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-   -   Fun times at OSH arrival (https://vansairforce.net/community/showthread.php?t=162509)

dweyant 07-31-2018 06:37 AM

Quote:

Originally Posted by fl-mike (Post 1276443)
The 36 departure controller Friday morning was awesome.
Efficient and enthusiastic. Even complimented the Dc-3 for blowing him off the stand during runup!
Somebody in line knew him by name, so I?m guessing he is a regular.
Admittedly a more controlled process, but he was also having fun.

You must have been in line Friday morning when I was. I always enjoy taxiing out down 36. It's like driving your plane through an aviation museum. And "having" to hold for a couple minutes for a group of five P-51's to take off, right in front of me sure didn't suck :).

-Dan

airguy 07-31-2018 08:25 AM

Quote:

Originally Posted by Kyle Boatright (Post 1277158)
Scott's math is substantially right. With a 90 knot arrival, and 1/2 mile spacing, that puts 3 planes a minute over Fisk - 180 aircraft an hour. That nets 1 plane/minute/runway if there are three runways in use, no gaps, no go-arounds, and no departures. Even with a 10 hour "window", you're limited to a max of 1,800 landings/day. If you want to use a 13 hour window (7AM - 8PM), you only get 2340 landings a day.

No amount of holding or extending the arrival chain is going to fix that bottleneck.

That said, EAA has to spend the available runway time well. Identify the things which unnecessarily eat into the arrival slots. Military fly-by's on Saturday/Sunday? Sorry, no can do. Mass arrivals? Love 'em. Have the first airplane on short final at 7:05 AM.

I have a piece of video from Sunday afternoon 2016 that I just looked at, which I shot from the threshold of 18R. I see 5 airplanes crossing the numbers in 45 seconds and a sixth going around for spacing. Granted, that may be the top end of what is doable and safe - cut that back to 4 airplanes per minute per runway - that's still a LOT better than the numbers being discussed here of 1 airplane per runway per minute. This is not a "pie-in-the-sky" scenario here - I watched it happen and recorded it. It ran that way all day Sunday in 2016.

az_gila 07-31-2018 08:27 AM

Quote:

Originally Posted by jclark (Post 1277156)
A well-executed mass arrival (tight formation) can be safer and is A LOT more efficient so even with a little "setup time" you can have more throughput.

The key is "well executed".

Maybe.. but for the sake of these hypothetical caclulations - what time was lost in the paractical cases that have occured of the last few years.

History is a better indication here than a statement of "lot more efficient".

Practical wins out over theoretical. What is the actual history of "well executed"? :)

Paul 5r4 07-31-2018 09:38 AM

My initial impressions were a little of the blame blanket falls on us the pilots. Pilots do have to accept some of the responsibility, example... big thunderstorm dead ahead, AKA super saturated Ripon/Fisk traffic and choosing to proceed. I've watched a few of the youtube videos of the arrivals from the cockpit and have been forced reexamine my thoughts. Several points here. The notam and the spacing in that notam which has been the standard for years was half mile spacing. They changed it as they have the right to do and we as pilots must try to comply as safely possible. On flight radar 24 I saw everyone out at the lakes, Ripon, Fisk and the many others inbound as I was sitting along approach end of 36 so you know ATC had it on theirs! A hazardous situation was unfolding before there eyes and they kept turning airplanes back. Others have done number crunching of airplanes per minute per runway and I feel I agree with those results. I did some math to see how many airplanes could safely be inbound to Fisk. Using the required half mile spacing, (and my numbers account only for the low... 1800/90kts approach)... 10 miles from Ripon to Fisk accounts for 20 aircraft. It's appears to be roughly a flight distance of about 16 miles around green lake so there could be about 32 aircraft holding there. Rush lake is about 10 flying miles around which would be another 20 aircraft. That's 72 aircraft not counting those already passed Fisk towards the airport or those flying the high approach. It seems that 99.9% of the time this would work fine. This was the .1% when it didn't. Looking at FR24 there appeared to be 2 or 3 times as many aircraft out there.
Understandably those pilots were stressed to the max, frustrated and aggravated at having been turned back out many times. If I had been inbound still 50 miles out and witnessed the cluster on my ADSB, I would have landed elsewhere until things cleared a bit. No other way to look at it, voluntarily flying on into that chaos is simply a risky choice.

