usscvr From United States of America, joined Jan 2010, 70 posts, RR: 0 Posted (2 years 4 weeks 1 day ago) and read 3253 times:
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?
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...
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.
"I have always imagined that Paradise will be a kind of library."
thenoflyzone From Canada, joined Jan 2001, 2791 posts, RR: 11
Reply 3, posted (2 years 4 weeks 21 hours ago) and read 2848 times:
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.
us Air Traffic Controllers have a good record, we haven't left one up there yet !!
cornutt From United States of America, joined Jan 2013, 338 posts, RR: 0
Reply 4, posted (2 years 4 weeks 4 hours ago) and read 2644 times:
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.
IAHFLYR From United States of America, joined Jun 2005, 4790 posts, RR: 22
Reply 9, posted (2 years 3 weeks 4 days 4 hours ago) and read 2169 times:
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:
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.
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