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PPVRA
Topic Author
Posts: 8605
Joined: Fri Nov 12, 2004 7:48 am

What Does It Take To Implement Steep Approach?

Fri Jul 23, 2010 6:36 pm

There are so many stories of noise complaints at urban airports, I am wondering why don't more airports implement steep approaches. At least smaller ones like MDW, CGH, and possibly in the future Briscoe Airfield just north of Atlanta. I'm sure there are many other ones as well.

Is this frowned upon? Too complex/expensive for most airports?

[Edited 2010-07-23 11:39:29]
 
mmedford
Posts: 449
Joined: Mon Nov 05, 2007 5:54 pm

RE: What Does It Take To Implement Steep Approach?

Fri Jul 23, 2010 6:42 pm

Well I can help on the ILS side of it...

First you need to have the engineering staff come out; for the facility mod to change the glide angle...this is easily changed on a glideslope by lowering the antennas to the correct portion (based on the type of glideslope).

While this is going on; flightcheck needs to make an appearance which consists of flying several approaching to define the new glide angle and clearance paths. This can take multiple passes due to antenna heights, and the techs adjusting the magic of the equipment. Once all said and done...new proceedures are published.
 
IAHFLYR
Posts: 4397
Joined: Sat Jun 25, 2005 12:56 am

RE: What Does It Take To Implement Steep Approach?

Fri Jul 23, 2010 10:38 pm

IIRC, the FAA has put a limit on a vertical angle greater than 3.2 degrees, anything higher requires a waiver and probably a barn full of special training procedures etc.
 
BMI727
Posts: 11300
Joined: Mon Feb 02, 2009 9:29 pm

RE: What Does It Take To Implement Steep Approach?

Fri Jul 23, 2010 10:45 pm

The main trick from the airplane side of the equation is to be able to descend at the steeper angle while holding speed and having the engines sufficiently spooled up to facilitate a go around.
 
FredT
Posts: 2166
Joined: Thu Feb 07, 2002 9:51 pm

RE: What Does It Take To Implement Steep Approach?

Sat Jul 24, 2010 6:46 am

Moving the antennas means a full recomissioning of the GP. A day of flying, not just a few approaches.
 
IAHFLYR
Posts: 4397
Joined: Sat Jun 25, 2005 12:56 am

RE: What Does It Take To Implement Steep Approach?

Sat Jul 24, 2010 12:50 pm

Quoting FredT (Reply 4):
Moving the antennas means a full recomissioning of the GP. A day of flying, not just a few approaches

Not quite and entire day of flying, but around 2 hours of flying 10 degrees either side of the localizer at the GP intercept altitude back and forth across the localizer, then holding patterns at the final approach fix, then some recorded low approaches over the runway at 50'.
 
DiamondFlyer
Posts: 3547
Joined: Wed Oct 29, 2008 11:50 pm

RE: What Does It Take To Implement Steep Approach?

Sat Jul 24, 2010 3:06 pm

I doubt that landings are nearly as large of a cause of noise complaints compared to takeoffs. I've spent some time living no more than 3/4 of a mile right off the departure end of a small to midsized airport, and can say landings aren't bad. Takeoffs are the big noise makers.

I don't think a steeper glideslope really helps with noise much. All it does it change the operating environment, and to some extent (if special training is required), close the airport to a large number of airplanes.

-DiamondFlyer
 
mmedford
Posts: 449
Joined: Mon Nov 05, 2007 5:54 pm

RE: What Does It Take To Implement Steep Approach?

Sat Jul 24, 2010 5:41 pm

IAH is pretty much dead on with the timing...

when we do a flightcheck like that, usually someone is up on the tower ready to move the antennas as needed to maintain the required height ratios.

Depending on the techs present; it can be done in 10 runs and commissioned...or if it gets really bad; flightcheck will have to land, and pick up a load of fuel.

Also its' usually done during the day because of the crucial clearance run; which provides your fly up response on the flightdeck.
 
aviopic
Posts: 2423
Joined: Sat Mar 13, 2004 7:52 pm

RE: What Does It Take To Implement Steep Approach?

Sat Jul 24, 2010 7:57 pm

Quoting DiamondFlyer (Reply 6):
I doubt that landings are nearly as large of a cause of noise complaints compared to takeoffs.

  
A NAP T/O would have a lot more effect to reduce noise pollution.
 
dispatchguy
Posts: 639
Joined: Sun Jan 29, 2006 6:08 am

RE: What Does It Take To Implement Steep Approach?

Sat Jul 24, 2010 9:31 pm

Quoting IAHFLYR (Reply 2):
anything higher requires a waiver and probably a barn full of special training procedures etc.

For example, at BIAR/AEY (Akureyri, Iceland), they have an ILS with a 5 deg GS, and on the approach plate it has a warning that it is not to be flown by aircraft that are not specifically certified to fly such an approach, and the crew trained, to fly a 5 deg glideslope.
 
Western727
Posts: 2031
Joined: Wed Jan 03, 2007 12:38 pm

RE: What Does It Take To Implement Steep Approach?

Sun Jul 25, 2010 2:12 pm

Quoting DiamondFlyer (Reply 6):
I doubt that landings are nearly as large of a cause of noise complaints compared to takeoffs.

SNA comes to mind. Their NAP T/O is quite well-known (and add some cool "drama" to the T/O); they don't use a steep landing approach, do they?

Still--why do they do steep landing approaches at LCY for example? London is flat, after all. Noise abatement?
 
dispatchguy
Posts: 639
Joined: Sun Jan 29, 2006 6:08 am

RE: What Does It Take To Implement Steep Approach?

Sun Jul 25, 2010 3:02 pm

Quoting western727 (Reply 10):
Still--why do they do steep landing approaches at LCY for example? London is flat, after all. Noise abatement?

I'm thinking obstacle avoidance...
 
PPVRA
Topic Author
Posts: 8605
Joined: Fri Nov 12, 2004 7:48 am

RE: What Does It Take To Implement Steep Approach?

Sun Jul 25, 2010 6:34 pm

Thanks all for your answers, especially the more technical side.

Quoting DiamondFlyer (Reply 6):

That's true, though it could be that extra little thing to help out a bit. Then again, like you said, it's one more restriction for the airport and they probably don't want that.
 
Viscount724
Posts: 19316
Joined: Thu Oct 12, 2006 7:32 pm

RE: What Does It Take To Implement Steep Approach?

Sun Jul 25, 2010 9:10 pm

Quoting western727 (Reply 10):
why do they do steep landing approaches at LCY for example? London is flat, after all. Noise abatement?

There are quite a few obstacles near LCY.


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