Mtn wave
  • Thunderstorms
  • Volcanic Ash

Question 21

• Minimum Info required in an AIREP

Answer 21

• Aircraft identification
• Aircraft Position
• Time of Report
• Aircraft Altitude
• Nature of observed weather.

Question 22

• SIGMETs
  
  • What is it?
  • Validitiy?

Answer 22

• A SIGMET is issued whenever any hazardous met condition is expected to occur, or has actually been observed and reported
• SIGMETS are valid for 4 Hours
  • ​6 Hours for VA and Troplical cyclones.

Question 23

• Thunderstorms
  
  • Area of worst icing?
  • Area of worst Turbulence?

Answer 23

• Icing = Just above the freezing level from 0°C to -10°C
• Turbulance = Ahead and Below CB.

Question 24

Conditions for Radiation Fog

Answer 24

• Clear night
• Temp and Dew Point =
• Light wind 5-7kts

The Clear night allows terrestrial radiation to escape resulting in the cooling of the earth. Conduction and convection cools the air temp to the point of condesation. The breeze is required to mix the air to form fog otherwise dew forms or frost if the OAT is < 0°C

Question 25

• How is advection fog formed

Answer 25

• Formed by the transportation of moist air over a cool surface.
  
  • i.e. Sea Fog

Maybe widespread and persistent even in moderate winds

Question 26

• How is Steaming fog formed

Answer 26

• Cool air over a warm surface