Questions tagged [sensors]

Questions about various sensors used in aviation, both on aircraft and ground equipment.

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11
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1answer
1k views

What is this thing on a FDX MD11 (MD10?)?

I assume something forward looking; not sure why there and how they got this to play nicely with radar
2
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1answer
167 views

What is that sensor on the Airbus A220?

What is the that sensor in the picture?
0
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1answer
155 views

Why does an ADIRU 1 failure disable all functions of the A330/340’s GPWS - even those not requiring ADIRU data?

Among the many (many many) aircraft systems degraded or rendered unavailable to the flightcrew of QF72 as a result of a partial intermittent ADIRU 1 (Air Data / Inertial Reference Unit 1) failure, the ...
17
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6answers
6k views

Do aircraft have accelerometers?

Do modern aircraft employ accelerometers or other similar equipment to measure g-forces on the aircraft? I could imagine this being used as an inspection/service indicator, particularly after hard ...
1
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1answer
99 views

Why do most commercial solid-state Inertial Measurement Units (IMUs) measure angular rate and not angular acceleration?

The vast majority of MEMS-based IMUs are formed by an accelerometer and a gyroscope, providing linear acceleration and angular rate measurements respectively. However, having available the angular ...
6
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4answers
480 views

Why aren't angle-of-attack data sanity-checked before being fed to other aircraft systems?

For most fixed-wing aircraft, accurate angle-of-attack information is utterly essential for safe flight, due primarily to the risk of stalling the aircraft if the AoA of one or both of its wings ...
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0answers
39 views

How is the airflow controlled in a Total Air Temperature probe?

How does the so called "sonic throat" control the air flow in a total air temperature probe?
5
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1answer
295 views

What is GPS HIL in layman's terms?

GNSS Horizontal Integrity Limit/ Horizontal Protection Level is a measure of GNSS position error/integrity that's very important in RNP operations and RAIM, but it has an obtuse definition in aviation ...
1
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1answer
136 views

How many Angle of Attack sensor vanes should a commercial passenger airliner have? [closed]

The ill fated MAX of recent news had 2 angle of attack vanes, with the MCAS computer picking the worst one. It seems a "software patch" may not be the only improvement option available. Sensible ...
13
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2answers
3k views

Why are the angle-of-attack sensors on most airplanes mounted on the forward fuselage rather than at the wing roots?

A source of reliable angle-of-attack information is important for airplanes, as flight at an excessively-high angle of attack can cause the airplane to stall, which is generally considered to be an ...
2
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1answer
105 views

How do rate gyros and other sensors send information to the flight control computer in an F-16?

How do rate gyros and other sensors send information to the flight control computer in an F-16? I mean is it a hardwired communication or it is done through a bus? If by bus, what is the bus called? ...
7
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1answer
255 views

Why would there be airflow from the back of a TAT probe?

During walk-around checks, I occasionally find airflow coming out from the back of the TAT probes on the Airbus A320. I wonder if it's air to cool down the TATs as they are heated during flight for ...
5
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2answers
214 views

What sort of sensors are used for sensing the positions of the control surfaces for the ECAM F/CTL page on Airbus aircraft?

During the pre-flight flight-controls-check how does the ECAM F/CTL page report on the actual positions of the control surfaces? What sort of sensors are these? Is it a proximity sensor? This is ...
4
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1answer
106 views

How are sensors in the wheels connected to power and data buses?

In this question the sensors to measure the tyre pressure are described. But how do such sensors receive the electrical power they need, and how are the signal values transmitted back to the relevant ...
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0answers
33 views

Sample sensor data for AHRS

I'm working on developing Kalman filter code for winged aircraft AHRS. Does anyone know of any sample raw sensor data to use for development? Ideally it would include gyros, accels, magnetometer, ...
1
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1answer
81 views

What material and shape should be used for angle of attack sensors?

Does the material and shape of the vane for an angle of attack sensor have to be identical to the material and shape of the wing? What properties should I consider?
1
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2answers
377 views

Why are so many tail-strike incidents not verified until later inspection?

