Hello, IFC!
As I’ve been here for quite some time now, I have realized that this forum has changed a lot. Mainly, it has gotten more professional. In the old days, people were learning about aviation, asking questions, and discovering the wonders of our flying world.
Now, there is a much more strict format that needs to be followed (for the best) however I’m almost certain that people still have questions about aviation, but just don’t dare to ask them here.
I have gone through the IFC and similar aviation forums and platforms and have written down the most usually misunderstood or alien topics and subjects. Rather than acting smart and explaining a lot of terms that new users may not know, I’ll try a new way of answering questions… Explaining them for a five-year-old level.
DISCLAIMER:
Now since aviation is complex and there’s a reason why 5-year olds aren’t allowed to be pilots, I will try my very best to explain these subjects in the most depth possible while keeping it simple and easy to understand. This is not a very much in-depth explanation of each subject, but a general understanding for aviation beginners and people who may not be very familiar with english.
Ok let’s go.
Aircraft Lights
An airplane has a LOT of lights, but let’s look at the main ones:
Navigation lights are red and green on each wing with a white on the back of each. These allow other planes to see what direction the plane is going (where it’s left and right side is). These should be turned on as soon as the airplane is turned on. The left wing has the red light and the right wing has the green. This is intended so at night, you can always tell which direction an aircraft is relative to you.
Beacon lights are red flashing lights on the top and bottom of the plane. These let everyone know that the plane is active and that the aircraft is dangerous to go near. These should be turned on when turning on the first engine (or before pushback if pushback is needed) and turned off once the last engine has been turned off.
Strobe lights are white flashing lights on each wingtip that almost blinded me in 2020. These things are BRIGHT (unlike me). These show what the airplane’s shape and size is. These are to be turned on once you passed the hold short line and should be left on until you leave the runway at your destination.
Landing lights are lights on the wings and/or landing gear that illuminate the runway for the crew to see it. These should be turned on when you are on an active runway (at the same time as the strobe lights) but should be turned off at or above 10,000 feet. They should be turned back on at descent when you reach 10,000 feet and left on until you exit the runway.
Airspaces
As some of you may know, the sky is divided into parts called Airspaces. Airspaces are sections of sky that are controlled (or not) by different people, frequencies, etc. And are used in different circumstances.
Airspaces look like a mess. This can be seen on a 2D map. However, they are neatly organized on a 3D layer chart such as below:
Credit: FlightLiteracy
Although explaining each airspace’s characteristics and defining features would take ages, here is a basic sum up of each type.
Class A:
18000 - 60000 ft MSL
IFR flying only unless specifically allowed
Class B:
Ground altitude - 10000 ft MSL
Around major airports
Has multiple layers, each airspace is individual and specific to the airport.
Class C:
Surface - 4000ft AAL (above airport level)
Operational control tower, also serviced by a radar approach controller
Located around airports
Class D:
Surface - 2500 ft AAL
Has operational tower control
Located around airports
Is individually tailored and has specific characteristics
Class E:
There are different types of class E airspaces but essentially it’s all the empty areas that are not A, B, C, or D airspace. (Basically the majority of the US is class E airspace)
Has control to keep minimum separation and maximum safety when flying, especially in IFR
Up to 18,000 ft MSL and everything above 60,000 ft MSL is Class E
Class F: There is no such thing as Class F
Class G:
Class G is everything that is not in the above categories
It is completely uncontrolled airspace.
You must maintain a safe flying distance from all aircraft
Stay safe even without control in these airspaces!
Airspeed / Ground Speed (AS/GS)
Airplanes are fast. In fact, one could say they are speedy. But what is the difference in between air speed and ground speed?
I could redirect you to Wikipedia so you can read 900 lines of boring math but I’ll sum it down to very simple points.
Airspeed is how much air you are going against. Say that you are a plane going 100kts in air with no wind. Then your airspeed would be 100kts. If you have 20kts of wind going against you, you have an airspeed of 120kts. If the wind is pushing you, you have 80kts of airspeed.
Similarly, if you are standing still on a windy day, you will have 0kts ground speed (GS) but will have a few kts of airspeed due to the wind hitting your face.
Ground speed, on the other hand, is the speed at which you are traveling compared to the ground. No matter of wind, ground speed is your speed compared to objects on the ground. If you are running at 5kts towards strong winds, your ground speed will still be 5kts. If you are flying at 100kts and have no wind, then your ground speed is… 100kts :)
1)Wind Speed: how fast the cloud is moving toward the mountain
2)TAS: how fast you are moving toward the cloud
3)GS: how fast you are moving toward the mountain
4)IAS: how much dynamic pressure (“wind bite”) for the wing (and flaps etc.)
due to the speed of the relative wind (TAS) adjusted for how “thick” is that
moving air (density due to altitude adjusted for temperature)
5)Mach: how fast you are moving toward the cloud as a fraction of the speed of sound (again TAS)
ATC
ATC means “Air Traffic Control”. It is the system of technology and people that track where aircraft are and maintain safety in the air. Basically, ATC is a savior, be nice to ATC, they work in a high-stress environment to maintain our safety. ATC talks to pilots on different frequencies to give them information or instructions on where they are, what they must do, and how to stay safe. If you want to give it a listen, go to liveatc.net and pick an airport!
