Stratus clouds also form from cooling by by advection of warm air over a colder and produce stability.

Radiation fog is formed on clear nights with light winds. The ground cools losing heat through radiation. The air in direct contact with the earth’s surface is cooled. If the air is moist and the temperature is lowered below the dewpoint, fog will form.

The primary conditions conducive to the formation of radiation fog include:

1. Clear Skies and Light Winds: Clear skies allow for efficicent radiative cooling of the Earth’s surface, while light winds prevent the mixing of the air near the surface.
2. Cooling of the surface: The near surface air cool rapidly during the nighttime and this cooling causes the air temperature to drop to the dew point temperature, leading to the condensation of water vapor and the formation of fog.
3. Moist air

Here are some recommended avoidance distances:
5NM below the freezing level.

10NM above the freezing level.
20 NM when identified as severe or giving intense radar returns. If they mention thunderstorms in the question then use this distance.

This is how I think through this answer. From High to Low look out below. If you don't reset your altimeter to the new lower altimeter setting. Our aircraft will be flying closer to the ground due to the reduced outside pressure.

In this picture below we are flying at 18,000 ft.

In area 1 our altimeter is A30.02 and our indicated altitude matches our true altitude.

In area 2 our altimeter is still set to A30.02 even though the pressure dropped to A29.92. Our indicated altitude will still read 18,000 feet but our true altitude will be closer to the earth which is a hazard.

Precipitation-induced fog is caused by the addition of moisture to the air through evaporation of rain or drizzle. This type of fog is associated mostly with warm fronts and is sometimes known as frontal fog.

Advisory Circular (AC) No. 700-028
Effect of Temperature on the Vertical Profile

This barometric change will not be consistent as the ambient temperature varies from the International Standard Atmosphere (ISA). If the ambient temperature is colder, the air will be denser which will result in the target barometric change occurring in a smaller actual altitude change. The result will be a shallower than targeted profile. For example, a nominal 3° glide path may be closer to 2.5° at very low temperatures. The opposite occurs when the ambient temperature is higher than ISA.

The transponder always reports your pressure altitude assuming an altimeter setting of 29.92.

Mode C altitude transmissions are independent of the barometric altimeter. The transponder can get its information from one of two sources: an encoding altimeter, which transmits a pressure altitude reading to the transponder, or — more commonly — a blind encoder, an altimeter without needles or adjustment knob permanently set to 29.92 (pressure altitude). In either case, the altimeter setting does not affect the altitude the transponder sends.

ATC’s computers apply the current altimeter setting to the pressure altitude received, converting it to MSL (which should match your indicated altitude).

Reference: AIM COM 7.0

Sun  Up, Frequency Up

Sun Down, Frequency Down

AIM COM 4.6

Accuracy—NDB systems are flight checked to an accuracy of at least ±5 ̊ for an approach and ±10 ̊ for en route.

AIM COM 5.3.1 Aircraft-Based Augmentation System (ABAS)

RAIM and FDE functions in current IFR-certified avionics are considered ABAS. RAIM can provide the integrity for the en route, terminal, and NPA phases of flight. FDE improves the continuity of operation in the event of a satellite failure and can support primary-means oceanic operations.

RAIM uses extra satellites in view to compare solutions and detect problems. It usually takes four satellites to compute a navigation solution, and a minimum of 5 for RAIM to function. The availability of RAIM is a function of the number of visible satellites and their geometry. It is complicated by the movement of satellites relative to a coverage area and temporary satellite outages resulting from scheduled maintenance or failures.

If the number of satellites in view and their geometry do not support the applicable alert limit (2 NM en route, 1 NM terminal and 0.3 NM NPA), RAIM is unable to guarantee the integrity of the position solution. (Note that this does not imply a satellite malfunction.) In this case, the RAIM function in the avionics will alert the pilot, but will continue providing a navigation solution. Except in cases of emergency, pilots must discontinue using GNSS for IFR navigation when such an alert occurs.

A second type of RAIM alert occurs when the avionics detects a satellite range error (typically caused by a satellite malfunction) that may cause an accuracy degradation that exceeds the alert limit for the current phase of flight. When this occurs, the avionics alerts the pilot and denies navigation guidance by displaying red flags on the HSI or CDI. Continued flight using GNSS is then not possible until the satellite is flagged as unhealthy by the control centre, or normal satellite operation is restored.

