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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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How reliable are stick shakers?

I've read many accident reports, and seen reconstructions, where instrument failures, disagreeing sensor sources and auto pilot faults have led pilots into believing that they are over speeding when ...
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Can a vacuum cleaner create sufficient vacuum to operate the artificial horizon?

Inspired by this question about breaking the glass of instruments, I was wondering if a sufficient level of vacuum can be achieved by using a vacuum cleaner on the inlet, or simply sucking through a ...
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Can instruments be fixed via a swift punch?

I remember reading a book about private piloting techniques, (I can't remember the title; it has been so long; perhaps I can check my library history or something to see later), and I saw something ...
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How does an energy variometer work?

In a comment to an answer regarding instrumentation complexity, an "energy variometer" was mentioned, labeled in knots. What does this dial actually show, and how does it work? The image accompanying ...
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How is the pitot/static system of a helicopter affected by rotor downwash?

Since the fuselage of a helicopter is affected by downwash from the rotors, how is the pitot static system affected?
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2answers
642 views

What are the different variants of ILS intrumentation?

Background: I'm a huge aviation enthusiast with a lapsed PPL. Have flown some larger aircraft on MSFS, but never flown anything in real life bigger than a C172. I was lucky enough to do a bit of ...
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5answers
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Why is there a difference between GPS Speed and Indicator speed?

I just played with flight simulator and noticed that the GPS shows different speed from the speed indicator in the cockpit. Also, GPS speed is higher than the Indicator. Any Idea why?
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1answer
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When has China said it will mandate head up displays (HUD)?

I tried to google this but could not seem to get a clear answer. I was wondering because I heard they first mandated all aircraft by some date which was no where near realistic in terms of cost to ...
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Are modern aircraft provided with analog consoles in case of a software failure?

I am curious about the redundancy they provide in modern era commercial aircraft. Here are the questions: If an aircraft suffers partial or complete software malfunction, do the pilots have the ...
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2answers
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How precise are altimeters?

How precise and how accurate are typical altimeters these days? That is, if two planes are flying (side-by-side, very near each other), and both altimeters show the same Flight Level, what is the ...
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4answers
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What is the advantage of combining the rudder and brake pedals in aircraft?

I've read about several aircraft having their rudder and brake pedals very close together. To me this seems confusing and prone to error. It looks easy to mistake the rudder / brake pedals and ...
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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?
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Is the altimeter setting corrected for temperature?

In an ATIS or AWOS/ASOS recording, is the reported altimeter setting corrected for temperature? I think it must be, because on a hot day, the altimeter should still show correct field elevation. If ...
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Why don't both black boxes hold the same data?

As I understand, there are two black boxes on-board an aircraft. One black box, the Cockpit Voice Recorder holds the cockpit conversations and the other, the Flight Data Recorder holds essential ...
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3answers
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Where did the standard pressure 29.92" come from?

Below the transition altitude (18,000 feet in the US), pilots use local pressure readings to calibrate their altimeters. Above the transition altitude, pilots set a standard pressure to calibrate the ...
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2answers
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How does an alpha (AoA) vane work?

The alpha vane (also called AoA vane) is an external probe used to measure the angle of attack. I have been trying to understand how exactly it works, but I can't find any clear explanation or ...
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5answers
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Can the pitch be very different from the angle of attack?

How much the pitch (horizontal orientation) can differ from the angle of attack? I am trying to understand the claim that "angle of attack indicator was unfortunately not available", contributing to ...
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How does an A330 detect stall without airspeed?

On Air France 447 the crew had experienced complete failure of the pitot static system, which meant they lost their readings on their airspeed indicators, but according to the Mayday / Air Crash ...
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1answer
641 views

Can St. Elmo's Fire cause instruments to fail?

Can St. Elmo's Fire on an aircraft cause instruments to fail or give erratic readings, primarily with glass cockpits? Are there backup instruments that would not be affected? Does it affect radio ...
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How does a Mach Meter determine the speed of sound at a given altitude?

By my understanding, the Mach Number at a given altitude is calculated by dividing IAS by the speed of sound at that altitude. So how is this speed of sound calculated to display the Mach Number on ...
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Are solid-state attitude indicators subject to gimbal lock?

With all the shiny new glass cockpits it would seem that the days of the spinning mechanical gyro (and associated tumbling due to gimbal lock) should be over: Sparing everyone the boring math it ...
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1answer
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Are there any studies on the safety of glass versus steam instruments?

Has anyone come across any academic study on the effects of information provided by "glass" instrumentation that affects, favorably or unfavorably, situational awareness, skill and performance, and ...
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1answer
430 views

What kind of malfunction is an “artificial horizon”?

I was once (like ten years ago) on a transpacific flight with Northwest from KIX/RJBB to KDTW on a Boeing 747 and our flight as delayed at the gate for about an hour because of some issue with a "...
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4answers
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When/How may I replace the Turn Coordinator with an Artificial Horizon?

I've seen a few panel shots where the traditional turn coordinator has been replaced with a second artificial horizon, as shown below. The benefits seem obvious - if my artificial horizon failed I'd ...
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1answer
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What is the difference between OAT, RAT, TAT, and SAT?

When I first started flying jet aircraft, I found different instruments that measure temperature in different ways and it was quite confusing. What is the difference between Outside Air Temperature,...
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3answers
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Who decides what measurement units are used for altitude, and why is there no standard?

I know that some countries (Russia and China for instance) use meters to measure altitude while the rest of the world uses feet. Why isn't this standardized around the world? I guess all modern ...
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1answer
725 views

What instruments or avionics do balloons usually have?

For normal sightseeing flights in a typical hot air balloon, what instruments or avionics does the pilot usually carry? Do balloons have a minimum equipment list?
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Is IAS without instrument error the same as CAS?

I was reading a POH which stated something along the lines of NOTE Except as noted, all airspeeds quoted in this handbook are Indicated Airspeeds (IAS) in Knots and assume zero instrument ...
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Why don't pilots always use autoland?

In aeroplanes that are equipped for autoland and landing at an airport with a working and adequate instrument landing system for the conditions, why would a pilot choose not to use autoland? If I had ...
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5answers
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Why the pitot tube is heated but the static port isn't?

In some light aircraft, like a Cessna 172, the pitot tube is heated but the exterior static port isn't. The usual reason I've heard is that static ports are much less susceptible to icing, but why is ...
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1answer
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Why does the EGT gauge in 172s have no numbers on it?

So the EGT gauge on the 172 (and other cessna singles?) doesn't have a numerical scale on it, just markings every 25 degrees. I know that one is supposed to use the EGT for leaning operations (ROP, ...
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2answers
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What is the purpose of the string taped to the front of the canopy on gliders?

What is the purpose of the piece of string taped to a glider canopy? Is it effectively a turn coordinator, but then what advantages would it have over a gauge such as the ones fitted in powered ...
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5answers
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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?
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What's the difference between True vs Magnetic headings?

What is the difference between a true and a magnetic heading? Why are/were magnetic headings used in aviation?