I don't know what the answers are but I know what they are NOT. Any type of reservations system wouldn't work. Don't ask me why, I just don't like the sound of it! To me this is like saying "We as pilots can't figure this out so big brother you regulate it for us."

A second Ripon out there someplace for super busy times has some merit. Separate aircraft by high wing/low wing... Experimental vs certified... even or odd number tail numbers. It would have cut the congestion at Ripon and the lakes in roughly half. Of course, this only solves half the problem. Still have to get everyone sequenced in for landing on the same three runways.

Mass arrivals..... hmmm..... I like Dan Hortons thoughts.... not during expected peak arrival times. I especially like his suggestion of making any mass arrivals "part of the show." Any mass arrivals starting Monday morning as soon as the field opens. An hour or two of this might get most of them in. And hey..... We'd all love landing with a thousand people looking on admiring our supreme airmanship skills. May God help the poor guys ego that might not get it right and half the world watching, (folks on the line and of course you tube). ;-)

Somewhere in this thread there's mention of military planes doing flybys before their landings. We all saw TopGun.... Negative Ghostrider, the patten is full. When they grant a flyby ATC should first check the scope and see whats going on at Ripon/Fisk and only then any request granted accordingly.

ATC's increased spacing created some of the problems here. When you are in trail and looking at the guy in front of you at a comfortable distance that's about 1/2 maybe 3/4 of a mile. Seems to work pretty good. Any more and the guy ahead becomes pretty hard to see.
Last, if inbound and monitoring Fisk approach and looking at a mess on ADSB, as many did hold a ways out, or land elsewhere until it's safe.

MIKE JG 07-31-2018 09:52 AM

Given the choice between a reservation system or what we witnessed on that Sunday...... I'll take a VFR reservation system any day if I plan to fly in.

Given the numbers EAA put out last night, 10,000+ airplanes arrived at some point during the week and over 600,000 attendees, the show size is getting into another category. If there was a shortage of volunteers and workers in 2018, including apparently ATC folks, it's not going to get any better next year.

thinkn9a 07-31-2018 10:11 AM

Thrashing,.... is the term
 
Quote:

Originally Posted by jclark (Post 1277155)

The "system" has its limits.

Decades ago, I recall that when certain computers got beyond say 80% capacity then page swapping took up more time than processing and once you crossed a certain threshold, throughput went DOWN dramatically. There is a point in certain systems that you want to stay below.

We cannot speed up the processor (# landings the RUNWAYS can handle) but we can add more "memory" (waypoints and holding stations) ... IN MY OPINION

What James was recalling is called ?thrashing?,..... the official technical term. I really like it. I talks to what happens when you approach the limit of throughput. Instead of graceful degradation, the performance drops dramatically as you approach the limit. (Time is spent getting ready instead of actually producing output)

As an aside,... driving home from Osh,.. I actually experienced ?zipper? merge instead of everyone try to merge at last moment,.... it was darn near a thrill. We actually moved through the choke point MUCH more quickly than we would have if folks tried to crash merge at the last moment. ( unfortunately the zipper merge only happened a once,.many other slowdowns occurred) Maybe something to learn there.

rv7charlie 07-31-2018 10:17 AM

When I was still attending (admittedly, a decade ago), the controllers were fighting to get a chance to work OSH. It was a badge honor, driving competition and waiting lists like some of you experience trying to get a hangar on a public airport. Unless things have radially changed, the only reason for a controller shortage is failure to allocate.

bruceh 07-31-2018 10:21 AM

Probably a sacrilegious thought here, but maybe take a page from AOPA and split the big show into smaller regional events spread through out the year? It just can't keep getting bigger and bigger without having more of these safety issues with arrivals. I know this will probably never happen....

fl-mike 07-31-2018 10:40 AM

This takes me back to undergraduate engineering:
https://en.wikipedia.org/wiki/Queueing_theory

Way, way back!

I think CB..err...Mr. Clark may have some academic resources at his disposal! :D

Senior project(s)?

rv7charlie 07-31-2018 10:45 AM

Quote:

Originally Posted by bruceh (Post 1277241)
Probably a sacrilegious thought here, but maybe take a page from AOPA and split the big show into smaller regional events spread through out the year? It just can't keep getting bigger and bigger without having more of these safety issues with arrivals. I know this will probably never happen....

It happened for me over a decade ago. :-)


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