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The most recent additions to this article adds information but is desperately in need of editing. I'm not expert on this subject someone who's more knowledgable to edit it. Comatose51 02:34, 21 January 2006 (UTC)

Software Science or Control Engineering[edit]

It is not very informative to say that modern autopilots use software to control the aircraft, without specifying exactly what the software does, we might as well claim they work by magic.

It is more accurate to say that modern autopilots are implemented as computer software. As far as concepts are concerned this is mere implementation detail. The methods of autopilot design remains the body of knowledge called control engineering, which makes no assumptions concerning the implementation; the design may be implemented conceptually as analogue circuits, shift registers, computer code or even electro-mechanically. Gordon Vigurs 19:58, 29 May 2006 (UTC)

Scope of Article[edit]

The material has moved on from autopilots, which are basically systems to maintain straight and level flight, to inertial navigation, which serves to navigate specified classes of flightpath by generating autopilot commands. It would appear logical therefore to include ILS, TACAN, LORAN and Doppler navigation as well, but this would wander too far off the point.

In missile parlance, the autopilot serves to remove all the variability in airframe response due to altitude and Mach number, maintains stability with shifting centre of gravity position, and ensures a unity steady state gain. The input to the autopilot is typically a lateral acceleration command which is generated from the guidance (if derived from radiation emitted or reflected from the target) or navigation (if steered to a point in space).

In short, the autopilot is responsible for controlling the handling modes of the aircraft (short period pitch oscillation, and Dutch roll), but control of the trajectory is the responsibility of the navigation.

Pitch Oscillations: There is a difference between dampers and Autopilots. Since you mention "pitch oscillation" it needs to be stated that the system that corrects this is a "damper" or Stability Augmentation system, not an Autopilot which provides pilot relief. Even the sensors (rate gyros, etc) are different and provide not steady-state outputs, but rate signals that are only present when there is movement or acceleration. For example: Pitch stab aug was so critical on the F-4 that the Autopilot could not be engaged unless that channel was functional; no pitch aug no autopilot, and no heading hold, altitude hold, etc. Some pilots would even abort if the pitch aug did not work. Some aircraft like the T-38 only had dampers. The original A-10 not only had no autopilot (just dampers), but no inertial nav system either. MSgtUSAFret (talk) 22:15, 16 August 2008 (UTC)

The sentence beginning 'modern autopilots use software' appears to rename the autopilot 'flight control system' and calls the navigation system the autopilot.

The various categories of 'autopilot' presented are different flight path controllers, all of which potentially employ the same innermost loops (e.g. autopilot proper), and are limited in scope to aviation.

As mentioned above, trajectory control of a missile is governed by a navigation law, typically proportional navigation or some form of line of sight (command to line of sight or beam rider). Furthermore, the autopilot does not necessarily control normal acceleration and bank angle: in skid to turn missiles, they control pitch and yaw lateral acceleration, in some cases they control angle of attack. In a space booster, it is the orientation in space which is controlled in order to steer the vehicle along a pre-defined optimal attitude program. In a satellite, or spacecraft, the autopilot serves primarily to control the orientation in space.

In all cases the 'autopilot' refers to the innermost set of loops, whose purpose is to render the vehicle response reasonably constant in the presence of disturbances and variations in the flight regime (typically altitude and Mach Number) and vehicle mass distribution.

The article would be more compact and accessible if autopilot, guidance and navigation were treated separately.Gordon Vigurs 07:27, 30 May 2006 (UTC)

Further, the Computer system details clearly identify one specific architecture. The detailed implementations in hardware/software can be very different. Surely the way many automatic flight control system contractors go about implementing their system is as varied as the number of aircraft and other flying bodies that are currently or formerly in operation. Handment 21:46, 20 March 2007 (UTC)

It was mentioned that the autopilot can control every phase of flight except for taxi. If a reference is available, please insert it. As far as I know, to date, autopilots cannot control the aircraft down the center line of a runway. In some cases the AP may be available on the ground but in this case the pilot's manual will indicate that the AP can be engaged once the a/c has reached a defined altitude or a period of time after Weight On Wheels = false. In some cases the AP control laws do not allow engagement but the AP may be ARMED on the ground and will engage at a defined altitude or a period of time after Weight On Wheels = false. The reason for this is safety. Therefore, the AP can control ascent, level flight (cruise), descent, approach and landing. The Takeoff phase, as far as the control laws are concerned, ends when the AP is engaged. [BE]

