Podcast #128: We chat with Kent C Dodds about why he loves React and discuss what life was like in the dark days before Git. Listen now.
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Just because aviation developers use Python, does not mean that Python actually goes flying. Lots of aviation development is about testing, stressing, validating, analyzing, and documenting the code that does go flying. Python is an excellent language for all that validation work, even though it stays on the ground.


67

As far as Airbus is concerned: Each unit is composed of two dissimilar boards, one driving the output and the other checking it. Dissimilar means both different CPUs and chipsets (A320 uses i386 (Intel) and m68k (Motorola); newer models use different combinations, basically whatever was widely used at the time they were designed) and software written by two ...


64

Most commercial aircraft transmit their GPS-based position twice per second. This is part of their Automatic Dependent Surveillance – Broadcast (ADS–B) broadcasts. The problem with providing world-wide receiver coverage for this system is that the frequency it uses only travels line via line of sight, so it won't travel past the horizon. Providing coverage ...


48

There is a general design principle, that some, but not all, of the behavior of the flight guidance system or autopilot should be visible to the pilot. Usually automatic engagement or disengagement of a control system is indicated, but sub-modes of these controls or manual changes might be unindicated. That sounds simple and logical, but in reality it's a ...


45

My short answer: Stability is reduced by shifting the center of gravity aft. Shifting it past the neutral point makes the airplane unstable, so movements away from the trimmed state are accelerated. This increases maneuverability. Flight computers are multiple redundant, if one dies the others take over. Slow unstable airplanes can be flown by a human pilot,...


40

None of the avionics systems I've worked on have used Linux or any consumer-type operating system. There are a few main issues. First is the practical. Most safety-critical avionics involve a control loop and thus have a real-time requirement. That means it's not just important to run a process and get an answer, you need to get the answer within a ...


39

There are no language recommendations or requirements, other than what is sensible given the verification requirements in the various standards (e.g., DO-178B/C). For the highest design assurance levels, the generated code must be inspected down at the op-code level to ensure no known processor gotchas are invoked. You also end up having to test every part ...


38

The small bulb houses the antenna that provides the satellite communications for the internet link. Inside the aircraft several wireless access points provide a WIFI signal to the passenger's equipment. The wireless access points are connected to a central modem which in turn is connected to the transceiver unit. The transceiver uses the rooftop antenna to ...


37

Redundancy is not only achieved by multiplying the computers, but also by diversifying them. On Airbus airliners, two different computers are used (one with Intel chips, the other with Motorola chips in case of the A320) and software is written twice, one for control, the other for monitoring, by two teams which are not allowed to interact. To cite from ...


37

It's a serious crime, but what that guy did, only affecting one system out of three, would be unlikely to cause a crash if the pilots were half way reasonably competent. The take-off would be rejected as soon as the blocked side's speed tape failed to "come alive", well below 80kt (the pilot not flying checks that both speed tapes start to move as the ...


34

As a software engineer who works at a defence company that develops and sells mission critical (but not safety critical) systems, I can confirm that there's a pretty even split between development in Ada (95) for our legacy products and various flavours of C/C++ for our new products. Development in both is of course done to the appropriate standards. Python ...


33

According to BBC's description, he blocked one of the pitot tubes. (...) a piece of foam was found glued inside a navigation system part which stopped it from functioning. It was reportedly inside the tube leading from the outside of the plane to its air data module, a system that reports aircraft speed, pitch [sic] and other critical flight data. A ...


31

Short two-bullet answer (1) Differences between VOR/DME and TACAN include: TACAN uses UHF (VOR uses VHF) to increase bearing determination accuracy; a single frequency for range and bearing (VOR/DME uses two frequencies); two small rotating drums with parasitic antenna elements (VOR uses a large circular array of antennas). A VOR/DME station actually uses ...


29

Failure modes to consider: Overheating. This changes the chip's timing properties and eventually results in error. This can manifest as single-bit errors in the middle of seemingly normal operation; it will eventually crash, but may output bad data first. Water damage. Manifests as a parasitic resistance on the board and may cause you to misinterpret bits ...


29

The short answer is that no safety-critical avionics systems that I'm aware of use Linux, and the highest criticality systems often don't use a commercial operating system at all. However, Linux is used in other safety-critical applicaitons like the Space X Falcon 9 and medical applications. A more detailed explanation is difficult to do without going into ...


