Q51: Which of these clouds poses the greatest danger to aviation? ^t50q51

• A) Altocumulus
• B) Cumulonimbus
• C) Cirrostratus
• D) Cirrocumulus

Correct: B)

Explanation: The CB (cumulonimbus) is the most dangerous cloud: severe turbulence, lightning, hail, wind shear, icing.

Q52: In which situation is the tendency for thunderstorms most pronounced? ^t50q52

• A) High pressure situation, significant warming of the lower air layers, low air humidity.
• B) Slack pressure gradient situation, significant warming of the upper air layers, high air humidity.
• C) Slack pressure gradient situation, significant cooling of the lower air layers, high air humidity.
• D) Slack pressure gradient situation, significant warming of the lower air layers, high air humidity.

Correct: D)

Explanation: Thunderstorms = slack pressure gradient (low pressure gradient) + strong surface heating (instability) + high humidity.

Q53: Fine suspended water droplets reduce visibility at an aerodrome to only 1.5 km up to 1000 ft AGL. What meteorological phenomenon causes this? ^t50q53

• A) Haze (HZ).
• B) Mist (BR).
• C) Widespread dust (DU).
• D) Shallow fog (MIFG).

Correct: B)

Explanation: Visibility 1–5 km with water droplets = mist (BR). Fog = visibility < 1 km.

Q54: Which of the following situations most favours radiation fog formation? ^t50q54

• A) 15 kt / Overcast / 13°C / Dew point 12°C
• B) 15 kt / Clear sky / 16°C / Dew point 15°C
• C) 2 kt / Scattered cloud / 7°C / Dew point 6°C
• D) 2 kt / Clear sky / -3°C / Dew point -20°C

Correct: C)

Explanation: Radiation fog: light wind (2 kt), small temperature/dew point spread (1°C), some cloud acceptable. Option (C) has too large a temp/dew point spread.

Q55: The temperature recorded at Samedan airport (LSZS, AD elevation 5600 ft) is +5°C. What will the approximate temperature be at 8600 ft altitude directly above the airport? (Assume ISA lapse rate) ^t50q55

• A) +5°C
• B) +11°C
• C) -1°C
• D) -6°C

Correct: C)

Explanation: ISA lapse rate = -2°C/1000 ft. Difference: 8600 - 5600 = 3000 ft. Temperature: 5°C - (3 × 2) = -1°C.

Q56: The QFE of an aerodrome (AD elevation 3500 ft) corresponds to: ^t50q56

• A) The instantaneous pressure at sea level.
• B) The instantaneous pressure at the measurement station level reduced to sea level taking into account the ISA temperature lapse rate.
• C) The instantaneous pressure at the measurement station level.
• D) The instantaneous pressure at the measurement station level reduced to sea level taking into account the actual temperature profile.

Correct: C)

Explanation: QFE = atmospheric pressure measured at aerodrome level (station). The altimeter reads 0 on the ground.

Q57: What does the following symbol mean? (Arrow with one long barb and one short barb) ^t50q57

]

• A) Wind from NE, 30 knots.
• B) Wind from SW, 30 knots.
• C) Wind from SW, 15 knots.
• D) Wind from NE, 15 knots.

Correct: D)

Explanation: The arrow points towards the wind's origin. One long barb = 10 kt, one short barb = 5 kt. Total = 15 kt from the NE.

Q58: What are the wind speed and direction in the following METAR? LSZB 131220Z 28015G25KT 9999 SCT035 BKN075 10/06 Q1018 NOSIG= ^t50q58

• A) Wind from WNW, 15 knots, gusting to 25 knots.
• B) Wind from ESE, 15 knots, gusting to 25 knots.
• C) Wind from WNW, 25 knots, direction varying between WNW and SSE.
• D) Wind from WNW, 15 knots, direction varying between WNW and WSW.

Correct: A)

Explanation: 280° = WNW, 15 kt mean, G25 = gusts to 25 kt.

Q59: In Switzerland, cloud base in a METAR is given in... ^t50q59

• A) ...metres above sea level.
• B) ...metres above aerodrome level.
• C) ...feet above aerodrome level.
• D) ...feet above sea level.

Correct: C)

Explanation: In a METAR, cloud base is given in feet AGL (above aerodrome level).

Q60: You are flying at very high altitude (northern hemisphere) and consistently have a crosswind from the left. You conclude that: ^t50q60

• A) A high-pressure area is to the right of your track, a low-pressure area to the left.
• B) There is a low-pressure area ahead of you and a high-pressure area behind you.
• C) There is a high-pressure area ahead of you and a low-pressure area behind you.
• D) A high-pressure area is to the left of your track, a low-pressure area to the right.

