Mid-air collisions too rare to worry about!
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mid airs...how about mid grounds?
~~~~~~~~~~~~~~~
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FAA investigating after planes collide on runway
CHARLOTTE - The FAA is investigating a collision between two U.S. Airways planes
on the ground at Charlotte-Douglas International Airport.
A spokesperson says the wing of one aircraft clipped the rudder of another while
both planes were on the taxiway at about 5:20 p.m. Saturday.
Flight 704 was preparing to take off for Germany and Flight 413 was en route to
San Francisco. Both planes were airbuses.
The FAA says both aircraft were taken out of commission after the collision.
The 200-plus passengers on the German-bound plane were given food vouchers and lodging.
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FAA investigating after planes collide on runway
CHARLOTTE - The FAA is investigating a collision between two U.S. Airways planes
on the ground at Charlotte-Douglas International Airport.
A spokesperson says the wing of one aircraft clipped the rudder of another while
both planes were on the taxiway at about 5:20 p.m. Saturday.
Flight 704 was preparing to take off for Germany and Flight 413 was en route to
San Francisco. Both planes were airbuses.
The FAA says both aircraft were taken out of commission after the collision.
The 200-plus passengers on the German-bound plane were given food vouchers and lodging.
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A few more calculations
Assuming the aircraft were distributed in only half the available airspace or 15 million cubic miles it would mean each aircraft has approximately 3,000 cubic miles or a space 20 miles long, 20 miles wide and 7 miles high.
Let's suppose that aircraft distributed absolutely randomly in the U.S. airspace (laterally and vertically) are separated by an average of 40 statute miles. This is already highly unlikely for reasons I'll mention in a moment, but bear with me.
Let's assume that each aircraft occupies a cube of about 1000 feet on a side.
With six thousand flights in the air, it turns out that the chances of two aircraft occupying the same 1000-foot cube of air at any given instant are about one in 1600, according to my back-of-envelope calculations.
Now, with 6000 aircraft aloft, and one in 1600 being in danger of a midair … well, the "Big Sky" hypothesis just doesn't look that safe any more.
Yes, the average separation might be 40 miles, but there is no guarantee that every pair of aircraft will have exactly 40 miles of separation. And in fact there's a pretty good chance that aircraft will be meeting in the same small points of the airspace fairly often with 6000 airplanes flying around.
So the Big Sky hypothesis fails.
Imagine an ocean in which explosive mines are anchored in a perfectly regular array, with an average of 500 feet between them. Since they are stationary in this array, 500 feet sounds safe, and it is. But now suppose that the mines are untethered and that currents in the ocean move them in completely random directions, all at the same time. Within a very short time, some of the mines will collide and explode. The 500-foot separation is great as long as it's guaranteed, but when the mines can move freely, they need a much, much greater average separation in order to remain safe, otherwise the chances of two of them reaching the same point at the same time are far too great.
You can imagine the same thing with billiard balls on a pool table. Same principle. If they are all motionless with two feet between them, no problem. But if you start them all moving randomly, a few of them will begin to collide almost immediately.
Of course, the Big Sky hypothesis is already unrealistic. It assumes that there are no airports, and that every aircraft occupies a totally, completely random chunk of sky. But in real life, airplanes take off and land from airports, which greatly concentrates their density at certain points, and they fly along airways, which also concentrates them, and they follow published arrival and departure procedures, which concentrates them still further.
Still, ironically, you may be better off by restricting aircraft to specific airways and routes and maintaining separation between them actively and explicitly then you would be by letting them wander randomly and uncontrolled and hoping that the laws of probability will prevent mid-air collisions. The chances of a mid-air can be kept as low as desired by an appropriate level of precaution and vigilance in explicit separation, but the chances of a mid-air when aircraft wander about at random are fixed by the laws of probability and cannot be reduced. So the risks are actually lower if the aircraft are restricted to specific paths but carefully separated.
I hope that rabid proponents of "free flight" are keeping these realities in mind.
