Section 1-03 Weather Flashcards
Define Cavok
Derived from the words ceiling and visibility OK.
No cloud below 5000’ or below the highest MSA, whichever is higher, and no CB cloud
Visibility of 6 sm or more
No precipitation, thunderstorms, shallow fog or drifting snow.
How do we express wind speed and direction?
Speed in knots and direction in magnetic degrees if off a station wind gauge and tru degrees if off a METAR
When do ALtimeter settings need to be repeated twice in communication with pilots?
If they are above 31.00 or below 28.99. For above 31.00 you also need to confirm with the pilot whether they have set their altimeter correctly.
How would an altimeter read error if it was set incorrectly?
If the altimeter is higher than actual pressure the aircraft will be lower than intended. If the altimeter is set lower than actual pressure the aircraft will be higher than intended.
How is wind information presented?
Where possible use a mean wind. If it comes from a digital wind gauge we say exactly how it is listed.
Define PIREP
PIlot report of weather conditions encoutered by an aircraft in flight
Define a calm wind
Less than 2 knots on an analog gauge and 00 knots on a digital gauge
What is the error tolerance for altimeters?
PLus/minus 0.2 inches. If the discrepancy between the direct altimeter and the station altimeter is more than this we have to report it as unserviceable.
When would an altimeter reading be defined as stale? and with what amount of change would you isse a pilot a new altimeter setting?
Over an hour from report would be stale. If altimeter changes by plus/minus 0.2, issue a pilot a new altimeter.
define PDTA
Position, direction, type altitude
Name the 3 common weather observers
FSS
CWO: contract weather observers
Automated weather observations (AWOS)
Why would we issue a SPECI
an important weather event happened off the hour
Are cloud layers reported in feet AGL or ASL?
AGL
Define vertical visibility
The distance we can see vertically into a ground based layer. (We use when we cant see cloud base, it is obscured by fog or heavy precip, usually snow)
Define Ceiling
Lesser of: 1) height above ground or water of the base of the lowest layer of cloud covering more than half the sky
2) the vertical visibility in a surface based layer that completely obscures the sky
Can a controller define a ceiling?
No, controllers are not permitted to define a ceiling or estimate cloud height. They can however say if the current conditions appear discrepant with the active METAR
Define Ground visibility
Visibility at an aerodrome contained in a weather observations reported by and ATC unit, an FSS or FIC, a CARS, and AWOS or a radio statoin that is ground based and operated by an air operator (UNICOM)
Prevailing visibility
Max visibility value common to sectors comprisong more than half of the horizon circle
Are controllers empowered to make prevailing visibility determinations? And in what order would prevailing visibility determinations be used?
Yes they are.
1)RVR
2) Weather observation (METAR)
3) Tower visibility
4)Pilot visibility (PIREP)
IF there is a diffference between aviaition weather reports and controller observed conditions who should you pass that information along to? (Hint same steps as passing along a PIREP)
disseminator position (if applicable)
Concerned aircraft
Appropirate FIC
Other concerned sectors and units
When would you specify sector visibility?
When it differs notable from prevailing visibility in such a way that could be relevant
Is visibility reduced by darkness?
No
Define visibility
the greatest distance at which objects of suitable dimension can be seen and identified.
Controllers are required to use markers to declare visibility.