Correct: A)

Explanation: Buys-Ballot's law: standing with your back to the wind in the northern hemisphere, the low-pressure area is to your left. Wind from the left = low pressure to the left, high pressure to the right.

Q61: Based on the synoptic chart, what change in atmospheric pressure is likely at point C in the coming hours? ^t50q61

Source : BAZL/OFAC Série 1 - Branches Communes Synoptic chart: ] T = depression centre. A = warm sector (between warm front and cold front). B = behind the cold front (cold air mass). C = ahead of the warm front (cool air mass). Cold front: blue triangles. Warm front: red semicircles.

• A) No notable change.
• B) Pressure will fall.
• C) Pressure will rise.
• D) Pressure will undergo rapid, irregular variations.

Correct: B)

Explanation: Point C lies ahead of the warm front, meaning the depression centre and its associated frontal system are approaching. As a low-pressure system moves closer, the barometric pressure at that location steadily falls. Option A is wrong because an approaching depression always causes pressure changes. Option C (pressure rise) would apply to a location behind a cold front where cold dense air moves in. Option D (rapid irregular variations) is more typical of the immediate vicinity of thunderstorm activity, not the broad-scale approach of a warm front.

Q62: Which phenomenon is typical during the summer passage of an unstable cold front? ^t50q62

Source : BAZL/OFAC Série 1 - Branches Communes

• A) Stratiform cloud cover.
• B) Convective cloud development.
• C) Rapid temperature rise behind the front.
• D) Rapid pressure drop behind the front.

Correct: B)

Explanation: An unstable cold front in summer forces warm, moist, unstable air upward vigorously, triggering strong convection and the development of cumuliform clouds including towering cumulus and cumulonimbus with showers and thunderstorms. Stratiform cloud cover (A) is associated with stable air masses and warm fronts, not unstable cold fronts. Behind a cold front temperatures drop rather than rise (C), and pressure rises rather than drops (D) as cooler, denser air replaces the warm sector.

Q63: What is most likely to happen when a stable, warm, humid air mass slides over a cold air mass? ^t50q63

Source : BAZL/OFAC Série 1 - Branches Communes

• A) A few scattered cumuliform clouds, rare precipitation, light turbulence, and excellent visibility.
• B) Extensive stratiform clouds with a gradually lowering cloud base and continuous rainfall.
• C) Convective clouds, heavy showers, thunderstorm tendency, and severe turbulence.
• D) Rapid drying aloft with cloud dissipation and good visibility, but dense fog in the lowlands.

Correct: B)

Explanation: When stable warm humid air overrides a cold air mass (the classic warm front mechanism), the warm air ascends gently along the frontal surface, cooling progressively and forming widespread stratiform clouds — from high cirrus down through altostratus to nimbostratus — with continuous, steady precipitation and a lowering cloud base. Option A describes fair-weather conditions unrelated to frontal activity. Option C describes unstable convective weather typical of cold fronts, not warm fronts. Option D combines fog with drying aloft, which is internally contradictory and not a recognised frontal pattern.

Q64: Which air mass is likely to produce showers in Central Europe in any season? ^t50q64

Source : BAZL/OFAC Série 1 - Branches Communes

• A) Continental tropical air.
• B) Maritime tropical air.
• C) Continental polar air.
• D) Maritime polar air.

Correct: D)

Explanation: Maritime polar air (mP) originates over cold northern oceans, picking up moisture and becoming unstable as it moves over relatively warmer European land surfaces, producing convective showers year-round. Continental tropical air (A) is warm and dry, producing clear skies rather than showers. Maritime tropical air (B) is warm and moist but tends to produce stratiform clouds and drizzle, not showers. Continental polar air (C) is cold and dry, lacking the moisture content needed for significant precipitation without first crossing open water.

Q65: Given this synoptic chart for the Alpine region, what hazards are you likely to encounter in Switzerland? ^t50q65

Source : BAZL/OFAC Série 1 - Branches Communes Synoptic chart Switzerland/Alps: ] Anticyclone (H) to the west, depression (T) to the north-east, isobars indicating NW flow over Switzerland.

• A) In winter, persistent snowfall in Ticino.
• B) In summer, widespread thunderstorms south of the Alps with severe turbulence.
• C) Continuous precipitation north of the Alps; very disturbed weather south of the Alps.
• D) Cloud-covered Alps to the south; strong gusty winds north of the Alps.

