Questions tagged [terminology]

For questions about words, phrases and definitions that are specific to aviation or used in a different way in aviation.

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27
votes
2answers
114k views

What is the difference between centre of pressure, aerodynamic centre and neutral point?

I have just started learning some aerospace concepts, and I am not able to understand the difference between the three terms centre of pressure, aerodynamic centre and neutral point. What are their ...
9
votes
3answers
2k views

Is induced drag essentially nothing more than a specific type of form drag?

If I were standing outside on a windy day holding a flat rectangular object such as a food tray up in the wind, orthogonal to the direction of flow, the drag created would be classified, mostly, as ...
43
votes
3answers
159k views

What are the differences between Bearing vs Course vs Direction vs Heading vs Track?

This answer from English.SE does not focus on aviation, and does not explain 'Track'. In basic, simple English, would you please compare and contrast all 5 terms in my question's title? The ...
37
votes
3answers
69k views

What is the difference between “flight level” and “altitude”?

I have seen references to "FL180" and "FL300", and I know that they stand for Flight Level 180 and Flight Level 300. I've also seen references to "an altitude of 18000ft" or "an altitude of 30000ft". ...
24
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5answers
76k views

What does the term “trimming” most commonly mean in aviation?

Why does an airplane need trim, and what does it do during the flight? Does an autopilot adjust the trim automatically?
4
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1answer
13k views

What's the difference between FMS and FMC?

What's the difference between FMS (Flight management System), and FMC (Flight management computer)? Can the flight management computer be thought of as what's manipulating the input information from ...
16
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4answers
8k views

What is a canard?

While browsing this Stack Exchange, I regularly come across mentions of canards. I am not familiar with this term, and Google only gives information about ducks when I search for "canard". So, what is ...
5
votes
3answers
13k views

What is a flat rated engine?

I've heard that a "Flat Rated Engine" is an engine where the power is reduced to keep the internal temperature within certain limits when the ambient temperature is above a certain point. Is that ...
9
votes
2answers
6k views

Where does the term 'steam cockpit' come from?

Why are traditional style cockpits with gauges called 'steam cockpits'? Do the instruments actually run on steam?
20
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1answer
20k views

What is the difference between aviation “accident” and “incident”?

When I hear speaking about aviation crashes, sometimes I hear about "accidents" and other times about "incidents". What distinguishes them? Is there an international standard that determines how ...
14
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3answers
8k views

What is the name of the maximum altitude at which a helicopter can fly?

What is the name of the maximum altitude at which a helicopter can fly? I recall it as "vertical limit", but I can't find a Wikipedia page for it other than a movie of the same title, which seems to ...
1
vote
6answers
438 views

Why is a reduction in lift called 'drag'?

Induced drag is high pressure air 'leaking' to the upper part of the wing (low pressure zone) creating a vortex which means the area of the wing tip with the vortex can't create lift. Drag on the ...
17
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1answer
10k views

What is the difference between “sensitive” and “non-sensitive” altimeters?

In this answer reference was made to "sensitive" and "non-sensitive" altimeters. What is the definition of each, what are the differences, and why would one be used in preference to the other? And ...
6
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4answers
2k views

Does the expression “stall speed” have a definition?

I read, not only on this site, that the stall speed of an airfoil doesn't exist, and I usually make the effort to stay away from this expression. While an airfoil can stall at any airspeed, it's ...
10
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2answers
2k views

Is there a name for the area for aircraft to back track near the runway threshold?

Some airports have an area, on the threshold, used to back track the aircraft, mainly because of the their wingspan, they look like a half wheel. Is there any designation for this area?
7
votes
2answers
20k views

What is the difference between Cruise and Service ceilings?

I am looking at aircraft performance data. There are charts for "Cruise Ceiling" and "Service Ceiling." What is the difference? (The cruise altitude is lower.)
3
votes
1answer
79 views

How common is it in current British usage for the angle between the chord line of a wing and the flight path to be called the “angle of incidence”?

