ATPL Theory

ST. ELMO'S FIRE

St. Elmo's fire (also St. Elmo's light) is a weather phenomenon in which luminous plasma is created by a coronal discharge from a sharp or pointed object in a strong electric field in the atmosphere (such as those generated by thunderstorms or created by a volcanic eruption).

St. Elmo's Fire occurs when the atmosphere becomes charged and an electrical potential strong enough to cause a discharge (plasma) is created between an object and the air around it. This can happen to an aircraft flying through heavily charged skies.
The nitrogen and oxygen in the Earth's atmosphere cause St. Elmo's fire to fluoresce with blue or violet light; this is similar to the mechanism that causes neon lights to glow.

While not a hazard in itself, St Elmo's Fire is an indication of Thunderstorm activity and may be a precursor to a Lightning strike.

Calculating Cloud Tops With Weather Radar Tilt

It is possible to determine the height of the top of a cloud by using the weather radar tilt control.

The original formula utilizes the 1:60 rule and can be simplified to: ΔCloud Top = (Tilt Angle - ½ Beam Width) x 100 x Distance

In the attached picture we are assuming that the lowest tilt that does not produce any reflection is 5°. As the beam has a certain width (in this example 4°), we are trying to figure out the angle from the aircraft to the top of the clouds; as you can see, half the beam width has to be subtracted from the tilt, which gives us an angle of 3°. Multiplied with 100 and the distance 60 we get 18000ft, which is the height of the cloud above the aircraft height. So if the aircraft was in FL200, the top of the clouds would be in FL380.

On a side note, according to the Airbus FCOM for the A320, only the tilt angle has to be taken into account, not the beam width.

Also the formula above is only an approximation, to get an "exact" result, you can use ΔCloud Top [ft] = tan(Tilt Angle - ½ Beam Width) x distance [NM] x 6076. In this example, our result would be 19100ft. The simplified version using the 1:60 method gets more accurate with small angles and/or short distances.

MACTOW.. we see it on our loadsheets every day. But do you remember what it is?

MAC stands for Mean Aerodynamic Chord, TOW stands, obviously, for TakeOff Weight.

The width of the wing (from the leading edge to the trailing edge) , measured parallel to the relative airflow over the wing, is called chord, or chord line. For swept wings (and any other non-rectangular wing design) the chord length differs depending on where you measure it on the wing (for example, the chord on a swept wing will get shorter from root to tip). So for weight&balance calculations, trim setting determination and CG%, the local chord line is NOT what we need. What we do need is an average Chord, or MEAN Chord, so we can express the location of the centre of gravity by means of a % of the mean (aerodynamic) chord.

To clearify: when the MAC of a wing is 5 meters, and the MACTOW on the loadsheet indicated 20%, this means that the location of the centre of gravity for the takeoff weight is at 20% of 5 meters from the beginning of the MAC on the wing. So 1 meter behind the most fwd point of the MAC.

illustration source: skybrary.aero

EFFECT OF WEIGHT ON V1 speed.

With limiting runway length, the V1 speed will be lower for a higher weight to cater for the longer stopping distance required. But remember, the minimum value of V1 can never be less VMCG (Minimum Control speed on Ground).

Now imagine a very very long fieldlength that is not limiting. In this case the V1 speed will increase with increased weight, providing the V1 value remains below Vmbe (maximum brake energy speed).

Now a question for you: can you explain what is VMCG? And what is the difference between VMCG and VMCA?

Good evening everybody. I have received many messages asking whether or not this page is still active. I must admit I was very busy lately and did not post for a long time. However, as from today I will try to start posting regularly again. If you have any suggestions on subjects or particular questions that you want to get an answer to, please let me know in the comment section below. Keep in touch!

Here's an excellent Cathay Pacific CRM video, definitely worth watching

Mission Implausible - A Flight to Calamity (CRM Training Video) This training video is a little dated (and rather poor quality), but it's still a useful tool. We've made minor edits to the original video (with permission)...

