usscvr
Topic Author
Posts: 61
Joined: Sat Jan 30, 2010 2:03 pm

Reducing Separation - How Safe Is It?

Thu Jan 31, 2013 7:25 pm

The Memphis Commercial Appeal newspaper is reporting that "...federal regulators have tweaked a key aviation standard to improve the flow of cargo jets in and out of FedEx's world hub at Memphis International Airport."

The report continues by saying that the new standards have been in place at Memphis since last Nov. 1, and will be expanded to other airports with concentrations of heavy, wide-body aircraft, including San Francisco, Louisville and Atlanta, over the next couple years.

The report says that minimum spacing between departing aircraft was reduced to 2.5-3 miles, from 4 miles for most planes. It also mentioned that spacing was increased for some smaller planes for wake turbulence separation standards. Arriving aircraft were not addressed.

My question is: How much (to what degree) does this reduce safety?



http://www.commercialappeal.com/news...-in-memphis-save-jet-fuel-cut-and/
A:319/320/321/332/333||B:717/721/722/735/737/738/739/742/744/753/762/763/772/773/787||DC8/9/MD80/GF14/C5/C130/C141
 
chuchoteur
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Joined: Tue Sep 12, 2006 9:17 pm

RE: Reducing Separation - How Safe Is It?

Thu Jan 31, 2013 8:09 pm

Quoting usscvr (Thread starter):
My question is: How much (to what degree) does this reduce safety?

It doesn't.

I believe that they are using the new air traffic situational awareness system that FedEx have installed on their fleet (I think most, if not all?). This means that aircraft are able to maintain "visual" separations in conditions that would not otherwise permit it, thus maintaining optimum traffic flows.

This type of technology and procedure is not only part of the FAA NextGen program, but also the european SESAR Joint Undertaking. They are also using it for aircraft deconfliction outside of radar coverage on the north atlantic track system. In Trail Procedures enable aircraft to step climb and reach optimum altitudes when aircraft are in relative close proximity to each other at different flight levels. Another evolution os the ability to communicate with ATC and get clearances via data communications/satcom, it is more robust than HF...
 
texan
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RE: Reducing Separation - How Safe Is It?

Thu Jan 31, 2013 8:30 pm

Quoting usscvr (Thread starter):
My question is: How much (to what degree) does this reduce safety?
Quoting chuchoteur (Reply 2):
It doesn't.

  

The FAA wouldn't allow reduced separations if it increased the risk to safety. The advance in technology have allowed for separation to be reduced in many cases--ICAO provides a manual detailing how and when separation can and should be reduced with different technologies.

Texan
"I have always imagined that Paradise will be a kind of library."
 
Thenoflyzone
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RE: Reducing Separation - How Safe Is It?

Thu Jan 31, 2013 11:02 pm

This is the first i hear of reduced separation for departing traffic. Especially one involving wake turbulence.

Reduced separation on final approach is not uncommon. Most busy airports have them, which enables them to go down to 2.5 nm separation, once you meet all the requirements, which include minimum runway occupancy time. (under 50 seconds, i believe). however when wake turb is involved, you have to maintain adequate separation.

Up here in Canada, i believe only YYZ has approval for 2.5 nm sep on final. Not sure about YVR. I know YUL is laying down the groundwork to get approval, but it is proving to be more difficult, as the runway occupancy time is way too high, around 69-70 seconds.

Thenoflyzone
us Air Traffic Controllers have a good record, we haven't left one up there yet !!
 
cornutt
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RE: Reducing Separation - How Safe Is It?

Fri Feb 01, 2013 3:51 pm

Quoting thenoflyzone (Reply 4):
This is the first i hear of reduced separation for departing traffic. Especially one involving wake turbulence.

I'm guessing Fedex works on sequencing their departures to keep heavies together, so there are fewer holds needed for wake clearance. BTW, I''ve experienced wake on an MD-80 -- it was, erm, interesting.
 
CosmicCruiser
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Joined: Tue Feb 22, 2005 3:01 am

RE: Reducing Separation - How Safe Is It?

Sat Feb 02, 2013 1:52 pm

Quoting cornutt (Reply 5):
Fedex works on sequencing their departures to keep heavies together,

not that I'm aware of.

Quoting chuchoteur (Reply 2):
This means that aircraft are able to maintain "visual" separations in conditions that would not otherwise permit it, thus maintaining optimum traffic flows.

what would that be? I just retired in Dec and don't think I'm aware of something like that. They did implement a bunch of RNAV SIDS & STARS a year or so ago.
 
RussianJet
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RE: Reducing Separation - How Safe Is It?

Sun Feb 03, 2013 6:15 pm

Quoting cornutt (Reply 4):
BTW, I''ve experienced wake on an MD-80 -- it was, erm, interesting.

Could you elaborate? I've always been intrigued to know what that must feel like if you run into it heavily.
✈ Every strike of the hammer is a blow against the enemy. ✈
 
CosmicCruiser
Posts: 2049
Joined: Tue Feb 22, 2005 3:01 am

RE: Reducing Separation - How Safe Is It?

Sun Feb 03, 2013 8:36 pm

I just a little article from my previous employer that got into the "RECAT" thoroughly and as far as the pilot goes, it's invisible.
 
rfields5421
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Joined: Thu Jul 19, 2007 12:45 am

RE: Reducing Separation - How Safe Is It?

Mon Feb 04, 2013 1:35 am

Quoting RussianJet (Reply 6):
Could you elaborate? I've always been intrigued to know what that must feel like if you run into it heavily.

I was on a TWA 727 landing at DFW behind a heavy and got hit by turbulence crossing the threshold. The aircraft was bounced up about 50 feet and tipped 40 degrees left wing down.

Nice go around followed over the top of Terminal E.
 
IAHFLYR
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RE: Reducing Separation - How Safe Is It?

Mon Feb 04, 2013 3:57 pm

Any way to mitigate wake turbulence separation would be helpful and will certainly be done safely. There are projects underway and in place using GLS approach procedures where the vertical path angle can be reprogrammed to provide different touchdown locations on the runway thus helping reduce wake turbulence separation requirements.

Check out the GLS approach information around Page 14:

http://events.aviationweek.com/html/...ng%20RNP%20Flight%20Operations.pdf

There is also work being done with NASA regarding the reduction of wake turbulence for departures under certain wind/runway configurations. Page 10 starts some information about this concept:

http://ntrs.nasa.gov/archive/nasa/ca...asa.gov/20080048309_2008049032.pdf

Quoting cornutt (Reply 4):
BTW, I''ve experienced wake on an MD-80 -- it was, erm, interesting.



The wake from a B738/9 quite often brings a "what are we following" from the flight crew even while the Boeing's are still clean with speeds up around 280 KIAS. I've encountered the wake from a BE30 turning a high short final in front us one day not long ago which got our attention very quickly, and we were in a BE20! It's everywhere.
Any views shared are strictly my own and do not a represent those of any former employer.

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