aking8488
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Do Airplanes Land "themselves"

Sun Feb 29, 2004 6:22 am

I've been wondering this for some time; I've heard that a/c have the capability to land on auto-pilot and was wondering, is this correct? If so, do pilots generally let the planes land themselves or do they provide input and if so, to what extent? Does the same hold true for take-off? Thanks in advance.
 
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Starlionblue
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 6:30 am

YES!

Since the 60s/70s, this has been a part of airliner capabilities. In fact, in bad weather conditions, most airlines REQUIRE their pilots to use this capability, known as "autoland".

Pilots still mostly prefer to hand fly the big bird to the ground though, for the pleasure of it if nothing else.

I am sure you can find a thousand descriptions of how this works, but in very rough terms it involves two directional radio signals, one vertical (the localizer) and one horizontal (the glideslope). Instruments on the aircraft pick up how far the aircraft is laterally from the localizer and vertically from the glideslope. Based on this the pilots or the autoland system can bring the aircraft down without external visual cues. This is done with the autopilot(s) controlling the flight surfaces and with the autothrottle(s) controlling the engines.

Auto-takeoff is also possible, although used less often. The precision required is less, since you tend to know where the runway is when you are rolling down it.

So why would you not use autoland? Well, some pilots I have spoken to say that the autothrottles tend to do quite a bit of adjusting, and this can be less "gentle" than a pilot, thus causing (marginally) more wear and tear.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
aking8488
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 6:33 am

Thanks a lot Starlion! That was really helpful.
 
AM
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 6:46 am

Actually, there's no such thing as an "auto-takeoff".

The lowest altitude I've heard of at which the autopilot can be engaged when departing is 50ft on Airbus FBW aircraft.
"... for there you have been and there you will long to return."
 
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Starlionblue
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 6:50 am

No problem!

Here's some more stuff for you to read:

FAA description of ILS (Instrument Landing System): http://www.netvista.net/~hpb/ils.html. This is rather technical and boring  Big grin

This page has a great diagram: http://www.flightsimaviation.com/index.php?p=aviationtheory&ch=8.

A good description is here. It shows how the navaids (localizer and glideslope) show up on the instruments, which gives you and idea of how the autopilot "knows" what to do: http://www.scandva.org/ops/proc/ils_approach.htm

You can also find an old copy of Flight Simulator 2000 (the last one with a manual) and check it out. Should be cheap.



"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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Starlionblue
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 6:52 am

I was under the impression that automatic takeoff is possible. I may, of course, be mistaken. Maybe on some planes. Don't see much point in the procedure of course.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
artsyman
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 6:54 am

Actually, there's no such thing as an "auto-takeoff".
***

I do not believe the above to be true. Once the plane is lined up on the runway, it can be programmed to do the entire trip.

J
 
Jeff G
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 7:03 am

There is no such thing as auto-takeoff. That would require the autopilot to be engaged on the ground, and no civilian aircraft I know of will allow that. The FA-18 has an auto guidance mode when it is catapulted off carriers, allowing the pilot to hang on for the ride during the actual shot. Since airliners aren't launched from catapults, obviously this doesn't apply.

Autoland isn't favored for routine operations because touchdowns tend to be rather firm, and besides, pilots would rather handfly landings rather than watch the autopilot do it. In addition, autolandings aren't authorized or even possible on all runways and all airports. They just aren't performed very often.

This topic has come up several times before, BTW. Search the tech ops forum.
 
XFSUgimpLB41X
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 7:28 am

No such thing as auto-takeoff on any civilian airplane...


The CRJ that I fly cannot autoland either- must be disconnected below 80 feet...autolands are not used very often-mostly for certification/currency purposes and in extremely low weather...typically have a bit more bump than manual landings.
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Thrust
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 7:32 am

The Sud Aviation Caravelle was the first jet and I think airplane to do a fully-automatic pilot landing in the early 1960s when United launched it. Or were they not the launch customer?
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SpeedbirdHeavy
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 7:36 am

Once the plane is on the ground though, it is up to the pilot to engage the thrust reversers and actually slow the plane down. The plane doesn't slow itself down on the runway.

I also believe that the autoland system disconnects at 60 kts. Am I right on that point?
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danielbk
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 7:40 am

through most planes do have autobreaks (basically all airlines today if i'm correct) which do slow the plane down (breaking action). the spoilers are also armed (if selected) and deploy once the main gear is on the ground.

Autobreaks usually disconnect at 60kts.

cockpit? it's that little room in the front of the plane where the pilots seat.. but that's not important now
 
Vandelay
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 7:45 am

Autoland capability is limited to crosswinds.
 
socalatc
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 8:01 am

"Autoland capability is limited to crosswinds"..

Where do you get this information?? That is way off. Did you mean to say that auto land is limited in crosswinds??
 