Center Frequency
Center frequencies are frequencies that control a certain region, rather than an airport. These can be organized by location, altitude and other factors, making them a big mess. During cruise, you pass from one Center frequency to another and they give you directions to keep you safe from collisions, etc. Center frequencies are different from approach and departure as these two are for a specific airport, and focus on lining you up for a specific runway. Center just makes sure you’re safe during cruise and that the pilots don’t fall asleep 😉
Dew Point
Imagine the air is a glass. A glass can only hold so much water before it spills, right? The air is the same! It can only hold so much humidity before it “spills” and puts droplets of water on surfaces. The moment when the glass “spills” and causes droplets is called the Dew Point. This is important for pilots as it can cause icing on the wings at lower temperatures, for example.
Note that the amount of water that can be held in the air increases when it gets hotter. If you’ve ever woken up and seen wet grass despite it not having rained, that’s because you are at or below the dew point.
What do you see on the grass?
Dew!
(Not Mountain Dew)
ETOPS
ETOPS stands for “Extended-range Twin-engine Operational Performance Standards”. ETOPS is a rating that aircraft are given as to how far they can travel on two engines to maintain safety. An aircraft can have a 120 minute ETOPS for example, meaning it can fly as far as 120 minutes away from the nearest airport. This is needed for long haul flight above the Atlantic for example.
To put it simply, if the aircraft has a 120 minute ETOPS and is 121 minutes away from the closest airport, then it’s a problem.
Flight Levels and Heading
You might have heard ATC telling you to go to a flight level such as “flight level 270”. But what are these? Flight levels are an aircraft’s altitude that varies. To find your flight level, set your altimeter to the standard 29.92. In this case, flight level 270 would be 27,000 feet. Another example is FL450, which is 45,000 feet.
Now, there is a precaution put in place to avoid collisions. If you are flying between 1 and 180 degrees, your flight level must have an odd second digit. If you are flying between 181 and 360 degrees, the second digit must be even. Finally, to make things harder, if you are flying VFR, you must be under 17999 and must be flying at x500 feet for separation (like 1500 feet, 2500 feet etc).
Flying IFR? That would be 260, 280 and 300 when heading west and 270, 290 and 310 when heading east.
IFR / VFR
IFR means “Instrument Flight Rules”. To put it simply, an IFR rating means that pilots are allowed to fly while relying on their cockpit instruments. This allows them to fly at night, in clouds, fog, etc.
VFR means “Visual Flight Rules”. Basically, the pilot can fly in clear weather, light rain and during daytime and night. The pilot cannot fly if the weather conditions require an IFR rating.
Lift, Flaps & Everything in Between
Lift is what makes planes fly. Without lift, planes wouldn’t take off (which is not a good thing unless it’s Air France). But… how do planes do the thing?
Let’s look at a wing from the side to understand better :)
Credit: Me and MS Paint
In black is a slice of plane wing seen from the side.
In green is the relative air. This is the air coming towards the front of the wing. For more explanations, check explanation #2.
In blue is the air depression.
In yellow is the air surpressure (overpressure).
In red is the wing chord. This is the line from the leading edge to the trailing edge of the wing.
Finally, in orange is the angle of attack.
Now, for the explanation you have been waiting for.
When the air hits the front of the wing (leading edge), it either goes above or under the wing. Both these trips end up at the same place (the trailing edge) but going over the wing is a longer journey. This asymmetrical wing shape causes depressed air on top of the wing and suppressed air on the bottom. This allows the airplane to “rest” on the air under the wings. This is called lift. Lift goes against weight, allowing the plane to fly (unless you are flying Air France).
There you go, a simple explanation of how planes fly.
If you have a hard time visualizing it, stick your hand out of a car window (going fast) as a straight, flat palm and then curve it to imitate a wing. The hand will come up against your will!
Now, what is the angle of attack? It’s just the difference between the wing chord and the angle of the relative wind.
Next up, Flaps!
What even are flaps??
Flaps are… well… flaps of metal. These fold out of the plane’s wing (on the trailing edge) when the additional lift is needed at slow speeds. You will likely see these in action during takeoff, descent and landing.
Here is a picture of a flap:
Credit: me
Aircraft: DA40
What do they do, how do they work?
