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 ...


30

I assume in your question the autopilot is engaged. When the auto-flight system reaches the limits of its capabilities it simply disconnects. On Boeing aircraft you get a > AUTOPILOT DISC Warning Message on the EICAS and the siren sounds. Now it is all manual flying for the pilots. An example would be turbulence exceeding the auto-flight system ...


22

The "autopilot" is a fairly basic control system. Usually it is composed of just a few components (logically speaking) like a wing-leveler, heading mode, and altitude mode. The autopilot can control the aircraft usually through servo's connected to the control cables or through the hydraulics. External systems can feed into this to do things like follow a ...


15

There are many possible reasons for the autopilot to disconnect. The details will depend on the aircraft, but here are the criteria for a Boeing 737 (source: 737 NG FCOMv2 4.20.2 Automatic Flight - System Description): Autopilot Disengagement The A/P automatically disengages when any of the following occurs: pushing either A/P disengage ...


13

There are two types of autopilots, one for the behaviour around the CoG and one for control of the CoG, as mentioned in this answer. Also sometimes called Inner Loop and Outer Loop. In short: The F-16 is aerodynamically unstable and has a rapid control system that applies control surface deflections to provide artificial stability. This is done to make the ...


13

The Boeing 737 allows a mode called control wheel steering (CWS). The A320 doesn't. For what is CWS, see: Is it possible to disengage only one axis of a two-axis autopilot? The wording on Wikipedia doesn't emphasize this point; however, the final report does. The pilots may also manually control the aircraft in a normal manner with the control wheel and ...


13

You asked about commercial aircraft in general, so I will give an answer from that point of view. Is there any obvious warning when auto-pilot is disengaged? Yes, both visually as flashing lights, and aurally. Furthermore, the lights and tone does not go away until a second confirmation is received from the pilot. For example, pushing the button on the ...


11

Autoland exists at least in part because a pilot can't safely hit (the right part of) the runway (at the right speed and attitude) without visual references, so a lot of precision electronic guidance equipment is needed, and then even more equipment to ensure the first equipment is working correctly. In contrast, the sky is much bigger than the runway. It's ...


9

No, the two systems are completely different. The MCAS of the new Boeing 737 MAX was introduced to help the pilots lower the nose in high angle of attack situations by applying down stabilator trim. This was necessary because the engines are mounted further forwards compared to the previous NG models. Note: We do not know whether or not MCAS caused the ...


8

What about a deer on the runway? What about a BANG coming from the back somewhere? What about a bird strike? What about some indistinct object down the way that looks like it could be an airplane encroaching on the runway? What about a WARNING light coming on? What about a weird vibration starting? What about an engine starting to stall/surge (whoomp ...


8

Other answers already stated that autopilots are essentially very simple things. Especially for someone with an IT background. In some autopilots, there are modes for such events. For example, some G1000/G3000 on light jets are equipped with Emergency Descent Mode (EDM). What does it do? Automatically activates when cabin pressure is lost above a certain ...


7

I've worked on some certified software in a different domain (and slightly less strict); the principle would be similar here. Basically the certifying authority will want to make sure that proper risk analysis was done on the system—both software and hardware—and risks were mitigated to get to certain level of reliability. The authority does not have ...


7

Most transport category aircraft, including B737, have the elevator, the main surface controlling pitch, attached to a horizontal stabilizer that is also movable. The elevator is controlled using the control column (yoke), while the stabilizer is moved using the trim wheels on the central console. This arrangement means the command from the elevator is ...


7

The autopilot is designed to do exactly what it's told, until it can no longer safely do so. At that point the situation is beyond what the autopilot is designed for, so it hands control back to the pilots. Even modern autopilots aren't designed to do much descision-making on their own, let alone a Learjet designed in the 1970's. Adding some sort of ...


7

As @Bianfable points out in the comments RVSM airspace is a problem but ignoring that for a minute: The question of will they continue? depends on the airlines op-specs. Different airlines will handle this differently and it may very well be handled different on different airframes within an airline. A call to base may even occur but there are lots of ...


6

There certainly are few operators who fly to the CAT II ILS minima, one of which is the Cougar Helicopters of Newfoundland, Canada. I know, since I was one of their pilots. Forward visibility for the CAT II is 600 RVR. The CAT III is not used yet due to the certification issues and few other problems, but I assure you that technology used in the Sikorsky S-...