Some avionics go beyond basic RAIM by having an FDE feature that allows the avionics to detect which satellite is faulty, and then to exclude it from the navigation solution. FDE requires a minimum of 6 satellites with good geometry to function. It has the advantage of allowing continued navigation in the presence of a satellite malfunction.

Most first generation avionics do not have FDE and were designed when GPS had a feature called SA that deliberately degraded accuracy. SA has since been discontinued, and new generation SBAS-capable receivers (TSO-C145a/C146a) account for SA being terminated. These receivers experience a higher RAIM availability, even in the absence of SBAS messages, and also have FDE capability.

AIM COM 5.3.1 Aircraft-Based Augmentation System (ABAS)

RAIM and FDE functions in current IFR-certified avionics are considered ABAS. RAIM can provide the integrity for the en route, terminal, and NPA phases of flight. FDE improves the continuity of operation in the event of a satellite failure and can support primary-means oceanic operations.

RAIM uses extra satellites in view to compare solutions and detect problems. It usually takes four satellites to compute a navigation solution, and a minimum of 5 for RAIM to function. The availability of RAIM is a function of the number of visible satellites and their geometry. It is complicated by the movement of satellites relative to a coverage area and temporary satellite outages resulting from scheduled maintenance or failures.

If the number of satellites in view and their geometry do not support the applicable alert limit (2 NM en route, 1 NM terminal and 0.3 NM NPA), RAIM is unable to guarantee the integrity of the position solution. (Note that this does not imply a satellite malfunction.) In this case, the RAIM function in the avionics will alert the pilot, but will continue providing a navigation solution. Except in cases of emergency, pilots must discontinue using GNSS for IFR navigation when such an alert occurs.

A second type of RAIM alert occurs when the avionics detects a satellite range error (typically caused by a satellite malfunction) that may cause an accuracy degradation that exceeds the alert limit for the current phase of flight. When this occurs, the avionics alerts the pilot and denies navigation guidance by displaying red flags on the HSI or CDI. Continued flight using GNSS is then not possible until the satellite is flagged as unhealthy by the control centre, or normal satellite operation is restored.

Some avionics go beyond basic RAIM by having an FDE feature that allows the avionics to detect which satellite is faulty, and then to exclude it from the navigation solution. FDE requires a minimum of 6 satellites with good geometry to function. It has the advantage of allowing continued navigation in the presence of a satellite malfunction.

Most first generation avionics do not have FDE and were designed when GPS had a feature called SA that deliberately degraded accuracy. SA has since been discontinued, and new generation SBAS-capable receivers (TSO-C145a/C146a) account for SA being terminated. These receivers experience a higher RAIM availability, even in the absence of SBAS messages, and also have FDE capability.

AIM RAC 6.3.3 Reporting Malfunctions of Navigation and Communications Equipment

The pilot-in-command of an aircraft in IFR flight within controlled airspace should report immediately to the appropriate ATC unit any malfunction of navigation or air-ground communications equipment.

VOR Reception Range = 1.23  x √(square root) Height of the aircraft AGL
= 1.23 x 91.65

= 112 NM

AIM COM 4.5.1 and 4.5.2

6712 feet ASL or 6800 feet ASL using Rule of Thumb

Here are some recommended avoidance distances:
5NM below the freezing level.

10NM above the freezing level.
20 NM when identified as severe or giving intense radar returns. If they mention thunderstorms in the question then use this distance.

Step 1: Find the difference between the altimeter settings
30.10 -29.92 = 0.18 in
0.18 in x 1000 ft = 180 feet. This is the altitude error.

Step 2: Add or Subtract from the aircrafts altitude
Remember these two phrases for the next part. "High to low, lookout below" "Low to high, too much sky"

In this example we are going from low to high. So we add.
5000 ft + 180 ft = 5,180 ft ASL.

VOT Signal:

With a VOT, you can check the VOR accuracy from your plane before takeoff. So what is a VOT? It's an approved VOR test signal, and it's located on an airport. Not all airports have VOTs, so you'll need to check the chart supplement to see if your airport has one. If your airport does have a VOT, here's what to do:

1. Tune your VOR to the VOT signal.
2. Set the course selector to 0 degrees, and the track indicator should be centered.
3. The TO-FROM indicator should read FROM.
4. Next, set the course selector to 180 degrees
5. The TO-FROM indicator should read TO, and the track bar should then be centered.
6. The maximum indicated bearing error is plus or minus 4 degrees.