Alert Height (AH)

An Alert Height is a height above the runway, based on the characteristics of the aeroplane and its fail-operational automatic landing system, above which a Category III approach would be discontinued and a missed approach initiated if a failure occurred in one of the redundant parts of the automatic landing system, or in the relevant ground equipment.

The AH is evaluated during aircraft certification; it is set at 100ft for A320FAM and 200ft for A330, A340. The AH is only linked to the probability of failure(s) of the automatic landing system. Operators are free to select an AH lower than the AH indicated in the AFM but not a higher value. Airbus procedures include both AH and DH concepts for all Fail-operational Category III operations.

If a failure occurred in one of the required redundant operational systems (fail operational systems) during a CAT II or III approach below this height, the approach would be discontinued and a go-around executed.

VHF Omni Directional Radio Range (VOR)

A VOR is a type of short-range radio navigation system for aircraft, enabling aircraft with a receiving unit to determine their position and stay on course by receiving radio signals transmitted by a network of fixed ground radio beacons. It uses frequencies in the very high frequency (VHF) band from 108.10 to 117.95 MHz.

A VOR ground station sends out an omnidirectional master signal, and a highly directional second signal is propagated by a phased antenna array and rotates clockwise in space 30 times a second. This signal is timed so that its phase (compared to the master) varies as the secondary signal rotates, and this phase difference is the same as the angular direction of the 'spinning' signal, (so that when the signal is being sent 90 degrees clockwise from north, the signal is 90 degrees out of phase with the master). By comparing the phase of the secondary signal with the master, the angle (bearing) to the aircraft from the station can be determined. This line of position is called the "radial" from the VOR. The intersection of radials from two different VOR stations can be used to fix the position of the aircraft, as in earlier radio direction finding (RDF) systems.

The signals are line of sight between transmitter and receiver and are useful for up to 200 miles. Each station broadcasts a VHF radio composite signal including the navigation signal, station's identifier and voice, if so equipped. The navigation signal allows the airborne receiving equipment to determine a bearing from the station to the aircraft (direction from the VOR station in relation to Magnetic North). The station's identifier is typically a three-letter string in Morse code. The voice signal, if used, is usually the station name, in-flight recorded advisories, or live flight service broadcasts. At some locations, this voice signal is a continuous recorded broadcast of Hazardous Inflight Weather Advisory Service or HIWAS.

By 2000 there were about 3,000 VOR stations around the world including 1,033 in the US, reduced to 967 by 2013 with more stations being decommissioned with the widespread adoption of GPS.

A very interesting article about the QZ8501 flight and what might have caused it

https://fearoflanding.com/accidents/accident-reports/the-high-altitude-stall-of-airasia-qz8501/

The High Altitude Stall of AirAsia QZ8501 On the 28th of December 2014, Indonesia Air Asia flight QZ8501 disappeared mid-flight on a routine journey from Surabaya, Indonesia to Singapore. On the 1st of December 2015, the Komite Nasional Ke…

Point of Safe Return (PSR) / Point of Equal Time (PET)

Also known as “Critical Point” and “Point of No Return”, these two formulas should be considered when planning a flight and can help making decisions in an emergency.

PSR is the point furthest from the airfield of departure that an aircraft can fly and still return to base within its safe endurance. (Safe endurance is the time an aircraft can fly without using the reserves of fuel that are required)

PSR Example:
SE is 6h, TAS 220kt, 45kt tailwind
PSR = (6x175) / (265+175) ≈ 2,39h ≈ 143min
2,39h ≙ 633 NM

PET is the point where time to destination is equal to the time to return to aerodrome of departure.

PET Example:
A and B are 600 NM apart, TAS 300kt, 50kt headwind
PET = (600x350) / (250+350) = 350 NM

Very interesting and must-watch clip! Always remain VIGILANT!

[REAL ATC] Delta and Southwest VERY CLOSE CALL on takeoff ---MORE REAL ATC VIDEOS--- https://www.youtube.com/playlist?list=PLi0SM524ylKVKmMKHSxwjfefM5PC2sjq-

A fellow colleague and B737 airline captain started this very educational and professional Youtube channel. Make sure to check it out!