A3204eva
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 8:09 am

There was a program about this on Discovery Wings the other night, they only use it bad weather conditions etc. Pilots generally like to land the plane themselves (its good practice). And most aircraft do have 'auto take off', I use sometimes on my flight sim.

A3204eva
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gordonsmall
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 8:18 am

And most aircraft do have 'auto take off', I use sometimes on my flight sim.

NO civilian aircraft has an auto-takeoff facility that is certified for commercial ops - if it's in flightsim then it's WRONG.

I believe it was actually a HS Trident that made the first fully automatic landing. It was retrofitted and developed by BEA.

As far as I know the first aircraft to be equipped with full autoland "off the shelf" was the Tristar.

I could be wrong, but I'm pretty certain I'm not.

Regards,
Gordon.
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ben
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 8:59 am

Are we confusing this 'auto takeoff' thing with the TOGA button??

I've never heard of a system that will keep you lined up on the runway at takeoff and automatically manipulate the rudder pedals.... scary if true...
 
s.p.a.s.
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 10:48 am

Automatic take-offs...

Maybe not certified, but quite feasible, I think.. Some might remember the nice explanations given by 747Skipper about autolands and automatic roll-out capability some 747s (and also other planes) have, the localizer actually locks the nose gear and the plane keeps runway centreline.

So I guess it would be not impossible to use this for a automatic take-off, not rotation etc, but centreline keeping. Once I was told the MD11 was supposed to have such kind of capability, and some had a special device installed just below the glareshield. Most of the early swissair ones had it.


View Large View Medium
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Photo © Markus Burkhard



Note the opening just above the caution buttons in front of CMD and F/O position, the system was kept but was never used, from what I heard.



Any thoughts?

RS

"ad astra per aspera"
 
fspilot747
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 3:27 pm

Autoland is rarely ever used. Every airline pilot I've spoken to says the same thing. They do it something like a once or twice a year just for systems testing (or something of that nature), not because they choose to. Yes, even in the 'bus.

You'll be surprised how many airline pilots disengage autopilot on descent and handfly.

With regard to auto-takeoffs, why in the world would that even be necessary?


FSP



 
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Starlionblue
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RE: Do Airplanes Land "themselves"

Sun Feb 29, 2004 8:36 pm

Some autolands have "auto-rollout", and some do not.

You also have to remember that if you autoland in zero viz, that's fine. But now what?

How are you going to taxi off the runway? There is no standard system (yet) for getting to the gate, although several are being developed.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
airplay
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 12:15 am

Wow...this has to be a record for the use of "auto" in a thread!

 Smile

Autoland isn't favored for routine operations because touchdowns tend to be rather firm

Landings, regardless what passengers and pilots believe, are SUPPOSED to be "firm". Endlessly floating the aircraft down the runway looking for a gentle connection with mother earth does not make a good technical landing.

So why do pilots take manual control of these really cool huge jets instead of relying on the technically flawless autoland system? Wouldn't you?

 Smile

As mentioned before, there is no auto-takeoff system per se installed in aircraft. But there is a "takeoff" mode in some autothrottle systems.

The one I am most familiar with is the type available for the CRJ. When TAKEOFF is active, the autothrottle system reads the takeoff thrust calculated by the FMS. Once the airplane is lined up and the pilot hits the TOGA button(s) the power levers are automatically adjusted to the takeoff thrust. The pilot must still steer the aircraft down the centerline and rotate when appropriate.

At 80 knots, the autothrottle enters a "hold" submode until rotation when it enters the "CLIMB" mode and adjusts the engine power again using FMS calculated thrust targets.

The CRJ that I fly cannot autoland either- must be disconnected below 80 feet...autolands are not used very often-mostly for certification/currency purposes and in extremely low weather...typically have a bit more bump than manual landings.

The reason the CRJ can't make use of the available autothrottle system to constitute an autoland system is because the autopilot isn't capable of meeting the autoland requirements. So even if certification/currency wasn't an obstacle, the autopilot is.

If you want CAT IIIb capability though, all is not lost. A Heads Up Guidance system is also available that will give you this on a CRJ.

You also have to remember that if you autoland in zero viz, that's fine. But now what?


There has been a great deal of research done on autotaxi systems, but beyond a few airplanes and only one airport with the capability (Schipol I beleive) you won't find it.
 
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Starlionblue
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 12:46 am

The Swedish inventor Håkan Lans devised a system called GP&C (Global positioning & communication). It's used on every ship over 300 tonnes. It may become the standard for aviation. See here if you read Swedish: http://www.uppfinnaren.com/nr2_01/lans.htm. Here is some info on the GP&C hybrid landing system: http://www.gpc.se/landing/index.htm

I once landed in the jumpseat of an SK DC-9 equipped with the system. The pilot showed how he could navigate to the gate in zero viz. The display showed every taxiway, building and so forth. He didn't actually do it since other vehicles were not shown (not equipped with the system). SAS was simply trying the system out. He was just showing off how he could have.