It is mentioned that the AP is a part of the FMS in the write-up. The AP is separate code from the FMS (or FMGS). [BE]

As far as the trajectory, navigation and autopilot go, there is in most flight control systems a function called the Flight Director, or FD. The FD can take inputs from the guidance panel pilot settings to the (ie heading, altitude, speed, climb-modes, etc) or the FMS (or FMGS). The Flight Management System or Flight Management Guidance System (also separate from AP and FD) has numerous "jobs", one is to work with the radios to manage navigation by ground stations (eg VORs) and/or GPS. Most modern aircraft, commercial or military, are considered highly integrated as each of these systems is critically dependant on the other but as Gordon Vigurs mentions, they should be treated separately. Short story longer, the control laws for AP, FD, and the FMS are separate as should be the descriptions. Mention of the other system can be made as a point of reference only. [BE] —Preceding unsigned comment added by (talk) 15:59, 16 June 2008 (UTC)


An anonymous user from the address (talk · contribs) recently added the following note to the CAT IIIc entry in the Aviation Autopilot Categories of Landing section:

(Please look for Globalhawk, which might be the 1st to have such capabilty as of 2006)

"Globalhawk" presumably refers to the RQ-4 Global Hawk UAV. I have reverted the addition, as it was unreferenced and not written in an encyclopedic tone, but if someone with more knowledge about the subject than me could dig up a reference, the mention should presumably be included in some form. —Ilmari Karonen (talk) 01:03, 7 September 2006 (UTC)

Aviation Autopilot Categories of Landing[edit]

The descriptions of categories CAT III a/b/c don't match those in the Instrument Landing System-Article. I assume that they are both describing the same thing? 21:39, 3 October 2006 (UTC)

"It is usually a triple-channel system or dual-dual system." As far as I can see, the article doesn't explain what this means. Can someone provide a reference or an explanation? (talk) 15:11, 13 August 2008 (UTC)

Should this section be in the autopilot article? It really belongs in ILS. --Drpixie (talk) 02:50, 16 June 2014 (UTC)


This article doesn't credit any sources. It looked like a good building block for me to go from on a university essay I'm writing, but the lack of sources means I can't chase up what's said and verify for myself, and quite frankly referencing wikipedia for a piece of coursework isn't a great idea... —Preceding unsigned comment added by (talk) 14:09, 15 November 2007 (UTC)

Autopilots and TCAS[edit]

I know of no situation where an autopilot will take action in a TCAS RA situation, and have removed this line from the article. The first step is invariably to disconnect the autopilot and flight directors if fitted. —Preceding unsigned comment added by (talk) 00:10, 27 August 2008 (UTC)

Self-locating INS?[edit]

The statement "IRU's are completely self-contained and use gravity and earth rotation to determine their initial position (earth rate)." doesn't ring true to me. I'm happy that IRUs can self-align (to find North and Up) without external inputs, but believe that they all need an external Initial Position - either in the form of a manual IP insert, or from some alternative navaid like GPS. I'm inclined to trim this suspect detail out rather than to expand (since it's a long way off-topic), but thought I'd better give others a chance to comment first since my detailed interest in IN design ended almost twenty years ago. Zeusfaber (talk) 21:50, 20 February 2009 (UTC)

Autopilots capable of landing a plane[edit]

When did the first autopilot capable of successfully landing a plane come into use? (talk) 20:28, 15 April 2009 (UTC)

See Autoland. Rwessel (talk) 01:56, 31 October 2009 (UTC)

Autopilot invention date (1912/1911)[edit]

After reverting the edit by, it appears that there were several different dates involved. The original work on *aircraft* autopilots appears to have been done by Sperry in 1912, and publically demonstrated in 1914. 1911 was the year in which the US Navy accepted a *marine* gyroscopic gyrocompass/autopilot (, and development of that dates several years further back (patents seem to date back to at least 1908 - #1,242,065, for example). Rwessel (talk) 04:09, 16 November 2010 (UTC)

Gyrocompass bases on a quite different physical phenomenon than gyroscope, as explained in the article. I doubt if gyrocompass could be used for a marine autopilot, as (in its early forms) it reacted very slowly. The gyro_scope_ was used for marine (even submarine) autopilot much earlier than 1911, if I remember correctly around 1890s? --Kubanczyk (talk) 00:00, 9 January 2013 (UTC)

Modern Autopilot Image[edit]

I have a WP:COI with Honeywell Aerospace, who has donated several images under a Creative Commons license. I added an image of a modern autopilot system they contributed. Since the image is not clearly distinguishable as a Honeywell product and I did not mention them in the caption, I didn't feel this was a COI edit and went a head and put it in. Corporate Minion 22:08, 5 September 2012 (UTC)

Source of the term "George"[edit]

The cite states one possible etymology for "George" was George Debeeson.... "one of the key contributors to its development.[1]" This seems dubious.

