Questions tagged [altitude]

A measurement of vertical distance. Usually measured at either Mean-Sea-Level (MSL) or Above-Ground-Level (AGL).

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How does cabin pressure vary with respect to ambient pressure during descent?

I came across this statement in a book - "During a descent, the cabin pressure in a pressurized aircraft usually climbs at as lesser rate than ambient pressure". Could someone explain this statement ...
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What is transition altitude?

Now I know the definition of transition altitude - it's the altitude where pilots change their barometric altimeter datum from regional pressure setting to 1013.2hPa. In USA the TA is 18,000ft. But I ...
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Is there a difference between altitude and flight level? [duplicate]

I came across a question in Quora asking the difference between altitude and flight level. One of the answers said that anything above the transition altitude is referred to as a flight level. So ...
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Why do aircraft fly so high? [duplicate]

Now I know aircraft fly over 30,000ft for the following reasons -less air resistance (less drag) hence more fuel efficient ,no need to worry about any weather related events and to avoid skyscrapers ...
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How does an aircraft descend without its nose pointing down?

I have seen many cockpit videos of airplanes landing, and nearly none of them have their nose down for losing altitude. How does this happen? and how does an airplane, such as A320, descend without ...
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Why is ISA Standard pressure 1013.2 not used for contour charts instead of QFF?

I am confused because QFF being actual mean sea level pressure is subject to change why would we use it for mapping terrain? Does this mean the height of a given terrain changes with the change in QFF?...
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Is there a database from which I can retrieve the Expected Crossing Altitudes of a Departure or Arrival Procedure?

I am stuyding FAA's Coded Instrument Flight Procedures (CIFP) file which uses ARINC 424 digital format to code its data. I noticed that only mandatory crossing altitudes and speeds are included in the ...
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Which altitudes are safest for VFR? [closed]

As a fairly new pilot who does a fair amount of x-country flying I find myself "feeling" safer going East at 5500 and West at 6500 happily burning extra fuel to get up there. Listening to the on route ...
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118 views

How is the total drag variation with velocity related to altitude?

Here in the question given I am confused how to relate the altitude with the given plot of total drag and velocity.
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Why does the spool speed increase with altitude for a turbofan engine (single spool & double spool)?

So, I want to see the effect of altitude on the compressor characteristic of a single spool & double spool turbofan engine at constant flight speed and TIT (turbine inlet temp). I am aware that ...
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Why is the B737 altitude display unneccessarily ambiguous?

I was playing FSX again lately and was flying the B737-400. So I hope it is simulated correctly and this question isn't dead on arrival :-) It always bugged me, that the altitude display on the MFD ...
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How do altimeters cope with varying lapse rate?

How do barometric altimeters measure altitude above atmosphere datum if the laps rate of the pressure is not uniform, not constant? Imagine these lines representing pressure lapse rate: ...
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How do flight procedure designers decide when to assign an altitude constraint to a waypoint?

I am studying procedure design manuals (TERPS, PBN 8260.58A manual, ICAO PANS-OPS 8168 manual etc.) and I haven't found any guidelines concerning altitude constraints that can be imposed on a waypoint....
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What is the limit between lower and higher airways in VFR?

On skyvector you see "World high", "world low" and the VFR map. VFR is always under the clouds, correct? But how high do you have to be to follow the high/upper and how high for the low/lower airways?...
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Why cruise at 7000' in an A319?

I was on a flight from Philadelphia (KPHL) to Boston (KBOS), after some delay and some change of route due to weather, the captain announced that we will be cruising at 7000' due to delays in the area....
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Is the transition altitude around Denali still 18 kft AMSL, and, if so, how is this handled?

In North America, the transition altitude - the altitude below which everyone reports their altitude in feet above mean sea level (AMSL) and sets their altimeter to whatever the weather dictates that ...
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How is paint embrittlement countered in high altitude aircraft?

There are cases of aircraft that are not designed for high altitudes that can still fly there and as a result the paint on these aircraft "falls off". Although most aircraft have paint that is chosen ...
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191 views

Why is True Altitude calculated using the difference from the QNH to 1013hPa?

I have an example for true altitude calculation. The given Information is QNH: 983hPa, cruise in FL 85, ISA -10°C in this Alt. The math and calculations are not hard and i also get to the correct ...
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Why use turbofan engines for high altitude flight?

I noticed that a lot of high altitude aircraft have turbofans for engines. So I researched and figured out that turboprop engines are more efficient. But most high altitude aircraft like the Global ...
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1answer
151 views

How do changes in flight affect L/D max and the speed at which I must travel to maintain it?

I have an plane flying at L/D max and I want to maintain L/D max. Firstly, if this plane burns through a portion of fuel and becomes lighter, how would I have to change the speed to maintain it? My ...
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249 views

What is the highest a helicopter can fly?

What is the highest theoretical and current flight a helicopter can achieve?
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Why does V165 have two different MEAs over the same route section?

Why does V165 have two distinct MEAs which vary by a large factor (apart from the 180$^{\circ}$ rule of altitudes) considering they would be clearing the same obstacles and receiving signals from the ...
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Identify a change in Altitude based on direction and WCA applied?

Question below is from study material for the EASA PPL license MET course. It's an unlikely question but it's interesting to review. You are flying from west to east with WCA +6°. How is your true ...
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Why does the Hinch Mountain VOR (as an example) have void areas under certain altitudes published in the AF/D?

I was digging around the SE region AF/D, and I was reading KSRB (Sparta, TN), and this "VOR unusable" listing is contained in it: The sectional chart shows that it is nearly on top of a hill. I've ...
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How is The Published Runway Touchdown Zone Elevation Decided?

