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Questions tagged [flight-instruments]

Flight instruments provide the pilot with information about the flight situation of that aircraft, such as altitude, speed and direction; and are of particular use in conditions of poor visibility, such as in clouds, when such information is not available from visual reference outside the aircraft.

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456 views

What is the difference between a “compass swing” and “check swing” procedure?

What is the difference between a "compass swing" and a "check swing" procedure?
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3answers
4k views

What was the first flight instrument ever used in an airplane?

It's not magnetic compass, turn coordinator, stopwatch, wind meter, VVI, and airspeed indicator. I want to know what is the first flight instrument.
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663 views

What are the differences between ADS + INS and ADIRS / ADIRU?

What is the main difference and advantage in the Air Data System, between the former architecture (ADS + INS) and the newer one (ADIRS/ADIRU)?
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955 views

What is Engine Pressure Ratio?

I kind of know what it is but I don't fully understand it. Wikipedia says, the engine pressure ratio (EPR) is the total pressure ratio across a jet engine, measured as the ratio of the total ...
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156 views

In the ARINC specification, why is baro altitude (label 204) measured in Knots?

I am currently designing a system that reads the baro altitude (on label 204) from an LRU. Ultimately in my software I would like to display the baro altitude reading in real-time using a graphical ...
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1answer
477 views

How does an engine driven vacuum pump used in gyroscopic instrument work?

In general aviation light airplanes (C152,C172,PA28..) how does the engine driven vacuum pump work?How is it made? and if the filter of one of the gyro instrument is clogged would the vacuum ...
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2answers
349 views

Is there any instrument similar to a compass but which I can electrically drive?

I would like to build a home weather station with analog instruments showing for example temperature, wind speed and wind direction. I would like to use a salvaged flight instrument to show the wind ...
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173 views

What is the correlation between RNP level and the CDI indication?

I got a question regarding the connection between RNP (required navigational performance) accuracy and cdi sensitivity of the HSI. According to the instrument flying handbook the standard for RNP on ...
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2answers
991 views

What navigational aid(s) would WWII bomber pilots have used while flying in instrument conditions?

In my furthering attempt to understand the accident mentioned in this post, I've become interested in how WWII Bombers would have flown on instruments. In the accident report, the pilots states: ...
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1answer
126 views

Would fuel quantity indications be affected by extended flight at nonzero bank angles?

If flying with a 20kt crosswind requiring yaw input as well as roll input to maintain course, would the fuel indicators show different loads depending on the roll angle of the aircraft (in this case, ...
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2answers
241 views

Measuring speed and altitude from personal phone midflight [duplicate]

Given that there is no need now for one to swith off their cellphone midflight, inflight wifi is now a norm and common, Is it possible for me to measure the velocity and altitude of an aircraft using ...
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1answer
201 views

Are GPS airspeed meter and altimeter going to replace traditional measurements?

When are GPS Airspeed meters and Altimeters going to be introduced if they not already in use? Are they more accurate than systems in use now and? How much would it cost to install them to older ...
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1answer
560 views

Are there benefits in training instrument students how to fly a DME arc?

With more instrument approach procedures being designed for RNAV/GPS equipped aircraft, and considering the high level of radar coverage currently available, is there a need to spend much valuable ...
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1answer
3k views

What do the yellow lashes/wings on the B737 PFD indicate?

When I was looking at a YouTube clip of a B737 doing a landing, I couldn't help but notice something on the PFD: What do these yellow lashes/wings indicate on the artificial horizon? Image Source (...
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1answer
514 views

How do instructors simulate instrument failure in basic training aircraft with glass cockpits?

While working towards my private pilot's license in the United States in 2004-2005 (in a steam gauge only airplane), I very much remember my instructor covering one or more instruments to simulate ...
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What prevents a Machmeter from being the standard airspeed indicator?

Airspeed is more accurate when displayed by a Machmeter than when displayed by an airspeed indicator. It isn't affected by ambient temperature / density changes. It is still affected by position error,...
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How does an Airbus pilot decide whether to use HDG-V/S or TRK/FPA guidance?

