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ABC > Course 5 - Section 14 - Aviation Weather Reports > Flashcards

Course 5 - Section 14 - Aviation Weather Reports Flashcards

1
Q

What does METAR stand for?

A

Aerodrome Routine Meteorological Report

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2
Q

What does TAF stand for?

A

Terminal Area Forecast

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3
Q

METAR overview

A

Metar is the most common format in the world for transmitting obersvational weather data. METARs are prepared by staff working onsite at specific aerodromes

A METAR IS NOT A FORECAST – it gives a snapshot of weather through a sequence of codes

In Canada, METARs are generated using computer software and are based on observations taken at either staffed or automatic sites

METARs use international coding standards, but there are some national variations. Most countries, including Canada, report wind speed in knots, as per ICAO standards, but some countries, including North Korea, Russia nd China, report it in metres per second

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4
Q

METAR
Code: MESSAGE TYPE
***

A

There are two possible message types:

METAR
indicates a scheduled observation taken on the hour (plus or minus ten minutes)

SPECI
indicates an unscheduled or “special” observation reporting weather events that were not previously reported

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5
Q

METAR
Code: Day/Time

A
  • first two digits indicate the day of the month
  • last four digits indicate time in UTC/Zulu
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6
Q

METAR
Code: Wind

A

Direction

  • First three digits indicate wind direction to the nearest 10 degrees true (based on an average of two minutes)
  • If the wind direction is variable, the direction is coded VRB when speed is less than three knots (eg VRB02KT)
  • With a mean wind speed of three knots or greater, if the variation of the wind direction is 60 degrees or more and less than 180 degrees, direction is indicated with a V (eg 180V250)

Speed

-Following two digits indicate mean speed and unit (KT =knots, MPS = metres per second)
- If gusts exceed mean speed by 5 knots ore more and are at least 15 knots, use G followed by maximum speed
- if wind is calm, use 00000KT

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7
Q

METAR
Code: Visibility

A

Prevailing Visibility

-Prevailing visibility is reported in whole and fractions of statute miles (SM) up to 3 SM and in whole statute miles up to 15 SM
- If the station has visibility markers (such as mountains or large buildings), visibility greater than 15 SM can be reported in increments of 5 SM
- Visibility that is half or less, or double or more of the prevailing visibility is reported in the Remarks section (at the end of the report)

Runway Visual Range

  • If prevailing visibility is 1 SM or less AND/OR RVR is 6000 feet or less, RVR is reported
  • RVR of P6000 means it is more than 6000 feet, the highest value reported
  • RVR of M300 means it is less than 300 feet, the lowest value reported
    -Always begins with the letter R, followed by the runway heading
    -Last four digits report the visibility in feet
  • If value has changed by 300 feet or more in 10 minutes, trend is reported (D = Downward, U = Upward, N = No change)

Example
3/4SM R36/4000FT/D

Visibility is 3/4 of a SM and at R36, the RVR is 4000feet and trending downward

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8
Q

METAR
Code: PRESENT WEATHER

A
  • Reported if significant weather is observed
  • is broken down into qualifiers and weather phenomena

EXAMPLE
-SN BLSN
Light snow and blowing snow

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9
Q

METAR
Code: SKY CONDITION

A
  • Specifies amount of cloud using abbreviations:
    SKC Clear
    FEW few
    SCT scattered
    BKN Broken
    OVC overcast
  • Lists the height of the base of the clouds in FEET AGL
  • Is reported for each layer of cloud

Example BKN008 OVC040

broken cloud layer at 800 feet
overcast cloud layer at 4000 feet

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10
Q

METAR
Code: TEMPERATURE/DEW POINT

A
  • given in celcius
  • if below zero, will have M in front for minus
  • observed values with .5 degree are rounded up to the next warmer degree

Example
M05/M08

Temperature -5 deg C
Dew point -8 deg C

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11
Q

METAR
Code: Altimeter

A

reported in inches of mercury with decimal point omitted

eg. A2992
29.92 inches of mercury Hg

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12
Q

METAR
Code: RECENT WEATHER

A
  • If applicable, significant weather phenomena observed since the last routine report but not occurring at the time of observation is reported
  • Supplemental information on wind shear is provided

example WS RWY36
Wind shear at runway 36

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13
Q

METAR
Code: REMARKS

A
  • Consists of any observations of significance to aviation
  • begins with RMK

