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50 votes
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Do aircraft have accelerometers?

Most modern aircraft, which includes long range airliners since around 1970, all airliners since not much later, and basically anything with glass cockpit, do have very accurate accelerometers for all ...
Jan Hudec's user avatar
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28 votes
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Why do electronics have to be off before engine startup/shut down on a Cessna 172?

You shut the components off to protect the sensitive electronics from electrical surges that may occur during start up of the engine. Circuit breakers are designed to trip open if too much current in ...
Dean F.'s user avatar
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26 votes
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What does Line imply in Line Replaceable Unit?

"Line" refers to "Air Line" or "Flight Line". It's the same "line" as when you refer to "line operations" or, for pilots, "line indoctrination&...
John K's user avatar
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23 votes

Why do electronics have to be off before engine startup/shut down on a Cessna 172?

The main problem lies in the behavior of the coils inside the starter. As all inductors, they build up a magnetic field - this stored energy will cause a high spike in voltage while disconnecting. ...
tsg's user avatar
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16 votes
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How stable is the "customer" power on a commercial aircraft?

There is a pretty great article on the design of the 777 electrical system here. Power for avionics needs to be clean to ensure there are no spikes or dips that would cause avionic failures as ...
Dave's user avatar
  • 101k
15 votes

In case of failure in the Electronic Flight Instrument System, how would they be transferred between each other?

On the Embraer 170/190-series, the normal display layout is as follows: There is an automatic display reversion logic when one or more panels fail. The following image shows this logic: There is ...
Porcupine911's user avatar
  • 3,123
14 votes

Are there any standards on the dimensions of PFD symbols?

Yes there are standards. There are industry standards which not regulatory standards, but they have been deemed acceptable by the regulatory agencies (e.g. FAA). So following them is usually accepted ...
Gerry's user avatar
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13 votes

How stable is the "customer" power on a commercial aircraft?

AC to AC conversion with frequency change from 400 Hz to 50/60 Hz is obtained by transforming AC to DC first (usually to 28 VDC to be compatible with batteries) and then using a static power inverter ...
mins's user avatar
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13 votes
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Do military jets' radar jammers block their own radar? And, if not, why not?

If you are emitting RF, you can be seen. There are two ways to emit RF: 1. Transmit (or leak) a RF signal, and 2. Reflect a RF signal. A jamming device emits (usually) high amounts of RF, with the ...
mongo's user avatar
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10 votes

Can large airliners such as a 747 maneuver without electricity?

Flight controls are pretty hard to break For the 747 (at least through the -400) specifically, the controls are entirely hydromechanical, so yes, they will work without electrical power. In general, ...
UnrecognizedFallingObject's user avatar
9 votes

Could a terrorist hack the ILS?

There are numerous unclassified papers talking about LOC, GS, MLS and other navaid jamming. There are also instances of that happening, both intentionally and unintentionally. The issue with consumer ...
mongo's user avatar
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8 votes
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What is the encoding difference between ARINC 429 BNR and BCD formats?

Your basic decoding strategy looks correct -I didn't double-check the values, but the logic is sound. Note, however, that the difference of BCD vs two's-complement is not the only difference between ...
multipleinterfaces's user avatar
7 votes

Do aircraft have accelerometers?

I think you need to define "modern" aircraft, the question is pretty broad as-is. And even interpretation of what you mean could vary. i.e. are you referring to a real time dial showing actual Gs in ...
Michael Hall's user avatar
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7 votes

How does the control-board on small drones govern their flight?

Maneuverability with this kind of drone comes with their small size and high thrust-to-weight ratio. When you scale such a dynamic system, the time scales with the square root of size, so the smaller ...
Peter Kämpf's user avatar
7 votes

Can both AC ground and DC ground connect to the same Ground STUD

I am assuming you are referring to whether or not it is acceptable to connect the ground side of an AC supply and a DC supply to a common ground stud on the airframe. According to the FAA's Aircraft ...
Saxon Xander's user avatar
7 votes

What does Line imply in Line Replaceable Unit?