6

All software running on certified equipment will have to follow RTCA DO-178C. This is a fairly complex and expensive process that includes audits specifically with the certification authority (FAA, EASA) throughout the product life cycle, including inspections of requirements, design, implementation, and testing. Any code developed is going to be closely ...


6

There seems to be some ongoing research into just that: There is an effort underway to develop a UAV version of the F-16. This would be based on the QF-16, the remotely controlled target version of the F-16. The air force is already in the process of converting 210 retired F-16s to QF-16s and it was noted that with a little extra work the QF-16 could be ...


6

Since you tagged airbus, I will answer for the A320. The following image from the FCOM shows the FCU (Flight Control Unit) on the glareshield: This is where all inputs for the autopilot are made. The second knob is the HDG OR TRK SELECTOR KNOB, which allows setting a heading. In general these knobs work as follows: To make the autopilot follow the flight ...


6

Generally speaking (not specific to Airbus), what the layman refers to as "autopilot" is actually three logical systems: The Flight Management System (FMS), which figures out where the plane is in relation to the supplied flight plan. The Flight Director (FD), which figures out how to navigate the plane to where the FMS wants it or according to manual ...


5

The following applies to the Boeing 737 NG series, but probably there are no large differences for the MAX series. The FCOMv2 (4.20.2 Automatic Flight - System Description) mentions only the following systems in the Autopilot Engagement Criteria and the Autopilot Disengagement sections: The A/P automatically disengages when any of the following occurs: ...


5

Autoland is an autopilot mode. AUTOLAND could be « armed » while the autopilot is receiving FMS inputs, but once it is « active » it doesn’t use FMS data but the ILS receivers or the ILS and GPS receivers. No need of the FMS neither for the approach, nor for AUTOLAND


5

Moving the flight controls above a certain threshold will disconnect the autopilot. From the A320 FCOM (1.22.30 Auto Flight - Flight Guidance, emphasis mine): AP DISENGAGEMENT AP1 or 2 disengages when: The pilot presses the takeover pushbutton on the sidestick. The pilot presses the corresponding AP pushbutton on the FCU. The pilot ...


5

If your talking about standard rate turns, those are not really practical in large commuter aircraft. As true airspeed increases the maximum turn rate decreases when the bank angle is limited to a comfortable level of less than 30 degrees of bank. So please make this question more specific, which airplane category are you talking about? Usually the ...


4

You don't need the radar altimeter / reverse glide slope system, at all. The energy management required and the trimming are not easy and are in fact unsafe (you need to keep climbing at the best climb rate, in case of say birds). All you need is lateral guidance. Once you are wheels off, you are wheels off, continue the climb via the SID, for example, and ...


4

To my surprise, the FAA clause was added in 2006 after the 2004 notice of proposed rulemaking (NPRM) No. 04-11. Three NTSB recommendations were part of the reason, with the earliest from 1992 (A-92-035). (...) autopilot failures that can result in changes in attitude at rates that may be imperceptible to the flightcrew (...) From the NPRM: This ...


4

The general philosophy is that autopilot is a tool, not an extra pilot, and as such, it disengages when anything goes seriously wrong. Inertial sensor failure? Engine loss? Unusual attitude? Hand control back to the pilots with a nice warning sound. This option isn't taken lightly, especially in high-workload situations like landing, but it's the general ...


4

The cruise autopilot behaves this way by design. From this answer: design parameters for aircraft system safety. For airborne systems, a very thorough analysis is made on failure probability and on failure modes. A safe failure mode is: the system stops functioning completely. An unsafe failure mode: an unintended output, such as a hard-over fail of a ...


4

Bell Textron filed a patent for retractable vortex generators in 2006. The patent is here. Boeing also filed a patent for vortex generators that extend simultaneously with a leading edge slat here.


3

It depends. There are some failures that inhibit both autopilots, and others that may affect only one. Also, policy may be more restrictive -- the QRH may direct not engaging the affected-side autopilot, or it may direct to not engage either autopilot, even though the system wouldn't inhibit it per se. Please note that "instruments" on the Max (and NG) ...


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