-includes, in the following order:
Type of cloud layer
Amount (in oktas)
General weather remarks
Sea level pressure

  • THE = SIGN indicates the END OF THE METAR
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14
Q

Qualifiers

A

Qualifiers always go BEFORE the weather phenomenon, no qualifier means moderate

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15
Q

Cloud Cover
(What info does sky condition give you and describe the oktas)

A

The sky condition codes give you two key pieces of information:
- The amount of cloud cover at each cloud layer
- The height of the base of each cloud layer

The type corresponds to the portion (in eights or oktas) of the sky covered by a layer of cloud. Note that cloud cover is cumulative. This means that each reported layer amount includes the sum of layers below it

(See chart)

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16
Q

Cloud height

A

Cloud height is reported in hundreds of feet

  • If CB or TCU clouds are present, they are reported after the height eg SCT023TCU is reporting scattered TCU clouds at 2300 feet
  • Obscured sky is reported as vertical visibility (VV) and is measured in hundreds of feet. eg VV001 is reporting an indefinite ceiling with vertical visibility of 100 feet

-Partially obscured sky is reported as SKC (if there is no cloud) or is included with the first layer

NOTE: From this section of the METAR, you can deduce the ceiling by determining the height of the lowest layer of clouds that are either BROKEN OR OVERCAST

17
Q

Cloud height example

A

Look at illustration

  • in the first level at 1500 feet, we see clouds covering two of eight oktas of the sky.
    FEW015

-in the next level of 3000 feet, there is only one cloud we can see directly, the other one is obscured. to get the code we add the 2 clouds we see at 1500 plus the one cloud at 3000 to get three of eight oktas. This is coded as
SCT030

  • In the last layer of cloud at 5000 feet we have an unobscured view of clouds covering to of eight oktas. adding this to the three oktas for the lower level clouds already counted, we get 5 of eight oktas which is coded as
    BKN050
18
Q

Ceiling

A

Will be the lowest cloud layer reported as BKN or OVC

(VV or SKC may override this, check!)

19
Q

Sea level pressure

A

Add a 10 in front and a decimal between last two numbers and you get SLP in hectopascals

SLP134 is 1013.4 hP

20
Q

TAFs

A

TAFs describe weather forecast information for a specific period of time

THEY ARE ISSUED AT LEAST FOUR TIMES A DAY, EVERY SIX HOURS, STARTING AT 0000Z

CANADIAN TAFs HAVE VARIOUS VALIDITY PERIODS AND CAN BE VALID FOR UP TO 30 HOURS

TAFs use the same codes and units as METARs

21
Q

TAF

Code: MESSAGE TYPE

A

TAF
This is a TAF message type

22
Q

TAF

Code: Day/Time

A
  • First two digits indicate the day of the month
  • last four digits indicate time in UTC/Zulu

This code represents the date and time the TAF was issued or amended

23
Q

TAF

Code: VALID TIME PERIOD

A

A TAF can be valid up to 30 hours

  • First two digits indicate start date and the following two digits indicate the start hour
  • after the slash, first two digits indicate the end date and the last two digits indicate end hour

eg 2714/2802
Starts on the 27th at 1400Z
Ends on the 28th at 0200Z

24
Q

TAF

Code: INITIAL FORECAST CONDITIONS

What do they describe ?

A

These are the conditions forecast at the start of the validity period of the TAF

Describes wind, visibility, weather and sky condition

eg 35005KT P6SM SKC

wind blowing from 350 at 5 knots, visibility more than 6 statute miles, sky clear

25
Q

TAF

Code: CHANGE GROUPS

A

Change groups indicate that a change in some or all of the elements is expected

26
Q

TAF

Code: REMARKS

A

Remarks, errata and comments

27
Q

BECMG Example

A

*** NOTE THAT BECOMING MEANS THE CHANGE TAKES PLACE GRADUALLY DURING THE WINDOW SPECIFIED. THE CHANGE IS FINALIZED AT THE END OF THE WINDOW, LOOK AT EXAMPLE

28
Q

TEMPO Example

A
29
Q

TAF Multiple change group example

A
30
Q

Remember about TAFs

A

They will start with INITITIAL CONDITIONS which occur at the beginning of the valid period of the TAF. Those conditions will be in place until a CHANGE GROUP in the TAF modifies them (permanantly or temporarily)

31
Q

Remember about FM:

A

It’s a rapid change that is not temporary

ABC (31 decks)

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