So what is the diff between this and GPS and TCAS? Basically precision. GPS and TCAS become kind of iffy when you are down on the ground since they don't scale down to 5 meters. GP&C allows precisions down to 1-1.5 meters, in other words quite enough to taxi to the gate with really thick fog and no lights.

Also, that kind of system would be installed on ALL vehicles at the airport. Otherwise, how would firemen find a burning jetliner in zero viz for example? Or how would trucks avoid planes in the fog.

Read more about GP&C here: http://www.gpc.se/index.htm

Here is a pertinent article from Flight International: http://www.gpc.se/press/flight5.htm



"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
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Starlionblue
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 1:00 am

A thought occured to me about autoland. The plane only "lands itself" in response to inputs in the FMC/Autopilot and so on. After playing around with the FMC in Dreamfleets FS2002 add-on, I have a sense that it requires about as much attention to detail as landing by hand.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
dl1011
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 2:15 am

Here is some gee whiz stuff about CAT 3 programs, autolands, autobrakes and spoilers and such.

To maintain CAT 3 status, the a/c where I work need to perform an actual or simulated autoland every 30 days. If not, an autoland test is performed by a CAT 3 qualified AMT. We also do line mtc for another outfit that uses 767-300ER's and they also have a 30 day program.

Someone mentioned spoilers/speedbrakes. Spoilers/speedbrakes on the 767 will deploy (if armed) at touchdown. If auto speedbrakes are not armed, when the thrust reverser levers are raised the auto speedbrake handle will be mechanically lifted to the arm position and the speedbrakes will deploy. To stow auto speedbrakes, the handle can be moved to to stow position or if the thrust lever is moved forward, that will also stow the speedbrakes.

Autobrakes on the MD11 can be used to bring the a/c to a complete stop. I think that is also accurate for the 57/67 but not sure.

Rollout guidance (autoland) on the 767 keeps the a/c centered on the runway using rudder and nosewheel steering. Stays engaged until the autopilot is disengaged.

I printed a bunch of material to bring home and of course it is sitting right back in the office. Probably in the recycle bin by now!
 
FoxHunter
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 3:39 am


S.p.a.s.
"Once I was told the MD11 was supposed to have such kind of capability, and some had a special device installed just below the glareshield. Most of the early swissair ones had it."

You were told wrong. No such thing.

 
s.p.a.s.
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 5:07 am

FozHunter

Thanks for the update.. would you by chance know the purpouse of the device I mentioned on my previous post?

Thanks

RS
"ad astra per aspera"
 
XFSUgimpLB41X
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 5:22 am

""The one I am most familiar with is the type available for the CRJ. When TAKEOFF is active, the autothrottle system reads the takeoff thrust calculated by the FMS. Once the airplane is lined up and the pilot hits the TOGA button(s) the power levers are automatically adjusted to the takeoff thrust. The pilot must still steer the aircraft down the centerline and rotate when appropriate.

At 80 knots, the autothrottle enters a "hold" submode until rotation when it enters the "CLIMB" mode and adjusts the engine power again using FMS calculated thrust targets.""""


Airplay- who's CRJ is this that you talk of.... everyone I know doesn't even have autothrust- including ours.





Quite possibly one of the worst, most uninformed threads I have read on this forum in a while.
Chicks dig winglets.
 
airplay
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 5:56 am

Quite possibly one of the worst, most uninformed threads I have read on this forum in a while.


Perhaps before you berate people you should become informed yourself XFSUgim....whatever.

Just because you never heard of something, doesn't mean it doesn't exist. The CRJ autothrottle is available as an after-market modification under FAA and TCCA STC.

And...if you're interested, the flightcrew of the 2 CRJs that have it installed to date are very satisfied.

[Edited 2004-02-29 21:57:54]
 
FoxHunter
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 5:58 am

"FozHunter

Thanks for the update.. would you by chance know the purpouse of the device I mentioned on my previous post?

Thanks

RS"

I'm not sure what "device" you're referring to.

If you look at the GCP right in the middle you will see where it says "Auto Flight", pressing this turns on the autopilot if above 100 feet on the radio altimeter, press it again would switch to the other autopilot. When aligned with the runway I also press this to arm the auto throttles. When I push up the throttles for take off the auto throttles engage and advance the engine power to the computed take off thrust.
 
XFSUgimpLB41X
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RE: Do Airplanes Land "themselves"

Mon Mar 01, 2004 6:47 am

Hey now.. I wasn't referring to you. I was mentioning on a side note that I had never heard of a canuck jet having autothrust. The uninformed referrence was all the other side chatter of autotakeoff and such.
Chicks dig winglets.

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