That same cite article contains a section written by George Debeeson's son, Max. In that article, the son writes, "Whether George's invention was incorporated into the popular mechanism of the day or not is uncertain."

Prior to World War II, I can find no references to the term "George" as an autopilot. After the war, the term is quite common. It is highly doubtful pilots of that era would be aware of an individual who's son isn't certain of his father's contribution to a device invented and commercialized by the well known Elmer and Lawrence Sperry of Sperry Corporation. Why not, "Let Sperry Do It?"

According to a number of World War II pilots, the term was coined by the RAF. There are three theories: 1) "Let George Do It," referred to the aircraft's owner, King George VI (reigned 1936:1952); 2. The device is essentially a gyroscope. During World War II, the military phonetic for G (Gyro) was George (it is now Golf)<^ "The International Phonetic Alphabet for Radio Communications". Communications Specialists. Retrieved 2009-02-27. ></ref>; 3) A popular phrase from the first half of the twentieth century and the 1940 George Formby film, To Hell with Hitler ("Let George Do It" was the original title). The phrase means when something has to be done, let somebody else do it. From 1934 to 1945, George Formby was the top comedian in British cinema and in 1939, was the number one film star of all genres.<^ "FORMBY IS POPULAR ACTOR.". The Mercury (Hobart, Tas. : 1860 - 1954) (Hobart, Tas.: National Library of Australia): p. 5. 25 February 1939. Retrieved 24 April 2012.></ref>

I would propose that at minimum, these alternative explanations be included.Jjlaughlin (talk) 07:43, 22 November 2012 (UTC)

Fixed. I've simply removed the dubious statement, as it is clear it is incorrectly sourced. It has minimal relevancy but introduces a great risk of misinforming the readers. --Kubanczyk (talk) 23:52, 8 January 2013 (UTC)

Removed picture of B737-800 autopilot, picture is clearly a screenshot from a flight simulator program.[edit]

I have removed from this article the alleged picture ( of the autopilot from a B737-800 as the picture was clearly a screenshot from a flight simulator program that was then cropped. As an encyclopedic article, I believe this did not constitute an accurate real-life representation of a real B737-800's autopilot interface.

As an aside, I am unfamiliar with nominating images for deletion. As the picture in question is not in use anywhere else (as of writing) and is clearly not a photograph of an actual B737-800's autopilot, perhaps it would be prudent to nominate this image for deletion? King Arthur6687 (talk) 02:33, 29 September 2014 (UTC)

Do current autopilots ‘automatically’ cause a steep or vertical dive when thrust is lost?[edit]

Is this how autopilots currently function?: Maintain programmed attitude and course through all entered waypoints. Ignore all fuel exhaustion or loss of thrust events. 'Automatically' stall the aircraft in response to a loss of thrust event. Disconnect when the full stall occurs to allow a subsequent steep or vertical dive to the surface.

In other words, is this typical of a summarized pseudo command set which is executed after a crew becomes incapacitated?:

Maintain programmed attitude and course through all entered waypoints.
Ignore (or don’t monitor) fuel supply.
Ignore (or don’t monitor) thrust.
Negative altitude deviation detected:
Pitch up until programmed altitude recovered.
Further negative altitude deviation detected:
Increase pitch up until programmed altitude recovered.
Full stall detected:
Completely disconnect autopilot. Do not reconnect.

Fuel exhaustion loss of thrust result: Full stall, then steep or vertical dive. Terminal dive, midair breakup, or (if very lucky) intact stall / dive oscillation until surface impact. Almost certain loss of all life. Massive damage or pulverization of all material, severely complicating accident investigation. (Evidently in the case of the Payne Stewart tragedy loss of thrust resulted in a near vertical dive at almost mach 1, and thus extremely extensive destruction on impact.)