When you are flying slowly (during takeoff and approach), the wings won’t create enough lift. This is because the air won’t be going as fast relative to the wing so the plane can’t rest on the air. This leads to stalls and nosedives, not pretty…
How do planes solve this problem?
FLAPS! WOHOO! LET’S HEAR ONE FOR THE FLAPS!
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During takeoff, flaps exaggerate the curved shape of the wing and make it bigger, allowing the plane to rest on more air, even when flying slowly. This creates lift, which makes the airplane take off (unless you are flying Air France).
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During approach, flaps exaggerate the curved shape of the wing and make it bigger, allowing the plane to rest on more air, even when flying slowly. If it weren’t for flaps, planes would have to land faster, needing bigger runways, bouncing, etc.
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During landing, flaps create drag to help slow the plane down as fast as possible.
To sum up:
Flaps create lift and drag, allowing planes to fly slowly and be more maneuverable.
Flaps during takeoff:
Flaps on approach:
Flaps on landing:
Wait, what are those things going up in the last picture?
It’s ✨Spoiler✨Time✨
Spoilers, despite their name, are pretty cool. Spoilers and speedbrakes are different however I will explain both in the same box because they work the same way.
Speedbrakes:
These bad boys are metal flaps that erect from the wing when the aircraft is overspeeding or going too fast for the situation. By going up, these “break” the smooth shape of the wing. This slows down the air and creates drag, slowing the plane down. To activate them in IF, go to spoilers > Flight and see the plane slow down.
Spoilers:
Spoilers come out during landings, aborted takeoffs, etc. Basically, when the aircraft is on the ground and needs to slow down.
Spoilers do 2 main things:
Slow the aircraft down by increasing drag
Breaks lift to pin the aircraft to the ground.
These are most commonly used for landings. If it weren’t for spoilers, the plane would not only take forever to slow down, but it would also likely bounce. This is because it’s going fast enough to fly (kinda) so the plane just bounces off the runway and aims for the stars. Spoilers break that habit and keep it pinned to the ground.
Here are some diagrams and pictures of spoilers to explain the concept:
A stunning work of art
Picture and art by me
That’s it!
METAR
So… what is a METAR? It stands for “Meteorological Aerodrome Report” and is a coded message that most airports have, letting pilots know about the current weather at the airport. Bacially, it’s a weather channel for pilots.
Here is an example of a METAR:
LFPG 061930Z 04008KT 010V080 CAVOK 20/06 Q1025 NOSIG
Wait… what even is all of this??
Let’s decode it together.
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LFPG = The ICAO code of an airport (in this case, it’s Paris Charles de Gaulle airport)
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061930Z = The time in Zulu timezone. In this case, it’s on the 06th day of the month, at 19:30 zulu time (21:30 local time).
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04008KT = The wind. It is coming from 40° (North East) and is going at 8 knots (measure of speed in aviation).
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010V080 = The variation in the wind. This means that the wind can change direction and can be coming from anywhere between 10° and 80°.
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CAVOK = Ceiling And Visibility OK (Means that it’s a clear, blue sky and a nice day to fly).
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20/06 = The temperature is at 20° (C) and the dew point is at 6° (C).
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Q1025 = The QNH measure pressure which is currently at 1025hPa (HectoPascals, a measure of pressure).
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NOSIG = No Significant Change (This means the weather is not predicted to change anytime soon so if you’re flying in the area you should be good for now).
Of course, METARs come in all different shapes and forms, from each different airport. You can check them out at Windy.com to practice decoding them. Here are a few key terms found in METARs that can help you practice:
BKN = Broken clouds
BR = Mist
CB = Cumulonimbus
DSNT = Distant
DZ = Drizzle
FEW = Few Clouds
RY = Runway
SH = Showers of Rain
TS = Thunderstorm
WND = Wind
Metars are updated hourly.
Have fun :)
Pattern Work
Pattern Work is something aircraft do to practice landings and takeoff procedures. There are different stages in a classic pattern, such as crosswind, downwind, base and final. Here is an illustration to better show what a pattern looks like:
If you took off and turned left or right, you are on crosswind. Turn again, and you are parallel to the runway. This is called downwind. Turn again and that’s base. Finally, when you are aiming at the runway, that’s final.
A little demo: If the twin engine airplane in the image above was to contact ATC, they would say:
“Registration” is on left downdind runway zero nine, inbound for (whatever they want to do).
QNH
QNH stands for “Question Nil Height”… wait what does that mean again?!?
Basically, QNH is the air pressure (barometric pressure) which is adjusted to the sea level. That’s all it is, really. It’s a pressure setting used by ATC, pilots, etc to refer to the barometric setting which will allow the aircraft to determine the altitude above the average sea level.