It refers to the flight line, in other words the ramp where aircraft are parked. The component is relatively easy to remove and replace. Other parts require special tooling, jigs, cranes, and so. So a ...
Jim's user avatar
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7 votes
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How is the memory system configured in avionics computers?

I haven’t designed an avionics computer myself but have worked on many real-time systems. Essentially the key is to work out the worst-case timings and make sure that the system remains within spec ...
Frog's user avatar
  • 1,852
6 votes
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What is the standard power supply and voltage supply on modern airliners?

Typically 115 VAC, 400 Hz for most large aircraft, which can be rectified and stepped down for DC powered subsystems. Smaller GA airplanes typically use 12, 14 or 28 VDC for their electrical systems.
Romeo_4808N's user avatar
  • 74.1k
5 votes

Aviation Embedded Systems

There are various standards out there and ways of doing things but DO-178C is the latest iteration of the document that outlines how real time avionics are to be programed. Certifying agencies like ...
Dave's user avatar
  • 101k
5 votes

Do military jets' radar jammers block their own radar? And, if not, why not?

That's not the nature of how ECM works. Here's a primer on basic electromagnetic countermeasures as was used during the Vietnam War. Since ECM, or radar jamming, ...
Romeo_4808N's user avatar
  • 74.1k
4 votes

What measures can the aerospace industry take to deal with changes in the electronic industry that are incompatible with its own conservatism?

The aviation industry is strongly cognisant of these risks. At least one research programme has attempted to analyse them in depth, the Aerospace Vehicle Systems Institute (AVSI) Consortium Project #...
Daniele Procida's user avatar
4 votes

Could a terrorist hack the ILS?

Yes, An ILS could be jammed or disrupted. It is a narrow directional signal emitting from an antenna at the runway. A pilot uses other means of navigation to intercept its signal and verify the ...
STWilson's user avatar
  • 1,746
4 votes
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What is the data size of Hilton Software's WingX Pro 7 app and all of its databases?

The app itself only takes up about 15-20MB, according to the Google Play or iTunes app store, where as ForeFlight takes up 226MB (almost a quarter of a gigabyte) and Avare is less than 2MB and free. ...
Zach W.'s user avatar
  • 606
4 votes
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Can I carry a waveform generator with me inside an airplane?

You did not specify a country for your domestic flight, but in general: Assuming you do not intend to power it on and use it during the flight, it should not be a problem. Esoteric and unusual ...
abelenky's user avatar
  • 30.7k
4 votes

Are piezoelectric energy harvesters too expensive to be used commercially as a power source in drones or small aircraft?

What are the disadvantages of such a system being used as an auxiliary power source if not the main one? Is it not worth the money? It's not worth the weight. The power that can be extracted from ...
Therac's user avatar
  • 27.6k
4 votes

Do aircraft have accelerometers?

When I worked in the industry in the early 2000s, Eurofighters had g-sensors recording during flight, and put you into a different engine service regime above a certain limit. There was a matching ...
Pete Kirkham's user avatar
4 votes

How can I know the manufacturer of the PFD (Primary Flight Display) of the current mainstream passenger aircraft?

The 737 does NOT use a G1000... Many of these devices are made by companies like honeywell or the makers of the airframe themselves although they may very well source the physical screen from another ...
Dave's user avatar
  • 101k
4 votes

Has a passenger's consumer electronic device ever actually caused a crash?

There has not been an actual crash to my knowledge, but I personally have had passenger cell phones interfere with my comm radios several. Once to the point where we couldn't hear anything but the ...
Khantahr's user avatar
  • 3,106
4 votes

How do Luneberg lenses hide a stealth aircraft's real signature?

Since the attached reflector and the rest of the aircraft are at the same position and velocity, they form a single target. There will be no second blip. They're one and the same. When a target has ...
Therac's user avatar
  • 27.6k

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