The Flight Control Unit of modern Airbus aircraft has a pushbutton for selection of either heading / vertical speed (HDG-V/S), or track / flight path angle (TRK-FPA) guidance for the Autopilot and ...
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1answer
350 views

How should this Bendix course deviation indicator from the '50s be read?

This is a Swissair photo from a DC-7C panel. Source I have seen photos on airliners.net of these in DC-6s, VC-118 and Constellations. It appears that other companies besides Bendix made these ...
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1answer
2k views

Statute miles to runway visual range [duplicate]

Is there a formula to converting statute miles to runway visual range? If so, what would it be? I'm seeing how 1 mile is equal to 5000 feet, but I am so confused because 1/2 of a mile is equal to 2,...
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2k views

What is the difference between a pitot tube and a pitot-static tube?

What is the difference between a Pitot tube and a Pitot-static tube? If an aircraft fitted with Pitot tube and static holes on the fuselage, is it necessary to consider the static pressure ...
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3answers
3k views

What's the UX in modern airliner avionics for diversion choices, and does it integrate to autopilot?

This question mentions a flight that had to divert, in that case to Iqaluit (YFB). I was wondering: in modern large airliners, what is the user interface like when diverting? How is the case of "what ...
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1answer
1k views

What are the pros and cons of vacuum and pressure gyros?

Inspired by this question, I would like to know what the pro's and con's of the mostly used vacuum-gyro and the less used high-pressure-gyro is. Side-question: Are there any other ways to make the ...
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796 views

What is this nose cowl mounted display?

(YouTube) A crop duster's nose mounted display. It looks like a poor man's HUD to keep the display and the outside view at roughly the same focus distance, but what is its function?
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376 views

On an inverted aircraft, is the ILS glide slope sensing reversed?

If I'm halfway through a barrel roll on final descent, on an ILS, will I get reverse sensing on my glide slope indicator?
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1answer
87 views

Why $\frac{\Delta p}{\overline q}$ is depending by weight, flap deflection and other parameters? Which are other parameters?

As you can see in this link (Roskam, Airplane Aerodynamics and Performance, Chapter 2.5.3 Airspeed corrections) ... ... in the first and second line of page 30 Roskam tells that, in hypothesis of ...
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1answer
495 views

What caused the loss of “everything” on Swiftair Flight QY-2939?

I found this from a youtube video, and more info from this avherald article. One of the pilots declares an emergency because right after takeoff they lost "everything", as in all instruments. ATC ...
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1answer
515 views

At what altitude do vacuum powered gyros become ineffective?

Obviously, in space a vacuum powered gyro would not work because there is no air to move, but, how high do you have to go before they are unable to spin fast enough to work properly? would a vacuum ...
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1answer
178 views

What techniques, tools, or instruments are used while performing zero-g parabolic dives? [duplicate]

There are companies that sell "zero g" rides, where the aircraft is configured specifically to take people and possibly experiments through a parabolic dive to experience a short period of micro-...
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4k views

How can pilots lacking instruments interpret vectors given by ATC?

This video is about European Air Transport flight 2939, a Boeing 737, which "lost all the instruments of the aircraft" shortly after takeoff. BCS2939: We are flying heading now, and we don't have ...
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2answers
739 views

How does altimeter reading vary when departing from ISA conditions?

I am a soon-to-be student-pilot and am struggling with a basic concept that is altitude. After watching multitude of online videos, I feel that most of the people do not have good teaching skills. ...
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5answers
3k views

What will the pilot do if all the airspeed indicators fail?

Are there any alternate instruments to indicate the airspeed in case of pitot tube failures?
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2answers
616 views

What causes the phenomenon that pilots don't believe their instruments, while they're working well?

I read in a comment on another question that pilots not believing their instruments while they work perfectly well is common in aviation: The flight leader reported that his compasses had failed [.....
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1answer
509 views

Why vacuum instead of pressure to power gyros?