Correct: C)

Explanation: A northwest flow situation (Nordwestlage) drives moist air against the northern slopes of the Alps, producing continuous orographic precipitation on the north side. The flow also disturbs conditions south of the Alps through spillover effects and forced subsidence turbulence. Option A describes a south-side precipitation event (Stau from the south), not a northwest situation. Option B misplaces the thunderstorms on the wrong side of the Alps. Option D reverses the pattern — clouds would cover the north side, not the south.

Q66: Referring to the Low Level SWC chart, which statement is correct? ^t50q66

Source : BAZL/OFAC Série 1 - Branches Communes Low Level Significant Weather Chart (OGDD70) ] Fixed Time Prognostic Chart — Valid: 09 UTC, 22 JAN 2015 Issued by MeteoSwiss

| Zone | Cloud cover | Cloud base | Cloud top | Visibility | Turbulence | Icing | |------|-----------|-------------|---------------|------------|------------|---------| | A | BKN/OVC SC, AC | 3000 ft | FL080 | > 10 km | MOD below FL080 | MOD FL040-FL080 | | B | BKN/OVC ST, SC | 1500 ft | FL060 | 5-8 km, locally 3 km (BR) | MOD below FL060 | MOD FL030-FL060 | | C | SCT/BKN CU, SC | 4000 ft | FL100 | > 10 km | ISOL MOD | LGT FL050-FL100 |

0°C isotherm: FL040 (north) to FL060 (south). Surface wind: SW 15-25 kt.

• A) Isolated thunderstorms may occur in area C with no icing or turbulence.
• B) In area B, cumuliform clouds are expected with possible light freezing rain or freezing fog.
• C) Rain and snow showers are to be expected in area A.
• D) Area A lies between two warm fronts.

Correct: C)

Explanation: Area A features BKN/OVC stratocumulus and altocumulus with moderate icing between FL040 and FL080 and the 0°C isotherm at FL040, indicating mixed precipitation — rain and snow showers — within this zone. Option A incorrectly states no icing or turbulence in area C, whereas the chart shows isolated moderate turbulence and light icing there. Option B mischaracterises area B, which has stratiform clouds (ST, SC), not cumuliform. Option D makes an unsupported claim about warm fronts that cannot be verified from the chart data provided.

Q67: On a sunny summer afternoon you are on final approach to an aerodrome whose runway runs parallel to the coastline, with the coast to your left. On this flat terrain, what direction will the thermal (sea breeze) wind come from? ^t50q67

Source : BAZL/OFAC Série 1 - Branches Communes

• A) Crosswind from the left.
• B) Headwind.
• C) Tailwind.
• D) Crosswind from the right.

Correct: A)

Explanation: During a sunny summer afternoon, the land heats faster than the sea, causing air to rise over land and drawing cooler air inland from the sea — this is the sea breeze. Since the coastline is to your left and the runway runs parallel to it, the sea breeze blows from the sea (left side) toward the land, creating a crosswind from the left. Options B and C (headwind/tailwind) would require the wind to blow along the runway, not from the coast. Option D would require the sea to be on the right side.

Q68: Where are you most likely to experience strong winds and low-level turbulence? ^t50q68

Source : BAZL/OFAC Série 1 - Branches Communes

• A) At the centre of an anticyclone.
• B) In a transition zone between two air masses.
• C) At the centre of a depression.
• D) In a region of slack pressure gradient during winter.

Correct: B)

Explanation: Transition zones between air masses — i.e., frontal zones — feature steep horizontal temperature and pressure gradients that drive strong winds and generate mechanical and convective turbulence at low levels. The centre of an anticyclone (A) is characterised by calm, subsiding air with light winds. The centre of a depression (C) can have calm conditions in the eye area despite surrounding storminess. Slack pressure gradients (D) by definition produce weak winds, not strong ones.

Q69: An air mass at 10°C has a relative humidity of 45%. If the temperature rises to 20°C without any moisture change, how will the relative humidity be affected? ^t50q69

Source : BAZL/OFAC Série 1 - Branches Communes

• A) It will increase by 50%.
• B) It will remain constant.
• C) It will decrease.
• D) It will increase by 45%.

Correct: C)

Explanation: Relative humidity is the ratio of the actual water vapour content to the maximum the air can hold at that temperature. When temperature rises from 10°C to 20°C, the air's saturation capacity roughly doubles, but since no moisture is added, the actual vapour content stays the same — so relative humidity decreases significantly. Options A and D wrongly claim humidity increases, which would require either adding moisture or cooling the air. Option B is incorrect because relative humidity is temperature-dependent and cannot stay constant when temperature changes without a corresponding moisture change.

