Autoland functionality

[brent p h]

In 737 NG type is this feature very reliable? I have noticed quite a few comments on these forums regarding it. How many of you actually use it?

[Velocipede]

I do. It is reliable about 95% of the time. However, do you want to bet your life on the 5% on a Cat III day?

That's why I prefer the HGS over the autoland system, but that's just me.

[brent p h]

Originally Posted by Velocipede

I do. It is reliable about 95% of the time. However, do you want to bet your life on the 5% on a Cat III day?

That's why I prefer the HGS over the autoland system, but that's just me.

Understood... However what does that 5% entail? Does the flight system omit the flare or does it start "fishtailing"? I suppose a Xwind component might make things kind of hairy. I don't have any heavy jet time yet (other than flight sim) but I was just curious about the phenonenon.

[ILSstud]

Not sure how much technical jargon you want to delve into regarding this subject, but this semester in my attitude and control systems class we had to do a project regarding autopilot performance.http://www.soe.ucsc.edu/~elkaim/Docu...navigation.pdf I used that site as a primary reference. Very interesting stuff dealing with convergence and divergence of flight paths. That "5%" that you are refering to can refer to any number of configurations with the autopilot. Either the system can choose to not flare the aircraft leading to a hard or even destructive landing or in some cases the autopilot can go from a stable second order system like this to an unstable system in which fishtailing and "unstable searching" can occur in the flight path. This would necessitate an immediate go-around, abandoning the approach and trying again if full scale deflection occured. Also in terms of vertical guidance the aircraft can exhibit the same behavior in terms of unstable pitch oscillations which could potentially lead into a stall as the aircraft is already operating in the back side of the power curve. Anyways, interesting reading in that link I gave you even though it mostly deals with GPS signals being used to verify position.

[Velocipede]

High flares, off centerline, early power reductions, something interrupting the ILS signal. There are various problems. All require a go around. There are some of the same problems with the HGS, but since you are flying the airplane by hand, you have the innate ability to detect these issues better than if you're merely observing the aircraft's performance.

But, understand, this is all just personal preference.

[B767Driver]

Originally Posted by brent p h

In 737 NG type is this feature very reliable? I have noticed quite a few comments on these forums regarding it. How many of you actually use it?

Autolands are like fielding a routine ground ball. Most of the time they bounce right into your glove...but occasionally they bounce before your glove requiring quick corrective action on your part.

The last one I did the autopilot kicked off at 50'. I was still able to knock the ball down and make the throw over to first. The key is to follow the ball all the way into your glove and not assume anything will be routine.

Automation is great...but sometimes it makes me a bit skiddish...especially using it close to the ground. If I'm flying...I know exactly what imputs I'm going to make to the controls next. If the electrons are flying...I don't have the same confidence. But it is nice to sit back and monitor the approach while the automation takes some of the workload off of the situation.

[Cheechako]

It sure is great to have after the 6 hour all-nighter from Hawaii when Seattle is at Cat III mins.

[Velocipede]

Welcome to my nightmare. Try the all-nighter ANC turn to PDX in Cat III.

[Doug Taylor]

Worst I've had in recent memory was weather at minimums in JFK, landing on 22R with a massive crosswind.

No autoland available and the three aircraft in front of you just went on the missed.

And there you are thinking to yourself, "Welp, I've had about three landings in the last 60 days, this ought to be interesting."

[Cheechako]

Yep, that's the way it was, and we liked it!!

[frog_flyer]

Originally Posted by B767Driver

Autolands are like fielding a routine ground ball. Most of the time they bounce right into your glove...but occasionally they bounce before your glove requiring quick corrective action on your part.

Best aviation simile I've seen yet.

[brent p h]

Originally Posted by Doug Taylor

Worst I've had in recent memory was weather at minimums in JFK, landing on 22R with a massive crosswind.

No autoland available and the three aircraft in front of you just went on the missed.

And there you are thinking to yourself, "Welp, I've had about three landings in the last 60 days, this ought to be interesting."

Wow!!! No autoland available!!!! B767? Weather at minimums???!!! This would make my underwear hate me even in the sim!!!!! LoL

[taseal]

Originally Posted by Doug Taylor

Worst I've had in recent memory was weather at minimums in JFK, landing on 22R with a massive crosswind.

No autoland available and the three aircraft in front of you just went on the missed.

And there you are thinking to yourself, "Welp, I've had about three landings in the last 60 days, this ought to be interesting."

that is just hilarious

[taseal]

well.... this was an automated landing

[Polar742]

Originally Posted by taseal

well.... this was an automated landing

...or a test pilot trying to make the airplane do something it didn't want too...

[Stone Cold]

Originally Posted by Polar742

...or a test pilot trying to make the airplane do something it didn't want too...

Actually, it was a dumb pilot doing dumb pilot tricks with a new airplane, passengers on board, and a fly-by at an airshow. It didn't work well.