Why are most air powered gyro instruments powered by vacuum rather than positive pressure?
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1answer
267 views

How does Pitot Heat influence airspeed indication (assuming no ice or moisture)?

Should Pitot Heat ON (in dry weather conditions) decrease airspeed indication because warmer (so less dense) air flows through the tube?
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2answers
417 views

How does a Machmeter behave if the static port is blocked during a constant CAS climb?

Question: How will the machmeter behave in a constant CAS climb if the static source becomes blocked? Answer: The machmeter reading will decrease. Why? I couldn't find any logical reason for the ...
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2answers
2k views

What does it mean when pitch numbers move all over the HUD screen?

In this video from an F-16: You can see pitch angle move out of screen or be on the side at the end.
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1answer
1k views

How is the terrain displayed on the ND in a A320?

When you turn on "TERR ON ND" in a A320, you see terrain info on you navigation display (ND), but where does its source come from ? if data comes from FMGS stored inside its memory, then how come it ...
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1answer
407 views

Does an RMI show true or magnetic north?

Does the compass card of a Radio Magnetic Indicator (RMI) point to true north or magnetic north ?
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1answer
189 views

How do fighter jets measure how high they are?

I know most of the commercial planes use altimeter to find how high they are. I was just curious in finding out what fighter jets use to to find their height and what are the other technologies that ...
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13answers
10k views

How did planes measure their speed relative to the ground before GPS?

How did planes measure their ground speed before GPS? If they used some sort of anemometer to measure speed, that would only measure the speed of the plane relative to the air through which it is ...
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2answers
2k views

How is a conflict between aircraft with TCAS I and II resolved?

Let's say there are two aircraft in a risk of collision, one of them is equipped with Traffic Collision Avoidance System (TCAS) I so it will get only a Traffic Advisory (TA), however the second one is ...
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2answers
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Are turn and slip indicators calibrated to a certain speed? If so, what speed?

Are turn and slip indicators calibrated to a certain speed? If they are, What speed are they calibrated to, and why aren't all the turn and slip indicators calibrated for the same speed?
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2answers
532 views

What is the most accurate geometric plane for referencing terrestrial flight attitude?

I have found various definitions for attitude. Merriam Webster: inclination of the three principal axes of an airplane in flight to the relative wind. Wikipedia - Attitude Indicator: the orientation ...
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2answers
891 views

What type of altimeter is this?

What type Altimeter is an SA-91? It has three pointers 100, 1000, 10000. Don't know if it is Kollsman. I can't find any info as far as repairing unit.
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1answer
860 views

When do I need to worry about a course deviation indicator reverse sensing?

I understand that if I am tracking a radial inbound I will set that radial as the reciprocal so I don't have to worry about reverse sensing. On an approach however, do I need to set the CDI to the ...
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1answer
1k views

Why was the WWII RAF fighter joy stick loop design not used widely?

WWII RAF fighters had a loop on top of the joy stick in case of hand loss or injury - Anyone know why the Allies didn't copy this very helpful idea?
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3answers
283 views

How can I get General Aviation flight data on smartphone and/or tablet?

Is it possible to in-flight receive navigation data on an electronic device (like smartphone and/or tablet) present in the cockpit? I refer to General Aviation aircraft and navigation data like ...
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2answers
38k views

What are the differences between an OBS, a CDI, a Heading indicator, and an HSI?

What are the differences between an OBS, a CDI, a Heading indicator, and an HSI? As far as I can tell they all use VORs. Why would 4 different version of the same instrument be invented? Is the HSI ...
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1answer
292 views

What is the Boeing 727 AC Generator Panel Part Number?

Does anyone know the part number for the Boeing 727 AC Generator Drive panel? I have searched the Internet and have not found the part number. (Source)
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211 views

How do you set up your nav instruments and coms during ground operations and takeoff? [closed]

I have an HSI, an OBS, and a GPS. I normally set my HSI to runway heading, my bug to the wind direction, and the GPS to destination airport/waypoint (which will give me my turn out heading). I don't ...