The question is asked for the forecasted weather. A METAR is only the reported actual weather so we can ignore it. We must look at the TAF only as it is the forecasted weather.

The following TAF is for the Ottawa airport.

"TAF CYOW 141640Z 1417/1517 29006KT P6SM OVC025 TEMPO 1417/1418

OVC020

BECMG 1417/1419 28010KT

FM142200 27005KT P6SM BKN025 TEMPO 1423/1503 OVC020

FM150300 18005KT P6SM FEW020 TEMPO 1505/1508 2SM BR

FM150800 18005KT 1SM BR BKN003 PROB30 1510/1512 1/2SM -FZDZ FZFG

RMK NXT FCST BY 141800Z"

The above 24 hour TAF begins at 17:00Z.  The visibility is plus 6 SM.
The winds were initially forecast to be at 290 T at 6 knots. However, it was forecast to change by the BECMG to 280 T at 10 knots.

I admit this is a tricky question. First you have to determine all the possible alternate minimums you can have. In Canada, we can use the alternate minima + the sliding scale.

Step 1: The alternate minima given is 600-2. The associated sliding scale is 700 - 1 1/2 and 800 - 1. This is only a Canadian thing. Other parts of the world don't use sliding scales, just alternate minima only. So, we have 3 answers to choose. (600-2; 700- 1 1/2; 800-1).

Step 2: Now add all the flight times: CYYC-CYQR-CYXE = 3 hours.

Step 3: Review the TAF:

TAF CYXE 281139Z 2812/2912 24010G25KT 27050KT 5SM –SN BKN004 OVC010 TEMPO 2818/2901 1 1/2SM –SN BLSN BKN010 PROB30 2820/2822 1/2SM SN VV005 FM290200Z 28010KT 1SM –SN BKN007 BECMG 2906/2908 000000KT 1SM BKN008 RMK NXT FCST BY 281800Z

The only legal portion of the TAF is 800-1 from our sliding scale above.

Step 4: Review the CAP Gen

The weather is forecast to begin at 06Z and end of 08Z. Since the ceiling are improving we must use the END OF THE FORECASTED PERIOD.

0800Z - 3 hours flight time = 0500Z

METAR CYWG 141500Z 22012KT 15SM SCT170 OVC240 04/00 A2972 RMK AC4CI4 SLP075=

TAF CYWG 141140Z 1412/1508 20010KT P6SM SCT220
BECMG 1412/1414 27015G25KT
FM141500 27015G25KT P6SM FEW220
FM150100 25012KT P6SM SKC
RMK NXT FCST BY 141800Z

The forecasted winds at 15Z are 270 T 15 gusting to 25 knots. The actual METAR is only at 220 T at 12 knots.

Therefore the winds are better than forecasted.

TAF CYWG 141140Z 1412/1508 20010KT P6SM SCT220
BECMG 1412/1414 27015G25KT
FM141500 27015G25KT P6SM FEW220
FM150100 25012KT P6SM SKC
RMK NXT FCST BY 141800Z

Between 12:00Z on the 14th to 08:00Z on the 15th is 20 hours.

TAF CYXE 281139Z 2812/2912 24010G25KT WS011/ 27050KT 3SM –SN BKN010 OVC040 TEMPO 2818/2901 1 1/2SM –SN BLSN BKN008 PROB30 2820/2822 1/2SM SN VV005 FM290130Z 28010KT 5SM –SN BKN020 BECMG 2906/2908 000000KT P6SM SKC RMK NXT FCST BY 281800Z

In a TAF calm winds is encoded as “00000KT”.

Note: In this example: WS011/ 27050KT.  The wind shear is forecast to exist in the layer from the surface to 1,100 ft AGL, with the wind at the shear height of 270° true at 50 kt.

The question asked for the worst forecasted visibility. We have to ignore the METAR and only look at the TAF for forecasts.

TAF CYYT 141140Z 1412/1512 30007KT P6SM OVC020 TEMPO 1412/1421 5SM -SN OVC025
FM142300 34008KT 5SM OVC015 TEMPO 1423/1509 2SM -SHSN
BECMG 1502/1504 02008KT
FM150900 04010KT 3SM -SN OVC020
RMK NXT FCST BY 141800Z

The worst forecasted visibility for this period is between 23Z on the 14th to 09Z on the 5th and 2 SM.