Mentour Pilot Hi! On my channel I will give you my point of view from inside the airline industry! Everything from descriptions of procedures to hints about how to access ...

Check out this very informative video about how to be a good First Officer and how to prepare for Command.

How to be a good First Officer How do you deal with troublesome captains? When do you need to start preparing for command upgrade and how do you do that? What can you expect from your MCC ...

Recycling of cabin air

Cabin air is drawn by electric fans through HEPA filters, which remove bacteria and other organic matters. The air is then passed into a mixing unit, where it is mixed with air from the packs. This re-oxygenates the recycled cabin air, while the recycled air helps to humidify the fresh air.
Air from toilets and galleys is drawn by a separate duct and vented directly to the atmosphere.
Reusing cabin air reduces the operating costs, as the reduction of air taken from the engines increases the engines’ efficiency.

On an A320 for example the system is designed to replace the total cabin air up to 30 times per hour with approximately 50% fresh air and 50% recycled air.

Intermediate Approach Segment.

The intermediate approach segment is designed to give the aeroplane a chance to prepare for the final approach (speed & configuration). During the design, the descent is kept as shallow as possible and the obstacle clearance requirement in the primary area reduces from 984ft to 492ft (reduces laterally to zero at the outer edge of the secondary area).

Where a FAF is given, the intermediate approach segment starts on the inbound leg of the procedure turn or on the final inbound leg of a racetrack procedure and ends at the FAF. Where no FAF is specified, the inbound track is the final approach segment.

Approach climb limit/gradient & Landing climb limit/gradient

An aircraft can be either approach climb limited or landing climb limited. Both are considered, whereafter the most limiting one will be taken into account. Operationally these weights will allow an aircraft to execute a missed approach in most configurations. In some aircraft you will find that one of these limitations is always more restrictive, therefore you will only see one chart.
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Approach Climb

Allows for a missed approach where the go-around must be flown with the aircraft in the approach configuration. The steady gradient may not be less than:

2.1% for 2 engine aircraft
2.4% for 3 engine aircraft
2.7% for 4 engine aircraft.

The approach climb is demonstrated with:
• the critical engine inoperative and the remaining engines at takeoff thrust
• maximum landing weight
• a climb speed not exceeding 1.4 Vsr (EASA) or 1.5 Vs (FAR).
• the landing gear retracted.
• approach flaps selected
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Landing Climb
Landing climb gradient charts are calculated for go-around with the aircraft in the landing configuration. Both FAR and EASA require the steady climb gradient to be not less than 3.2% with:

• both engines operating, at the thrust available 8 seconds after the thrust levers are increased from the minimum flight idle to the takeoff thrust position
• landing gear extended
• landing flaps selected

There are two basic types of SID (Standard Instrument Departures):
1) straight departures (initial departure track is within 15° of the alignment of the runway centre line)
2) turning departures (>15° initial departure track. Straight flight is assumed until reaching an altitude/height of at least 120 m (394 ft))

SIDs are based on track guidance acquired:

a) within 20.0 km (10.8 NM) from the departure end of the runway (DER) on straight departures; and

b) within 10.0 km (5.4 NM) after completion of turns on departures requiring turns.

Track guidance may be provided by a suitably located facility (VOR or NDB) or by RNAV.

source: ICAO DOC8168 VOL 1

For a jet engine, the critical engine is usually the (outboard) engine located on the upwind side of the aeroplane.

ASDR (accelarate stop distance required) will INCREASE when the runway has an upslope.

A Single Engine Piston aircraft belongs to Performance Class B.
Vrotate voor SEP should be at least the stall speed.
The TODR ends at the screen height (50ft) where the speed should be at or above "clear 50 speed" which is 1,2VS1.