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AnthonyGA,
if you are interested in the statistics, then you might wish to read the Patlovany paper which I referenced in my earlier post
It appeared in the major journal Risk Analysis and comes closer to addressing the original question than most other posts here. This thread seems to me to be more about anecdotes than it does about answering the original question.
PBL
if you are interested in the statistics, then you might wish to read the Patlovany paper which I referenced in my earlier post
It appeared in the major journal Risk Analysis and comes closer to addressing the original question than most other posts here. This thread seems to me to be more about anecdotes than it does about answering the original question.
PBL
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ive flown inbound to an airport and when i called up the tower, he asked me if i was the one at 1100 feet or the one at 3000 feet.. the dots on the screen were overlapping and neither of us knew the other one was there...
Psychophysiological entity
In about 1961, I was training in an Auster and had just left SEN., still talking to them on the radio. My instructor had let me loose having told me to stop doing all the things I liked doing, put a line on a map, and b
y well follow it for once in my misbegotten life.
At 2,000' I was still in SEN's circle, (via an odd procedure to let a DAK in) and looked down at the map. When I looked up into the 10+ viz, I saw an American Air-force owned Tripacer pass under me. It was so near that the aerial must have come close to brushing my wheels. I thought bollox to maps, and they later got a bollocking.
Just goes to prove, the MkI eyeball is only of use when pointed in the right direction.
y well follow it for once in my misbegotten life. At 2,000' I was still in SEN's circle, (via an odd procedure to let a DAK in) and looked down at the map. When I looked up into the 10+ viz, I saw an American Air-force owned Tripacer pass under me. It was so near that the aerial must have come close to brushing my wheels. I thought bollox to maps, and they later got a bollocking.
Just goes to prove, the MkI eyeball is only of use when pointed in the right direction.
Why we Worry
rsiano:
My name is not Alfred, and I worried plenty. One of the reasons midairs are so rare is that we do worry, and thus keep a look out, and we avoid them. See and avoid. It mostly works.
Closest to a midair I got was in 1988 over Padre Island, doing spins in the MOA/training area. Typical South Texas sunny, hazy day. Our "box" was 5500-10,000 feet vertically. As usual, we made the 99 call on Uniform (no victor in those aircraft) did the clearing turns, and looked high, center, and low for traffic. Clear. Up we go, stall, spin, down we tumble, recover, and as we pull up I spot (rather close) a brown flash going right to left. Take controls, evade, dive, avoid, continue turn, full throttle, give chase.
I spotted him easily, straight and level, heading north along the beach line. No way he ever saw us, but man, we had been very close.
I decided to find out what was going on. I closed to a parade position, read off his side number to our radar advisory service, and backed away. He stayed S & L the whole time. Oblivious to us. Given that it was a warning area, he was certainly within his rights to be flying along the beach. (Hope PIC was awake ... )
Radar site had this info for me: no squawk 1200, no paint on him until I joined up and called in his side number. The said they'd call FSS and let the guy know.
Here is what galled me: we did what we were supposed to do, look, clear, look, and it still didn't help me or my student spot him before we did our spin.
See and avoid usually works ... but it isn't infallible, which is why we worry, sir. I wonder if that light civil crew had someone named Alfred at the controls.
My name is not Alfred, and I worried plenty. One of the reasons midairs are so rare is that we do worry, and thus keep a look out, and we avoid them. See and avoid. It mostly works.
Closest to a midair I got was in 1988 over Padre Island, doing spins in the MOA/training area. Typical South Texas sunny, hazy day. Our "box" was 5500-10,000 feet vertically. As usual, we made the 99 call on Uniform (no victor in those aircraft) did the clearing turns, and looked high, center, and low for traffic. Clear. Up we go, stall, spin, down we tumble, recover, and as we pull up I spot (rather close) a brown flash going right to left. Take controls, evade, dive, avoid, continue turn, full throttle, give chase.
