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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30
votes
2answers
148k 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
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3answers
3k 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 ...
54
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3answers
179k 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 ...
38
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3answers
89k 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". ...
26
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5answers
86k 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?
6
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1answer
17k 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
10k 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 ...
8
votes
3answers
17k 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 ...
1
vote
6answers
646 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 ...
9
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3answers
3k views

What are E2 and E4 airspace?

We have a number of questions here about E2 vs. E4 airspace (see summary of links in this answer) but what does that mean? As far as I can see, neither the AIM nor the ATC Orders mention E2 or E4 ...
21
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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 ...
8
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2answers
8k 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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3answers
44k 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?
15
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2answers
52k 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 ...
17
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1answer
12k 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
3k 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
23k 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
109 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 ...
2
votes
3answers
244 views

Is there a standard word or phrase in the English-speaking world to describe the angle between the fuselage and the flight path / relative wind?

Is there a standard word or phrase, or several alternative commonly-used words or phrases, in the English-speaking aviation world to describe the angle between the longitudinal axis of the fuselage, ...
20
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1answer
9k 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 ...
16
votes
1answer
3k 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 ...
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 ...
11
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1answer
588 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 ...
5
votes
2answers
3k 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) ...
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 ...
26
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6answers
8k views

What is the difference between a flow and a checklist?

Use of checklists is a 'special emphasis area' during FAA private and commercial checkrides but there are a lot of comments in pilot forums about using flows instead, often - but not always - in the ...
14
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1answer
6k 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" ...
3
votes
1answer
984 views

What does leading edge radius mean?

What does leading edge radius mean amongst these parameters of a st cyr 24 airfoil?
2
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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 ...
18
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8answers
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 ...
8
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1answer
228 views

What is weight-climb speed?

I have a question about a document published by the Association of European Airliners. The name of the document is “Long Range Aircraft - AEA Requirements.” In the Appendix titled "Definitions and ...
7
votes
3answers
2k 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?
4
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2answers
12k views

What is the FAA definition of solo flight?

If I'm a student pilot (for commercial), and I flew for pleasure with friends one night, do I log those hours as solo? Does solo mean, only pilot in the aircraft? Or does it literally mean only person?...
20
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3answers
23k 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
15k 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?
17
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5answers
46k views

What is the difference between slice, segment and leg?

I have heard of the terms slice, segment and leg. Since I am a newbie in travel industry, I would like to know and understand the basic differences between the three. Could someone please explain ...
17
votes
2answers
23k 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. ...
41
votes
4answers
20k 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!
22
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5answers
20k 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
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1answer
2k 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 ...
9
votes
5answers
20k 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: ...
8
votes
6answers
6k views

What exactly is a "coordinated" turn?

I am wondering what turn coordination really means and what makes a turn uncoordinated? I know that when the turn is coordinated, there is no slip and skid, an aircraft is flying a perfect circle ...
48
votes
4answers
11k 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
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7answers
8k 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!
23
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3answers
4k views

What does the term "tanker" mean when used in regards to a passenger airliner?

In a comment on this answer: Airlines will tanker fuel if it's substantially cheaper at another airport I've wondered what that term meant before, and now this comment leads me to think that ...
19
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2answers
7k 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?
17
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3answers
8k 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?
16
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4answers
60k 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?