In American usage, the angle between the chord line of a wing and the flight path is called the "angle of attack". The angle of attack is also represented by the greek letter "alpha". However, some ...
14
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3answers
34k views

What is the origin of the term “pax”?

Pax in commercial transport is used as something like persons or passengers, in the context of counting people, e.g. 150 pax onboard. (Amadeus capture, source) I observed that in German writers tend ...
16
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1answer
2k views

When buying airliners what is the difference between “orders”, “options” and “purchase rights”?

I've often seen announcements by aircraft manufacturers or operators along these lines "Qantas announced today that they will buy 10 A380's and have taken options on another 10". What does it mean to ...
4
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3answers
2k views

Why does the Trent XWB have intermediate compressor stages?

I realized that the Rolls-Royce Trent XWB on the Airbus A350 has intermediate compressor stages. Why is that? Other engines like the CFM56 or IAE V2500 that power most of the A320-family have low ...
3
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1answer
758 views

What does leading edge radius mean?

What does leading edge radius mean amongst these parameters of a st cyr 24 airfoil?
18
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6answers
4k views

What would be a technical or slang term for 'in the air'?

I'm writing a sci-fi story involving aircraft and space craft. I'm struggling to get the terminology right for referring to a pilot being 'in the air' either on a mission or a training exercise. I ...
6
votes
3answers
1k views

Jettison and Dump fuel - Do they have separate meanings?

According to the definitions, is there any difference between Jettison and Dump fuel? Does one of them use a different procedure, or they are simply synonyms?
19
votes
2answers
17k views

What is the difference between a fix, a waypoint and an intersection?

It seems these terms are used interchangeably. Are they the same thing? Do they all refer to the points in space that are given 5-letter names?
37
votes
2answers
14k views

What do jet pilots say during the takeoff as they are speeding down the runway?

I was watching a documentary on youtube and the pilots always say something that sounds like "B1E" when they have enough speed to take off. What exactly are they saying, and why do they say it?
16
votes
3answers
36k views

What is the difference between GPS, GNSS and RNAV?

I would like to know the fundamental difference between GPS, GNSS and RNAV. How are they related each other? Are all/some of them synonyms?
42
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4answers
18k views

Why is the autopilot called “George?”

The autopilot of an airplane is frequently referred to as "George" (for example, in this answer). When did this nickname enter common usage, and what is its origin? Please cite sources if possible!
19
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1answer
7k views

What is the difference between fail-safe and fail-soft?

I have heard the following terms related to safe system design but I cannot really see a difference between fail-safe and fail-soft (graceful degradation). To get a common understanding I will just ...
17
votes
2answers
22k views

What exactly is a QRH?

In this question about aircraft dumping fuel I was told that there may possible be guidance in the QRH. I know that there are a lot of guidelines given to pilots, but I've never heard of this one. ...
22
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5answers
16k views

What exactly do “captain”, “pilot”, “co-pilot” and “first officer” mean?

I know the co-pilot sits beside the pilot. But it's not clear for me, who is the captain and who is the first officer? And where they are sitting during the flight? Who is in right seat and who is in ...
13
votes
1answer
1k views

Is GOCE a satellite or aircraft?

This vessel (GOCE) is in orbit and maneuvers by using air similar to a plane to create lift and turn. The solar powered ion thrusters powers it continuously inside the atmosphere for years. Is this ...
6
votes
5answers
15k views

Why is port-starboard terminology used in aviation?

I am not a pilot - just a student & play Ace Combat sometimes Intrigued by the words Starboard & Port-side I researched why these words are used instead of the simple ones, I found that: ...
5
votes
2answers
2k views

What, exactly is “on the MEL”?

The MEL, minimum equipment list, defines whether fault of some equipment on the aircraft prevents it from being dispatched for flight or not. However, sometimes (e.g. in comments to this question) ...
48
votes
4answers
9k views

What is a running rabbit?