The touchdown zone of a runway can be up to 3,000 feet long if the information I have is accurate. How is the published Touchdown Zone Elevation determined? Is it the center, an average of the ...
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How can I estimate pressure altitude?

How do I find pressure altitude? Find pressure altitude using rule of thumb for 1498 feet when the altimeter setting is 27.83" Hg. I did (29.92-27.83)*1000+1498=3588 Did I do this correctly?
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Calculation QNE and QNH, with flight level and QNH set lower (higher) than QNE

Hi Student pilot here. Lets say Mr pilot is flying at FL75 and QNH is set at 995 hpa, however there is a mountain in the way at 7000', will he below or above the mountain? If you could visually ...
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Is there a way to code Minimum Enroute Altitude using ARINC 424 file format?

I am studying ARINC 424 file format, and I have noticed that there is not any reserved space for coding Minimum Enroute Altitude (MEA), as far as Instrument Flight Procedures are concerned. I find ...
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How can I figure out critical altitude?

In Vmc situation (minimum speed where pilot can maintain altitude), How can pilot figure out the Vmc? And also, why critical altitude is important to know?
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What is the critical altitude?

What is the definition of critical altitude and why is important to know in Vmc graph? Also, is there any critical altitude in the Piper PA-44 Seminole?
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How are altitudes handled with airports near or above transition altitude?

Transition altitude refers to the altitude above which all altimeters are set to a standard pressure setting (typically 29.92 inHg) instead of to the local surface pressure, and altitudes are given in ...
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169 views

Wind vs high altitude cruise [duplicate]

Yesterday I flew back from Tokyo down south against great head wind around 150kt at 34000’, the original flight plan was to cruise at FL240 for a while then climb up, but the captain decided to get up ...
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How much the true altitude will be lower than indicated altitude by 10°C colder?

Aproximately how many perecent the true altitude will be lower than your indicated altitude , if the temperture is 10°C colder than standard ?
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How do pattern and overflight altitudes work for airports underneath Class C airspace?

Lowell City Airport (24C) has an elevation of 700 feet MSL. So normally, the pattern altitude is going to be 1,700 feet, and the altitude for overflying the pattern is going to be 2,200 feet. However,...
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393 views

Is there research suggesting that VFR cruise altitude rules improve safety?

In the United States, 14 CFR 91.159 prescribes cruising altitudes for level flight under VFR: (a) When operating below 18,000 feet MSL and (1) On a magnetic course of zero degrees ...
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Was the transatlantic crossing for Concorde too short to reach optimal cruising altitude?

When listening to Gander/Shannon ATC on shortwave, you could hear Concorde communicate its planned flight levels at longitudes from 20 West till 50 West. What I remember is that it would continue ...
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Is vertical separation based on geometric difference or altimeter difference?

In the comments below one of the answers to this question about the influence of temperature on vertical separation, the question was raised whether ATC ensure 1000ft vertical separation based on ...
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Why is 0 ft a valid target altitude for an autopilot?

Inspired by this story; The pilot of a Flybe plane that dropped 500 ft (152m) in 18 seconds had selected the wrong autopilot setting shortly after take-off, an inquiry has found... ...The ...
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What's the difference between flight level and pressure altitude?

When should we say flight level and when should we say pressure altitude? I know they both set QNE 1013.25, but there is a difference between them. Anyone know?
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Maintaining straight and level altitude [duplicate]

just a completely random question that I suddenly thought - doesn't straight and level flight prove that the earth's surface is not a globe? Once cruising altitude is reached, the plane remains at the ...
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Why can't I ever get my right ear to pop on descent in a plane?

Whenever I'm flying, there's a period of descent where my right ear just refuses to pop. This has been bothering me for at least ten years. There seems to be a long stage of descent where my ear is ...
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Is there a rule of thumb for reading AGL vs MSL? [closed]

Recently, I read that as it pertains to directions: if you read it, it's true, if you hear it, it's magnetic. This is mostly correct, one edge case though is runways are written/drawn with magnetic ...
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Why would a plane drop 14.000 ft mid flight?

Just noticed American Airlines flight 221 dropped 14.000 ft mid flight today. Curious, what could have caused this? Here are the flight details.
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771 views

Why do planes fly so high? [duplicate]

It so occurs to me that commercial airliners cruise at altitudes of over 30,000 feet. But why do they fly so high if there are many dangers such as cabin de-pressurization when they can simply fly ...
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382 views

Calculating the maximum altitude of a drone [duplicate]

Is there an equation to find the maximum altitude that a drone or quadcopter can fly to ?
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486 views

Can a commercial aircraft theoretically reach 60,000ft? [duplicate]

As per this question: Altitudes above 60,000 feet are class E airspace. That means that, if you are lucky enough to have an aircraft that flies that high, once you get there you could ...
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Why would a Mode-C transponder report a different altitude than an altimeter/GPS?

This is related to a small single-engined plane. On a recent flight, the controller kept telling me that I was 300 ft higher than it appeared on my altimeter and GPS (which were in sync). This was ...
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How much air does a GE90 ingest at sea level and at cruise level per meter?

I just wanted to know how much air PER METER a GE90 turbofan engine sucks in considering the same thrust output at different altitudes to better understand how the engine can travel further while ...
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What does it mean when ATC says “altitude indicates”?

I've noticed that ATC sometimes calls out traffic (a traffic advisory?) to aircraft using the "altitude indicates" phraseology, and sometimes a specific altitude is given without the phrase "altitude ...
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What are Altitude, Attitude and Heading Hold?

Can someone give a good and simple explanation about these three dynamics? Altitude Hold Attitude Hold Heading Hold