Here’s a highly summarized rational pseudo command set:

Maintain programmed attitude and course through all entered waypoints.
Monitor fuel supply.
Monitor thrust.
Loss of thrust detected:
Terminate altitude maintenance routine.
Execute best glide distance maintenance routine.
Loss of thrust verified (fuel exhaustion amplifies confidence of loss of thrust):
Execute search for best emergency landing or ditching location (ELDL) within safety margined glide distance (detail 1 below).
Load course for best ELDL (includes location to begin landing maneuvers data).
Terminate all previous guidance routines.
Execute guidance to ELDL routine.
Reduce glide speed to minimum necessary to maintain full stability and reach ELDL with safety margin.
Load specific ELDL approach and landing or ditching routine.
Monitor landing maneuvers location waypoint flag.
Landing maneuvers location flag detected:
Execute ELDL approach and landing or ditching routine (includes flap, landing gear, and flaring routines specific to each ELDL).
Activate ELT.

Result: Possible survivors - possibly full survival. Possibly minimal or no injuries. Maximally intact material for accident investigation.

What is the actual current state of affairs? Did autopilots ever operate as I described in the first example? The Payne Stewart tragedy seems to suggest so. The MH370 tragedy might suggest so as well, though from my vantage point the matter’s less clear. If so, do autopilots still operate in such a profoundly flawed manner?

One would assume not - presumably the Payne Stewart tragedy alone prompted correction of autopilots so that they respond to loss of thrust by at least reliably executing a transition to maintenance of the minimum safe glide speed if no guidance function is available, or best glide distance if full functionality as I described above is available.

This is not a significant technical hurdle - the minimal addition of loss of thrust detection followed by transition to an optimum glide routine is almost trivial. The full routine I described above requires more design effort but is not difficult, nor would implementation add any mass nor anything more than very minor cost to any autopilot equipped aircraft.

But I can find no discussions of the matter. Hopefully my searches simply failed. But If I understand this situation correctly and no discussion or corrective action has been taken autopilots will continue to react to crew incapacitation and fuel exhaustion events by ultimately placing the aircraft into a steep or vertical dive to the ground or water. And crew incapacitation and fuel exhaustion events will recur - they’re inevitable in the course of time. And such an impact might occur in a populated area.

Can this possibly be the current state of affairs? Surely the aviation community isn’t maintaining such a massive blind spot. Anyone with information please advise.

Detail 1: A very substantial number of such locations should reside in the autopilot’s data storage system - it should contain a very robust global map of graded emergency landing or ditching locations. This is not a technology challenge - modern data storage is very robust. --H Bruce Campbell (talk) 05:56, 3 November 2016 (UTC)

The aviation community is not maintaining a massive blind spot of the kind you have described. Basically, you are proposing a high-technology, high-expense solution to an extremely rare accident scenario. There are many, many failure mechanisms within the design of any vehicle that occur so rarely that no attempt is made to guard against them. Total incapacitation of flight crew is an example. In the Payne-Stewart case, the crash was not caused primarily by the autopilot because the autopilot had disconnected. The crash was caused primarily by incapacitation of both pilots, a very rare event indeed. Dolphin (t) 21:01, 3 November 2016 (UTC)
H Bruce Campbell has asked a similar question in another place. My reply is here. Dolphin (t) 00:21, 4 November 2016 (UTC)

