IAHFLYR
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Overshooting The Final Approach Course

Mon Jul 30, 2012 1:44 pm

Just found this article about overshoots when turning final to parallel runways.

http://www.flightglobal.com/news/art...-drive-faa-approach-change-374846/

Always amazed me how many overshoots you hear of when clearing aircraft for a visual approach from a base or downwind, and even after they've been told not to overshoot because of aircraft on final to the parallel runway.
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pilotpip
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RE: Overshooting The Final Approach Course

Mon Jul 30, 2012 7:23 pm

Agreed. I think a lot of it has to do with automation and quite frankly, rusting of skills. The two go hand in hand. I can sit there and watch what's going on, the vector I'm getting and based on winds aloft almost always predict when the AP will overshoot. By the time I intervene it's almost always too late and end up a dot off.

At most airports it's not a huge issue, but I'm just waiting for something bad to happen in DEN. Why they put arrivals on the west side of the field while not using the east is beyond me.
DMI
 
KELPkid
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RE: Overshooting The Final Approach Course

Mon Jul 30, 2012 8:17 pm

Quoting IAHFLYR (Thread starter):
Always amazed me how many overshoots you hear of when clearing aircraft for a visual approach from a base or downwind, and even after they've been told not to overshoot because of aircraft on final to the parallel runway.

Try going back to flying the pattern sometime after spending months, or even years, flying nothing but IFR. Yeah, pattern skills get rusty, especially the part about thinking ahead of the plane so that you don't overshoot the base to final turn   Throw in a nice crosswind to muck things up, too... 
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IAHFLYR
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RE: Overshooting The Final Approach Course

Mon Jul 30, 2012 8:40 pm

Quoting KELPkid (Reply 2):
Try going back to flying the pattern sometime after spending months, or even years, flying nothing but IFR. Yeah, pattern skills get rusty, especially the part about thinking ahead of the plane so that you don't overshoot the base to final turn Throw in a nice crosswind to muck things up, too



Not that I don't agree with you, but most of these are very professional pilots using the airports where the 30 degree intercept will be required. Professional pilots with in just about every case in an aircraft with a map showing the runway centerline so I won't completely agree about the IFR part of your statement.

Are the controllers leading them down the wrong path with the vector, in some cases yes. Funny thing is, if the 1,000' of vertical separation was always maintained until established on final as it is during IMC flight conditions this might have not been issue as the overshoots would still have the vertical separation in place.

Education, and more for all involved and that can't be bad.
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CosmicCruiser
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RE: Overshooting The Final Approach Course

Mon Jul 30, 2012 10:34 pm

well if I may add most of the overshoots I've seen are from going too fast and often up to 90deg to the final course. i jet will not capture the loc from 90deg at 220kt without an overshoot.
 
Horstroad
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RE: Overshooting The Final Approach Course

Tue Jul 31, 2012 12:02 am

I´m not into this very deep, but isn´t this an issue with the autopilot? though the pilot is still responsible, this part of flight is often (mostly?) flown by the autopilot. are autopilots too inaccurate? is an improvement of the automatic systems possible/planned/necessary?
 
IAHFLYR
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RE: Overshooting The Final Approach Course

Tue Jul 31, 2012 12:25 am

Quoting CosmicCruiser (Reply 4):
jet will not capture the loc from 90deg at 220kt without an overshoot.



Hell neither will a C152!  
Quoting CosmicCruiser (Reply 4):
most of the overshoots I've seen are from going too fast and often up to 90deg to the final course



I'd say from my seat in a control room that speed is certainly a problem however; a visual clearance off a base or downwind the pilot whether hand flying or turning knobs should not attempt an intercept of any angle greater than 20-30 degrees. If you don't have the room to complete a nice standard rate turn then bail out rather than overshoot. Just my point of view.
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tdscanuck
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RE: Overshooting The Final Approach Course

Tue Jul 31, 2012 1:17 am

Quoting horstroad (Reply 5):

I´m not into this very deep, but isn´t this an issue with the autopilot?

It's not exactly an "issue". It is a property of the autopillot but it's a known property so, if the flight crew aren't managing the automation correctly, that's really not on the autopilot. The problem is that dialing the gain on localizer tracking up high enough to prevent overshoot causes lots of other undesirable properties.

Quoting horstroad (Reply 5):
are autopilots too inaccurate?

Not really. They do what they're told to do. It's a compromise between flight path stability, response time, and not "yank-and-banking" the airplane for no real gain. Having zero overshoot has some implications for the control system that cause other problems.

Quoting horstroad (Reply 5):
is an improvement of the automatic systems possible/planned/necessary?

Yes, yes, and not really. It's a "nice to have." The latest autopilots are predictive and will start the turn early (i.e. before they actually capture the localizer) to help mitigate overshoot. It doesn't eliminate overshoot but it's a lot better.

Tom.
 
rfields5421
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RE: Overshooting The Final Approach Course

Tue Jul 31, 2012 1:40 am

Interesting article.

Much of my small GA flying is at an airport (AFW) with parallel runways 600 feet apart. We get to use the 'far' runway for TNG practice a lot. Also a good hamburger stop.

The other runway can often have a mix of aircraft from turboprops, military jets (T-1, T-38, F-18, AV-8 - are some I've seen on parallel approach) and a few civilian jets including B767 (AA maint base at AFW) and occasionally an FDX DC-10/MD-11, B752 or B727.

Now flying a very small light GA plane, I'm always very careful to locate my big brothers - but I have noticed that some of the AA and FDX pilots do seem to not be in practice with lining up visually. I've never had anything close to a conflict situation.
 
IAHFLYR
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RE: Overshooting The Final Approach Course

Tue Jul 31, 2012 11:23 am

Quoting tdscanuck (Reply 7):
It's not exactly an "issue". It is a property of the autopillot but it's a known property so, if the flight crew aren't managing the automation correctly, that's really not on the autopilot. The problem is that dialing the gain on localizer tracking up high enough to prevent overshoot causes lots of other undesirable properties.



Great explanation, thanks Tom!
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KELPkid
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RE: Overshooting The Final Approach Course

Tue Jul 31, 2012 3:30 pm

Can I make a statement here? having read the article posted by the OP, it's not safety zone incursions that the FAA is concerned about, it is two planes being belly up to each other while on final (due to steep banking) and therefore theflight crews can't see the other bird to maintain visual separation.
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IAHFLYR
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RE: Overshooting The Final Approach Course

Tue Jul 31, 2012 4:29 pm

Quoting KELPkid (Reply 10):
it's not safety zone incursions that the FAA is concerned about, it is two planes being belly up to each other while on final (due to steep banking) and therefore theflight crews can't see the other bird to maintain visual separation.


It's not about maintaining visual separation from the other aircraft using the parallel runway/s.

When the runway centerlines are separated by 4,300' or more, you must use standard separation until the pilot has acknowledged the visual approach clearance, from there on no separation is required as long as the airplanes are not crossing one anothers final approach course. Visual separation is not required with the airplane going to the parallel runway, only with the preceeding aircraft landing on the runway you are assigned. There is also no requirement to share traffic information as long as it is advertised on the ATIS or the controller has advised the pilot approaches are being conducted to parallel runways.

Check out 7110.65U, Paragraph 7-4-4, Approaches to Multiple Runways, for a good read.

The 30 degree intercept IMHO is to avoid the overhsoots it would seem, thus avoiding any hard banking as you refer.
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runner13
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RE: Overshooting The Final Approach Course

Tue Jul 31, 2012 5:50 pm

The problem with this is the approach clearance. You give them the heading to join, then clear them for the approach an that negates the previous heading..

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