Runway Numbers
You probably noticed numbers on the end of runways, but what do they mean?
These indicate the direction at which the runway is heading. Basically, if you were to align yourself with the runway, you would face that direction. However, for them to all fit in 2 digits, they were rounded by fives and divided by 10.
If the runway is at a 270°, the number will be 27
If the runway is heading at 359°, the number will be 36.
If the runway is heading at 8°, the runway number would be 01.
How about a runway at 05°? It is rounded up to the next tenth so it would also be 01.
L, C or R after a runway mean Left, Center and Right if there are multiple parallel runways. There are some exceptions in large airports such as LAX where runway numbers change a little bit but it’s an exception and not found commonly.
Taxiway Lines & Markings
When taxiing at an airport, you will see a lot of different lines and markings on the ground. Here are what each of them mean and what you should do with each.
A - Taxiway centerline - A solid yellow line that can be found on the center of taxiways. The purpose of this line is to guide aircraft. You must follow this line by keeping your nose gear centered on it.
B - Taxiway edge lines - These are on the edge of each taxiway… just don’t cross them and you won’t end up in the grass, it’s that simple :)
C - Hold short line - Found at certain airports in front of the runway. These consist of two solid yellow lines and two dashed yellow lines (some have black backgrounds, some don’t). These are used for safety to avoid collision between aircraft on the runway. You must stop at this line and keep your nose above it when waiting for takeoff clearance. If ATC tells you to hold short, keep your nose above this line. If ATC tells you to line up and wait, you must go onto the runway, center yourself and stop there so you are ready for takeoff.
D - Non-Movement line - This looks like half of a hold short line (one solid yellow line and one dashed yellow line above it). These show the limit of where aircraft can move before having to contact ATC. These are usually around ramp areas where aircraft and ground vehicles live in harmony. If you venture past this line, you must contact ATC as you will be on a taxiway.
E - ILS Critical hold line - Two parallel solid yellow lines interweaved with sets of 2 solid yellow lines going in the opposite direction. These are to be used as hold short lines when instructed to use them specifically or when ILS is in use during Instrument Landing Conditions.
F - also a taxiway centerline, but a different format. Use it the same way as a taxiway centerline (A).
G - Roadway centerlines - Dashed white lines used in the center of roadways, to mark each roadway’s width. Do not drive on these, you are not an airport vehicle.
H - Roadway markings - Solid white lines used to mark roadways used for airport vehicles. Do not drive on these, you are not an airport vehicle.
The Phonetic Alphabet (Alpha, Bravo, etc.)
Pilots and ATC communicate with weird terms, you might have seen that on IF already. The phonetic alphabet is a way to tell letters apart despite radio issues and static. If I’m talking to the tower and say my registration is “N31LN”, they might hear it as “M31LM” or something different. This is where the phonetic alphabet comes in. Instead of “N31LN”, I will say “November Three One Lima November” to prevent any confusion. Here is the full alphabet for each letter:
Alpha
Bravo
Charlie
Delta
Echo
Foxtrot
Golf
Hotel
India
Juliet
Kilo
Lima
Mike
November
Oscar
Papa
Quebec
Romeo
Sierra
Tango
Uniform
Victor
Whiskey
Xray
Yankee
Zulu
Vortices & Wake
When an airplane flies through the air, it creates drag. This drag is invisible most of the time however it can be seen in humid environments in the form of vortices.
Vortices are the turbulent air that remains behind an aircraft when it travels. Vortices, as beautiful as they can be, are also dangerous.
Large aircraft flying through the air create “wake”. This is the large amount of air being moved by the plane, and this can be dangerous for other aircraft. The bigger the plane, the more wake it creates (usually). However, since this wake is turbulent air, it can pose a threat to aircraft behind or under it.
This is why light aircraft must land a few minutes after larger aircraft. Although wake turbulence is invisible, it can be heard, and it will stay in the air for a long time after the aircraft passed.
If a small plane flies through a larger plane’s wake, it can cause the small plane to flip over and crash in a matter of seconds. This has led to multiple fatal accidents and is always something pilots and ATC need to remain aware of.
Please note that wake and jetblast are not the same thing.
The white trails behind these aircraft are vortices, representing the turbulent air behind them.
23/08/2022 there are 17 explanations
This is meant to keep growing, there will be more added when I think of more or when somebody asks.
Of course, if you have any questions, feel free to ask below. This is a wonderful community full of passionate, kind people who love aviation and if I can’t answer your question, you can be sure to find a specialist in the field who will be willing to help.
There are no bad questions, ask away and I’ll answer questions and add definitions as time goes.
Thank you all for making this such a nice community, and I hope to see you in the skies!
Have a nice day!
I hope this helped 😊
Robertine