I spotted him easily, straight and level, heading north along the beach line. No way he ever saw us, but man, we had been very close.
I decided to find out what was going on. I closed to a parade position, read off his side number to our radar advisory service, and backed away. He stayed S & L the whole time. Oblivious to us. Given that it was a warning area, he was certainly within his rights to be flying along the beach. (Hope PIC was awake ... )
Radar site had this info for me: no squawk 1200, no paint on him until I joined up and called in his side number. The said they'd call FSS and let the guy know.
Here is what galled me: we did what we were supposed to do, look, clear, look, and it still didn't help me or my student spot him before we did our spin.
See and avoid usually works ... but it isn't infallible, which is why we worry, sir. I wonder if that light civil crew had someone named Alfred at the controls.
T-34 just West of Catalina Island off SOCAL coast, June, 1994. Looked down to check a chart, looked up to see a canopy full of a twin cessna, looked about the size of 777. Not far from a VOR, which it appeared to be heading towards. Became a big believer in flight following from ATC.
Yes, mid-airs are something to worry about.
Yes, mid-airs are something to worry about.
Lonewolf 50:
If you haven't already read my posting #8, then please do so for I could not agree with you more.
My life almost ended in similar circumstances.
I was in the right seat of a military 4-engined aeroplane going round "our" published holding pattern at 3,000 feet. I was PNF and, as such, responsible for the lookout as my leader was "on instruments". Due to the design of the aeroplane, there was a strip of windows in front of us therefore, from the right seat I cannot see what is coming up behind us.
The VC-10 concerned came up our left side at exactly the same altitude from our seven o'clock (so could not possibly have been seen).
They never saw us. In very slow motion I watched the jet efflux continue into the distance with not even a one degree heading change.
What was the result of this very near miss?
The crew of the VC-10 was a mixture of BOAC and the Manufacturers. They were on their way from the manufacturer's airfield (Wisley) to practice "blind landings" (CAT 111) at RAE Bedford. It was such a nice day that they decided to proceed VFR (no radar control in those days) at 3,000 feet.
Since our (very busy) military airfield only had an ATZ of 2,000 feet and 2 nms and they were at 3,000 feet, they didn't even see the necessity to even call ATC on the way past. They stated in the report that they "did not even recognise our holding pattern".
That would have been fine but if you decide to fly something like a VC-10 at low level then you need to have your eyes out like organ stops.
They didn't even see us.
We were very lucky and so were they although they never ever realised it!
If you haven't already read my posting #8, then please do so for I could not agree with you more.
My life almost ended in similar circumstances.
I was in the right seat of a military 4-engined aeroplane going round "our" published holding pattern at 3,000 feet. I was PNF and, as such, responsible for the lookout as my leader was "on instruments". Due to the design of the aeroplane, there was a strip of windows in front of us therefore, from the right seat I cannot see what is coming up behind us.
The VC-10 concerned came up our left side at exactly the same altitude from our seven o'clock (so could not possibly have been seen).
They never saw us. In very slow motion I watched the jet efflux continue into the distance with not even a one degree heading change.
What was the result of this very near miss?
The crew of the VC-10 was a mixture of BOAC and the Manufacturers. They were on their way from the manufacturer's airfield (Wisley) to practice "blind landings" (CAT 111) at RAE Bedford. It was such a nice day that they decided to proceed VFR (no radar control in those days) at 3,000 feet.
Since our (very busy) military airfield only had an ATZ of 2,000 feet and 2 nms and they were at 3,000 feet, they didn't even see the necessity to even call ATC on the way past. They stated in the report that they "did not even recognise our holding pattern".
That would have been fine but if you decide to fly something like a VC-10 at low level then you need to have your eyes out like organ stops.
They didn't even see us.
We were very lucky and so were they although they never ever realised it!
JW411:
Read it, and appreciate your amplification as well.
In re PNF and lookout, a problem with that cost me a friend, in 1981, and five others I didn't know so well when their two T-44's ran into one another in and around the landing pattern at an outlying field (Cabaniss Field) in Corpus Christi, Texas. RIP Ensign Jones.