One often reads of a "suspected tail-strike" at take-off (for example suspected because a controller has seen something from the tower, or because a cabin crew member sitting at the back of the plane ...
0
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1answer
278 views

How much does an air data module cost?

Curious how much Air Data Module and Angle of attack sensor costs, such that is used on commercial airliners.
2
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1answer
211 views

How are AOA sensors tested after working on them?

If a maintenance or replacement has been done for an AOA sensor, would the mechanic be able to test if the sensor now works correctly? Can such a sensor be tested on the ground? If there is no ...
1
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0answers
89 views

Aircraft with load sensors in their undercarriage to calculate CG [duplicate]

In another question on SE aviation I read that certain aircraft have load sensors in their undercarriage to calculate CG. Which are these types? The technology to build load sensors into the ...
7
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4answers
812 views

Why do aircraft stall warning systems use angle-of-attack vanes rather than detecting airflow separation directly?

Stall warning and protection systems on essentially all aircraft work by using several hinged vanes on the side of the fuselage (usually at least three, and preferably more), which align themselves ...
5
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4answers
711 views

Why are the AOA sensors placed outside the aircraft?

Why should the AOA sensors be placed outside the aircraft? Is it not the angle between the chord line of a wing and a vector representing the relative motion between the aircraft and the surrounding ...
5
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2answers
3k views

what type of sensors does the Boeing 737 MAX use for MCAS?

I can imagine there are several different ways to measure angle of attack (accelerometers, relative pressure measurements between pitot tubes, etc), but I'm curious which sensors the 737 MAX uses for ...
15
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1answer
878 views

What were the advantages of the L-1011 AoA sensor design?

The Lockheed L-1011 had an unusual type of AoA sensor. Instead of the usual vanes it used a tube with two rows of holes in it about 90° apart. A diaphragm sensed the pressure differential between the ...
0
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1answer
1k views

Has the number of angle of attack sensors been reduced in Boeing 737 Max, in comparison to the older models?

Boeing 737 is flying since 1967. I would like to know first how many ' angle of attack sensors' does it have, and has they number been reduced for Boeing 737 Max, in comparison to the older models ...
15
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2answers
3k views

Why is not every airplane equipped with 3 angle-of-attack sensors?

For critical systems, redundancy is built into the system. It is common knowledge among designers/architects to have three different inputs so in case one is faulty, input from the remaining two can ...
9
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1answer
9k views

How many AOA sensors does the 737 MAX have?

How many AOA sensors does the 737 MAX have? Given that it's reported in the media, that one faulty AOA probe activated the MCAS on the Lion Air flight, I was wondering if anybody also knows how an ...
10
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3answers
501 views

Is it common for automated control systems to use non-redundant sensors?

While reading an article about the Lion Air Crash with a Boing 737 Max 8, I was very surprised by the following paragraph: In designing the 737 Max, Boeing decided to feed M.C.A.S. with data from ...
13
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2answers
2k views

What is this tube in a jet engine's air intake?

I have long been wondering what is the official name of this little air intake tube located in front of the fan blades and its intended functions. I did search it on google but it was in vain. I guess ...
6
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1answer
381 views

Why are the positions of an aircraft's angle-of-attack vanes dependent on airspeed?

According to this answer to an earlier question of mine, the positions of the angle-of-attack sensor vanes on the A330/A340 are dependent not only on AoA, but also on airspeed (and, according to @ymb1'...
5
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1answer
1k views

Will an Airbus A320 plane go into an unrecoverable nosedive and crash if a single angle of attack sensor fails, like on Lion Air JT610?

For example, has an Airbus gone from cruise flight into an automated unrecoverable nose dive until it hit the ground because an AOA sensor failed in flight? Moreso, are there any cases of an AOA ...
3
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1answer
282 views

Do airplanes have sensors to detect landing gear fires?

Given that retracting a landing gear that happens to be on fire is a suicidally bad idea, for reasons that should be immediately obvious, do airplanes have temperature sensors on their landing gear in ...
1
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2answers
111 views

How is an out-of-trim condition (in relation to weight distribution) detected on the ground?