29

The beam strength decreases as you move away from it's own centreline, so is it actually that the entire modulated signal strength decreases which when de-modulated is effectively a difference in amplitude modulation depth? Your question is very relevant, it can arise naturally if you happen to look at web pages using half correct descriptions (for ...


28

To answer your first question, ADS-B stands for Automatic Dependent Surveillance - Broadcast. Automatic in the sense that it operates without external stimulus (unlike radar) Dependent in the sense that the surveillance information is derived from on board systems Surveillance in the sense that it's primary intended to provide surveillance information to ...


27

As other answer pointed out: A CPU can fail. Either partially (giving erroneous answers), or totally. Moreover all computer are subject to cosmic radiations that can once in a while flip a bit in memory (in addition to other sources of error like short circuit, ...). That's why scientific experiments and long running servers use ECC memory. Spaceships also ...


27

You're right. It's the ECM/EW antenna/equipment (fairing) in all the aircrafts except Typhoon. This photo shows the details of EW/ECM suite in Gripen. Source: www.w54.biz In Typhoon, it is the engine bleed air heat exchanger. The part is in detail here. Source: b-domke.de


26

There is no switch for the FDR, but there is a circuit breaker and by pulling this you are removing aircraft power from the FDR. However, this does not mean you are necessarily turning it off, as some FDR can be equipped with an internal power supply as a backup to aircraft power. The quote in the question (bolded emphasis mine): You also cannot turn ...


26

A Hobbs meter measures the time spent in a general aviation aircraft with the power on. Planes differ in that time is easier to record than distance. For a given airspeed, the distance covered by the aircraft depends on the wind, altitude, and other factors. Modern airliners would record the period each engine has run, flight time, cycles (one cycle is one ...


25

The screens are LCDs, which have a polarized filter layer over them. That layer is usually placed at a 45° so they are misaligned with your polarized sunglasses which are aligned vertically. You can confirm this is the problem by turning your sunglasses at different angles and see if the screen changes.


25

Yes there will be a delay, but the delay caused by the control loop is really tiny. I've seen position control loops run successfully and stable at a couple of hundred Hz for simulator motion systems, and the time delay is just one iteration frame = less than 10 msec. And as @ymb1 correctly points out, if we deflect any control surface the end position is ...


24

It's a holdover from the old days when microphone technology wasn't as advanced. The military adopted "dynamic microphones" as the standard, which were less noisy than the alternative "carbon microphones." Carbon microphones required a DC bias voltage to operate, and the dynamic ones did not. Fast forward to current airplane microphones, which are ...


23

From what I have studied at my instrumentation course, it rotates and reads the angle between the current position and the reference position. You then have several (3-4) of them around the fuselage because a roll maneuver (for example) will alter the measurements asymmetrically and in this way you can compensate for this effect.


22

The device you are talking about is called a transponder. This is a device that listens for a signal (an interrogation) and responds with information about the airplane including an ATC assigned code, altitude information and additional aircraft info for certain equipment. There are 2 ways ATC watches airplanes: Primary Radar Secondary Surveillance Radar ...


22

Searching the NTSB Accident Database which also covers some international commercial flights for the key words "hack", "hacked" do not provide any results related to hacked avionics. Likewise using the keyword "tampered" does not provide any results related to deliberate tampering with avionics (mostly "tampered" wreckage). There is one individual, Chris ...


22

The short answer is that it's what the market wanted. There is always a lot of discussions between the airlines and manufacturer's before Airbus or Boeing commits to building a new aircraft. In this case both Boeing and Airbus came to the same decision -- the airlines were being driven by one single factor to replace their A320 or B737 fleets, they just ...


20

An AOA vane (like what you have shown) works by aligning itself with the local airflow, like an arrow. The angle to some reference line (normally aircraft fuselage horizontal) is then measured with a potentiometer/RVDT/etc. This is the local angle of attack. Often the local angle of attack is converted to aircraft angle of attack through a calibration ...


20

There's seldom a reason for manufacturers to design and build their own black boxes. It's expensive to run a production line to design, build a test a few. It's just cheaper to get an agreement with a company to make them for you. The second photo below shows a popular recurring model from Honeywell, which appears to have been used on the A330, B737 and B777....


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