For a Tropical Storm to form (different names per regions are Thyphoons, Cyclones and Hurricanes) the following conditons have to be met (six prerequisits):
-a preexisting low level disturbance
-sufficiently warm seawater temperatures, minimum 26,5 C (79,7 F) to a depth of 50meters
-atmospheric instability
-high humidity in the lower levels of the troposphere
-sufficient Coriolis force to sustain a low pressure center (>5degrees from the equator)
-low vertical windshear

VORTEX GENERATORS

Small components placed on aerofoil surfaces (e.g. wings and stabilizer) creating a turbulent airflow and thereby delaying boundarylayer separation and thus improving the effectiveness of the aerofoil (and controlsurface if applicable). Especially during climb, at high AOA and slow speeds.

Lighting designations on air navigation obstacles.

Greater than 150m (492ft): high intensity flashing white lights (both day and night).
NOTE: any failed lights can be found in a NOTAM.

Less than 150m but higher than 300ft: medium intensity flashing red lights (at night).
NOTE: lit only when these obstacles are considered significant to air traffic.
NOTE: wIll NOT be NOTAMed when failed

Piston engines - Exhaust smoke colours:

*blue exhaust smoke indicates an oil burn in the cylinders.
(likely to occur when the piston rings are broken, causing oil to enter the combustion chamber)

*White exhaust smoke (steam smoke) indicates a high water content in the combustion chamber.

*Black exhaust smoke indicates carbon granules burning in the cylinders.(too rich mixture, result: Some of the fuel will not be burnt and will turn into carbon granules)

Actual landing (demonstrated) with no yoke action (only power, rudder and trim).
Very interesting and educational video as this technique might save your life one day. Lets hope you never need it though!

A Pilot's worst nightmare, landing without primary controls Watch an actual landing without a yoke, therefore without any ailerons or elevator. Listen to an expert CFI prepare for the approach and landing. Using the r...

For performance class A aircraft, the minimum value of Vrotate is V1, and 1,05 * Vmca.

There is a difference in climb requirements assumptions for a Missed Approach (go-around at or above DA(H)) and a Balked Landing (go-around below DA(H) and possibly during the flare);

First of all, both use go-around thrust. However, during a missed approach, n-1 is assumed, whereas during a balked landing n is assumed

During a missed approach, the required climb gradient is assumed with approach flaps and landing gear retracted.
During a balked landing, the required climb gradient is assumed with landing flaps and landing gear extended.

Interesting.. What are your thoughts on this?

A very ignorant British Airways pilot at Dublin On Christmas Eve, with 8 in sequence for runway 28 at Dublin, a British Airways pilot flying an A319 was being extremely rude to a controller at Dublin at it...

Cold-Soak Effect

The wings of an aircraft are said to be 'cold-soaked' when they contain very cold fuel as a result of having just landed after a flight at high altitude or from having been refuelled with very cold fuel.
Whenever precipitation falls on a cold-soaked aircraft on the ground, clear ice may form.

Merry Xmas !

Holdover Time (HOT) is the estimated time for which an anti-icing fluid will prevent the formation of frost or ice and the accumulation of snow on the protected surfaces of an aeroplane, under specified weather conditions.
Holdover Time is determined by the extent to which it is expected that applied fluid will remain active on the aircraft surfaces; active fluid must be able to provide protection from the accretion of frozen or semi-frozen contaminants in the prevailing conditions. Holdover Time begins at the start of the anti icing operation. If a two-step operation is used, then it begins at the start of the final (anti-icing) step. By definition therefore, holdover time will have effectively run out when frozen deposits start to form or accumulate on treated aircraft surfaces.

Due to their properties, Type I fluids form a thin liquid wetting film, which provides only an extremely limited holdover time, especially in conditions of freezing precipitation. With this type of fluid, no additional holdover time can be obtained by increasing the concentration of the fluid in the fluid/water mix.

For ‘thickened fluids’ of Type 2, 3 and 4, their pseudo-plastic thickening agent enables the fluid to form a thicker liquid wetting film on aircraft surfaces which can then provide a significantly longer holdover time, especially in conditions of continuing freezing precipitation. With this type of fluid, additional holdover time will be provided by increasing the concentration of the fluid in the fluid/water mix, with maximum holdover time available from undiluted fluid.

to read the full article see this link http://www.skybrary.aero/index.php/Holdover_Time

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