My father used to work as an air traffic controller, and often I heard mention of a 'running rabbit'. Obviously, vermin on the runways of airports can be a bad thing, but I don't think he was ...
27
votes
7answers
7k views

At what point does an aircraft become an airliner?

For me, the term 'airliner' conjures up an image of a passenger jet that is capable of hosting a large number of passengers¹ but I'm finding it difficult to source a reputable definition or etymology ...
23
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3answers
3k views

Why is the “Dutch” roll called so?

Why is the "Dutch" roll called so? When did this name enter common usage, and what is its origin? Please cite sources if possible!
19
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2answers
6k views

Why do we call it a ramp?

Airport ramps are close to level, not inclined. What is the history and etymology of this aviation term?
15
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4answers
50k views

What is the difference between a nacelle and a cowling?

I see these terms used almost interchangeably. To my understanding they both refer to the covering of an engine. Is there a technical difference between the two?
15
votes
3answers
6k views

What's an “altitude engine”?

FAR 91.205(b)(8) says that you need a manifold pressure gauge for each "altitude engine", whatever that means. What's an "altitude" engine?
14
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3answers
3k views

What does “out of trim” mean?

Our flight was delayed from takeoff because the captain reported it to be "out of trim". What does this mean?
13
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1answer
1k views

What is an airliner's “green dot speed”, and how does it vary with weight, and why?

A related question told us, quoting from an Airbus performance manual, Green dot speed (minimum gradient) is a function of weight. Comments under the question stated that the "green dot speed" ...
2
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4answers
4k views

What is the relationship between Angle of Attack and Angle of Incidence?

The Angle of Incidence (AoI) of most GA planes is 6°. Assuming a plane with an Angle of Incidence of 6 degrees-- How do we calculate pitch attitude if we know the direction of the flight path and the ...
2
votes
1answer
1k views

What is the difference between Fly-By and Short-Turn?

By all definitions that my team and I have found, fly-by and short-turn (with respect to military unmanned air vehicle waypoint based flight) mean the same thing. Briefly, this allows the pilot to ...
1
vote
1answer
159 views

What is an “unsafe airline”? [closed]

Question: Is there any internationally accepted definition for what an "unsafe airline" is based on objective criteria (e.g. fatalities per million passengers) ? Or is there an international standard ...
21
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3answers
14k views

What are the differences between various simulator levels?

I've heard of level A, B, C, and D simulators, (as well as FTD and AATDs) but know nothing about them. What criteria is used to certify a sim as a particular level?
16
votes
3answers
8k views

Why is it called “Dry Thrust”?

When reading the specifications of a jet aircraft anywhere on the Internet, it usually states that its engine produces X pounds of "dry thrust". Why is it called "Dry" Thrust? As opposed to what?
14
votes
6answers
11k views

Are “Tally-ho” and “no joy” acceptable ATC terms for civil operations?

I keep meaning to ask this question. I heard "Tally-ho" used for the first time by a pilot on Liveatc.net. I know these are pretty standard phrases in military aviation but I wondered if civil pilots ...
11
votes
2answers
8k views

What is the true meaning of the word “roger” when used on the radio? What is its origin?

When pilots learn to talk on the radio they can generally learn that the word "roger," when used on the radio, is a way to acknowledge that a message was received. What is the textbook definition of ...
10
votes
1answer
368 views

In the United States, are ultralights legally considered aircraft?

I sometimes hear it stated that in the United States, ultralight vehicles are not legally considered to be aircraft. For example, Wikipedia used to state: In the United States ultralights are ...
10
votes
1answer
1k views

What is Flexible Gunnery in the US Air Force?

I read many times in English Wikipedia that some servicemen were trained in Flexible Gunnery schools, but I don't get what that exactly means. Example: In January 1942, the 2d Air Force was ...