My question relates to Captain reports Out of trim and this answer. How is an "out-of-trim" condition like the one mentioned in the linked question detected on the ground? I.e "out-of-trim" in the ...
1
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1answer
333 views

Which company manufactures the air data system on the Boeing 787-9 'Dreamliner'

I'm asking specifically about the manufacturer and model of the Pitot probes/tubes that provide the pilots with current air speed readings. Pretty sure it's either UTC or Honeywell but can't find ...
8
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2answers
564 views

What are those sensors on the forward A321neo fuselage?

What are those sensors on the forward (Airbus) A321neo fuselage? If it helps, this is WOW air's TF-DTR.
1
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1answer
141 views

What are heat detection sensors and how can they cause a speed error?

From this news article on Saratov Airlines Flight 703: A report handed down by Russian investigators has blamed human error for the crash of Saratov flight 703, saying the pilots didn’t switch on ...
8
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1answer
785 views

What additional functionality is provided by the F-14 nose pitot, absent in early models?

Early model F-14A had no nose pitot: ... but they seem to have quickly acquired them sometime in the late 1970s. The Iranian F-14s have them, and it's quite hard to find a picture of an F-14 without ...
1
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1answer
311 views

What devices measure EPR & RPM on a turbofan engine?

What devices measure EPR & RPM on a turbofan engine?
6
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1answer
752 views

What sensors are required to fly RNAV 5 airways?

In the example shown above: Is an aircraft required to have all 3 sensors listed or just one of them to fly the L512 airway? What ICAO reference confirms the answer? Does 'critical DME' (bottom row) ...
1
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1answer
620 views

Does a Boeing 737 NG have Air Data Modules for the standby Pitot probe and static pressure port?

In other words, how does the ISFD calculate the air data and IR parameters? Or is the ISFD an ADM by itself?
16
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3answers
2k views

Do modern airliners have oxygen sensors in the cabin?

I know that airliners have pressure sensors to check the cabin pressure, and thus check if we can breathe (and get enough O2) inside it so we don't get hypoxia. But that got me thinking: Is there any ...
8
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2answers
2k views

How do tyre pressure sensors in aircraft work?

I am specifically interested in the sensors used on the B777 and B787.
5
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3answers
2k views

What types of fuel quantity sensors are used in an aircraft? How do they work?

Can you explain the different types of fuel quantity sensors used in most recent aircraft? Are ultrasonic tank sensors used these days? How does an ultrasonic sensor work?
14
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1answer
3k views

What are these sensors on the Night Stalkers' Chinook MH-47G?

What are these sensors (or lights) on this heavy assault Chinook MH-47G of the US 160th Special Operations Aviation Regiment, "Night Stalkers"? Source, picture by Russell Hill This regiment was the ...
3
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3answers
2k 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 ...
1
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0answers
235 views

What may cause a pitot tube and Honeywell pressure sensor calibration inconsistency?

It is possible that my issue is specific to my setup, but I thought I'd try here if someone has experienced a similar issue. I will try to explain this clearly as possible, but it may be slightly ...
2
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1answer
421 views

How can avionics detect tailwind? [duplicate]

We can see the effect of the tailwind on the plane's flight direction on the modern military fighter jet huds. I wonder about how can the avionic systems detect tailwind and which sensors using in the ...
5
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4answers
4k views

How are pitch angle and pitch rate measured in an airplane?

What equipment or method is used to obtain measurements of the pitch angle (θ) and pitch rate (q) during flight? Edit: I am asking about how the aircraft systems sense these quantities
5
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2answers
3k views

What is the difference between IMU (Inertial Measurement Unit) and AHRS (Attitude and Heading Reference System)?

According to online sources like wikipedia the difference belies on the addition of an on-board processing system (I assume it means a microcontroller) which outputs already processed data and not ...
21
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2answers
6k views

What is this 'ball' in front of the cockpit of some fighters, e.g., an Su-57?

What is the lump/ball thing visible below and to the left of the canopy in this image of a PAK FA (which became the Sukhoi Su-57), and what is it for? It's also seen on other fighters. Image source