The question is asking for lowest reported ceiling. This means the actual weather outside as written on a METAR, not a forecast.

METAR CYOW 141900Z 28006KT 10 SM BKN009 02/01 A3030

METAR CYOW 141800Z 30006KT 10SM BKN006 FEW029 BKN100 01/01 A3028

SPECI CYOW 141740Z 27005KT 10SM FEW010 BKN007 BKN100 01/01 A3027

METAR CYOW 141700Z 29004KT 15SM OVC080 01/01 A3024

The lowest ceiling is Broken 600 ft. A broken sky condition is between 5-7 oktas.

Here is a review of sky conditions (with my own memory aid):
FEW: 1-2 (One to two, is too few)
SCT: 3-4 (Three to four, scattered all over the floor)
BKN: 5-7 (Five to seven, broken up to heaven)
OVC: 8/8

The IFR outlook is in the comment section from 06-18Z = 12 hours.

The GFA comes with 3 clouds and weather charts. The first in the series is valid for 6 hours. The last in the series is valid for 12 hours.

LCL on a GFA is a surface-based layer. The vertical visibility of surface-based layers is measured in hundreds of feet AGL. This is the only time a ceiling is in AGL on a GFA. Otherwise the entire GFA is in ASL.

You have to use the legend ruler to determine the distance. On your TC exam I would use a scrap piece on paper to draw out the ruler.

The distance form the cold front to CYYU is 240 NM. The speed of the cold front is 30 NM It would take 8 hours.

Add 8 hours to the chart valid time of 0600Z = 1400Z

It helps to use a rule to visualize a draught line between the two airports. Light freezing drizzle is mentioned in the GFA text as well as the red synoptic feature.

Finally, look for the scalloped cloud lines to determine which visibility and weather to read.

A Trough is an elongated area of relatively low atmospheric pressure. Shown as a purple dash line on a GFA.

A Ridge is an elongated area of high atmospheric pressure.

A TROWAL is a Trough of Warm Air Aloft. Shown as hook marks in red and blue on a GFA.

In this example the low level jet and low level windshear are both indicated on the left side of the GFA.

This is a little tricky. The trough (dashed purple lines) are moving NE at 15 knots. You have to use the scale distance to determine where it will move in 3 hours from this GFA valid time.

The trough will carry the turbulent are with it.

Also, the freezing level is the dashed black line. It says SFC for surface. Note: In other GFA examples you can see the height of the freezing level is indicated to the nearest multiple of 2 500 ft using the standard heights in hundreds of feet above sea level (SFC, 25, 50, 75, 100, meaning surface, 2 500, 5 000, 7 500, 10 000).

Continuous precipitation is shown in a green hashed border. Showery precipitation is shown in a green solid border on a GFA.

The example GFA is asking you to refer to the comments section note B.

The 700-400mb PROG chart is equivalent to 10,000 ft - 23,000 ft. There is another prog chart for between 24,000 to 63,000 ft.

I would print the image and draw a line using a ruler to answer this question. All red areas mark turbulence and the altitudes you can expect to find them. It one of those questions where you have to take the time to look at the chart carefully.

The 700-400mb PROG chart is equivalent to 10,000 ft - 23,000 ft. There is another prog chart for between 24,000 to 63,000 ft.

Learn the symbols for moderate vs severe icing.

Anytime XX is written with the clouds groups it means that the base is below this chart level. This chart begins at 10,000 ft so the base is unknown below 10,000 ft.

Be cautious when the question asks about the issue date vs valid date. The issue date can be found in the thin blue box on the top left hand corner. The valid date is in the blue box on the right hand corner. It will always be issued well before it is valid.

The upper charts are actually issued four times daily; valid 00Z, 06Z, 12Z, 18Z.

The upper charts are actually issued four times daily; valid 00Z, 06Z, 12Z, 18Z.

The minimum fuel on board MFOB indicates 2900 kgs. The flight arrived at the waypoint with only 2700 kgs. This means we are 200kgs short of fuel.

PFOB is the planned fuel on board. There are 2 places where you can find this information on the flight plan.

MFOB is the minimum fuel at the destination.