Q70: On 1 June (summer time), you receive the Swiss GAFOR valid from 06:00 to 12:00 UTC. Your planned route shows "XMD". What does this mean? ^t50q70

Source : BAZL/OFAC Série 1 - Branches Communes

• A) At 11:00 LT conditions on this route will be difficult.
• B) At 09:00 LT conditions on this route will be critical.
• C) At 09:00 LT the route will be closed.
• D) At 11:00 LT the route will be closed.

Correct: C)

Explanation: The Swiss GAFOR divides the validity period (06:00–12:00 UTC) into three two-hour blocks. Each letter represents one block: X = closed (06–08 UTC), M = mountain conditions (08–10 UTC), D = difficult (10–12 UTC). On 1 June, summer time (CEST = UTC+2) applies, so 06–08 UTC = 08–10 LT. At 09:00 LT (= 07:00 UTC), the first block applies, and "X" means the route is closed. Option A and D incorrectly interpret the timing or the code. Option B confuses the category — "M" is not "critical."

Q71: What does the wind barb symbol below represent? ^t50q71

] - A) Wind from NE, 25 kt - B) Wind from SW, 110 kt - C) Wind from SW, 25 kt - D) Wind from SW, 110 kt

Correct: C)

Explanation: Wind barb symbols point in the direction the wind blows from, with barbs on the upwind end indicating speed: a long barb equals 10 kt, a short barb equals 5 kt, and a pennant (triangle) equals 50 kt. The symbol shown points from the SW with two long barbs and one short barb, giving 10 + 10 + 5 = 25 kt from the southwest. Options B and D overstate the wind speed dramatically. Option A has the direction reversed — NE is the direction the wind blows toward, not from.

Q72: At what time of day or night is radiation fog most likely to form? ^t50q72

• A) In the afternoon
• B) Shortly before midnight
• C) Shortly after sunset
• D) At sunrise

Correct: B)

Explanation: Radiation fog forms when the ground loses heat by longwave radiation to space on clear, calm nights, cooling the overlying air to the dew point. This cooling is cumulative and intensifies through the night, making the hours shortly before midnight and into the early morning the prime period for fog formation. Option A (afternoon) is when solar heating is strongest, preventing fog. Option C (after sunset) is usually too early for sufficient cooling. Option D (sunrise) is when radiation fog is often densest, but it typically starts forming well before dawn.

Q73: Which typical Swiss weather pattern does the sketch below depict? ^t50q73

] - A) North Foehn situation - B) Westerly wind situation - C) South Foehn situation - D) Bise situation

Correct: D)

Explanation: The sketch depicts the Bise — a cold, dry northeast wind in Switzerland driven by a high-pressure system over northern or northeastern Europe and lower pressure to the south. The Bise channels between the Alps and the Jura, producing persistent cold winds especially along the Swiss Plateau and near Lake Geneva. Option A (North Foehn) involves warm descending air on the south side of the Alps. Option B (Westerly wind) is associated with Atlantic depressions. Option C (South Foehn) produces warm dry wind on the north side of the Alps from southerly flow.

Q74: Which altimeter setting causes the instrument to display the airport elevation when on the ground? ^t50q74

• A) QFE
• B) QNE
• C) QNH
• D) QFF

Correct: C)

Explanation: QNH is the altimeter setting that causes the altimeter to display altitude above mean sea level (AMSL). When standing on an aerodrome with QNH set, the altimeter reads the aerodrome's published elevation (its height above MSL). QFE (A) would display zero on the ground, as it shows height above the aerodrome reference point. QNE (B) is the standard pressure setting (1013.25 hPa) used for flight levels. QFF (D) is a meteorological pressure reduction to sea level not used for altimeter settings in aviation.

Q75: Which statement correctly describes the clouds in this METAR? LSGC 040620Z 23005KT 9000 -RA BKN012 09/08 Q1018= ^t50q75

• A) 5-7 oktas, base at 12000 ft
• B) 8 oktas, base at 1200 ft
• C) 5-7 oktas, base at 120 ft
• D) 5-7 oktas, base at 1200 ft

Correct: D)

Explanation: In METAR format, the cloud group "BKN012" decodes as BKN (broken = 5–7 oktas of sky coverage) with a base at 012 hundreds of feet, meaning 1,200 ft AGL. Option A misreads the height as 12,000 ft by adding an extra zero. Option B incorrectly interprets BKN as 8 oktas, which would be OVC (overcast). Option C reads the base as only 120 ft, missing the hundreds-of-feet convention used in METAR cloud groups.