I very strongly disagree with Dolphin51 in almost all respects. I’m not proposing a high technology nor high expense solution. And this problem is not so rare nor so insignificant that inaction can be justified - not by a considerable margin, particularly if a factor in the MH370 tragedy as might very well be the case. (In that section of the article: "If no control inputs were made following flameout and the disengagement of autopilot, the aircraft would likely have entered a spiral dive." In this scenario when thrust was lost the autopilot attempted to maintain altitude anyway until it fully stalled the aircraft, then it disconnected, leading directly to a spiral dive, an abjectly stupid and manifestly destructive response to a loss of thrust event. Forgive me please for being blunt and dramatic, but this is a massively destructive and wholly indefensible glaring design flaw.)
For my base proposal, refinement of ordinary autopilots to include thrust monitoring and a simple transition to a controlled glide when loss of thrust is detected is, in my personal electrical and software engineering experience, literally an almost trivial engineering task. A reasonably experienced engineer could complete the basic design and coding modifications in one day, then revise a stock autopilot to render it ready for testing within another day. (Someone with direct autopilot design experience could probably complete both tasks within one day.) Thorough testing through certification would take longer of course, but only because the certification process for all design revisions is fundamentally labor intensive and cumbersome. But very little extra system cost would result - only a very modest increase to amortize the design, testing, and certification labor, with the certification labor by far the largest component in my estimation. (Depending upon preexisting access to thrust or fuel data, or the possibility of sufficiently inferring loss of thrust in software, no extra manufacturing cost would be involved since no significant hardware design changes are involved.)
The full system I propose is certainly more complex and would require much more design, testing, and certification time. But only readily available off the shelf technology is required. And similar technology in the form of auto-landing systems already exists and presumably has proven capable in practice. Even the full system I propose is a relatively moderate design and development task.
Let’s keep this in perspective. The costs involved in my base proposal would be absolutely trivial compared to the costs involved in the MH370 incident. Had the 777 simply cruised at minimum glide speed to impact with the surface lives might have been saved and the search, with all of its massive expenses, wholly unnecessary. My full system proposal might have saved even more - if the MH370 crew was incapacitated rather than on a conscious mission of destruction, a full system would have landed the aircraft at the highest level ILS within the 777’s very substantial range, possibly saving all lives, and very likely preventing the loss of the hull, and certainly eliminating all the search costs. I haven’t tried to rough in the accounting, but I suspect the MH370 losses alone eclipse the cost of development and implementation of my proposed full system. And another big bonus: In either case the accident investigation would have been swift, solidly conclusive, and, especially with my full system proposal, dirt cheap.
I do not propose a science fiction level solution, but rather an off the shelf technology level solution - ordinary current technology is more than sufficiently capable of accomplishing either of my proposals. And I do not propose a system which overrides crew authority - the system refinements I propose may be overridden by the crew at will at any time as an ordinary control panel task. These refinements are not directed to terror or suicide events - they address crew incapacitation related tragedies.
And I reiterate that this appears to be a massive blind spot. Given the evident number of crew incapacitation related incidents in recent years and the sheer magnitude of the worst of them, this is a critical design oversight which must be corrected. And such tragedies will recur - recent experience suggest so clearly. And while autopilot caused steep or vertical dives to the surface in response to crew incapacitation and subsequent fuel exhaustion have only involved unpopulated surface areas thus far, that won’t remain true forever.
Do we really need yet another tragedy to prompt action to address this issue? I encourage experienced avionics engineers and accident investigators to join this discussion. I suspect we could develop a consensus rather rapidly, especially for my base proposal. --H Bruce Campbell (talk) 03:57, 4 November 2016 (UTC)
Talk pages are not forums for discussing the topic itself, but for discussing improvements to the articles. Your comments are beyond the scope here. - BilCat (talk) 06:42, 4 November 2016 (UTC)
Ah, my blind spot! Thank you - I stand corrected regarding Wikipedia mechanics and etiquette. Should I remove my material from this page, and related material from other Wikipedia article talk pages? And having just read more guidelines but still being inexperienced, I get the impression that Wikipedia's just not a proper forum for this issue - I see no provisions for a discussion of this nature (understandably). Thus I suspect I should find an independent host for this issue (true?). I want to do the right thing... --H Bruce Campbell (talk) 07:49, 4 November 2016 (UTC)
It probably doesn't need to be removed at this point, as long as no one else comments on the proposal. Yes, you're correct that Wikipedia has no provision for discussions of this nature, and it's by design, in line with Wikipedia's purposes as an encyclopedia. Thanks for understanding, and being open to learning about how Wikipedia works. So many new uses aren't willing to learn, and assume Wikipedia is just like Facebook or the like. I hope you can stay around and be contributor. Editing Wikipedia can be a rewarding experience if one takes the time to learn the ropes. - BilCat (talk) 07:58, 4 November 2016 (UTC)
Thanks bunches and will do! Wikipedia is a gleaming global treasure and any tiny part I can suitably play is an honor. I eagerly welcome civilized personal guidance, and stand happy to remove my material here whenever deemed suitable. I just registered two domain names to provide a home for this issue (AutoPilot.Tech and, but it will take time to erect a site for my rants and an open discussion. Thanks very much! --H Bruce Campbell (talk) 08:58, 4 November 2016 (UTC)