Lonewolf 50:
If you haven't already read my posting #8, then please do so for I could not agree with you more.
If you haven't already read my posting #8, then please do so for I could not agree with you more.
In re PNF and lookout, a problem with that cost me a friend, in 1981, and five others I didn't know so well when their two T-44's ran into one another in and around the landing pattern at an outlying field (Cabaniss Field) in Corpus Christi, Texas. RIP Ensign Jones.
Dog Tired
Guy came back with damaged wingtip, did´nt know how happened....
on another airfield there was the other guy wondering, why his wingtank was looking weired, both had met and hadn´t noticed anything.....
on another airfield there was the other guy wondering, why his wingtank was looking weired, both had met and hadn´t noticed anything.....
Also, have to add, I lost a very dear friend to a mid-air (2 Harriers).
In the early '70's when I was doing my initial flight training I was with my instructor making some approaches into a medium-sized FAA towered airport which was about 10 miles from my small airport base, which was non-towered.
The purpose was to sharpen my radio skills and to get some experience in a controlled environment.
I had about 10 hrs previously in a J-3, then had moved and transitioned into a C150, then had solo-ed and had quite a few hours in the local practice area.
I had not had any scary flights up until this next one
I was flying and on final when I thought I heard our callsign, I was just about to pick up the mic and say "say again"? when my instructor took the column, said "my plane" and banked us hard right !!! ...about 5 seconds later an OV-10 went past us on the left making an instrument approach !!!!
The purpose was to sharpen my radio skills and to get some experience in a controlled environment.
I had about 10 hrs previously in a J-3, then had moved and transitioned into a C150, then had solo-ed and had quite a few hours in the local practice area.
I had not had any scary flights up until this next one
I was flying and on final when I thought I heard our callsign, I was just about to pick up the mic and say "say again"? when my instructor took the column, said "my plane" and banked us hard right !!! ...about 5 seconds later an OV-10 went past us on the left making an instrument approach !!!!
fantom
When was that, Retired? I might be able to help...
Also, have to add, I lost a very dear friend to a mid-air (2 Harriers).
When was that, Retired? I might be able to help...
Also, have to add, I lost a very dear friend to a mid-air (2 Harriers).
A bit OT, but scary as hell. On a strafing event on Frasca Range i was rolling out on final, called "3 is in hot", when out of nowhere about 15 meters to my left another phantom let loose a stick of lead with his vulcan gun. Somehow the No. 4 aircraft had f....ed up and had cut me off. Clear blue sky, standard range pattern.....
The worrying thing about midair potential is, you dont know when it will happen and from which direction.
franzl
Last edited by RetiredF4; 9th Jun 2010 at 22:22.
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rsiano is talking out his rsiano - so...
...give yourselves a 45-minute break and tune into this. It's David Gunson, the 1981 "What goes up might come down" routine. Brilliant! 
David Gunson "What goes up might come down" From 1981, Former air traffic contoler tells us how to fly a plane. maddog77 on USTREAM. Birds
David Gunson "What goes up might come down" From 1981, Former air traffic contoler tells us how to fly a plane. maddog77 on USTREAM. Birds
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Well I Guess We should Not Worry About Positon And Hold Also,
By The Time We Get There, They Will Be Gone, All That Space On The Runway And All.
It Seemed To Work In The Largest Aircraft Accident In History....
By The Time We Get There, They Will Be Gone, All That Space On The Runway And All.
It Seemed To Work In The Largest Aircraft Accident In History....
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EK Gann
PTH, knew Gann slightly aboard the Strumpet on San Juan Island from numerous casual encounters. Ernest had the definition of the best yacht: It's a vessel that drinks 6, feeds 4 and sleeps 2. Being a pilot and a writer myself, we never talked business, just boats, but a gentleman he were.
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Sometimes you do not even see the one you're intercepting!
Mid 70s, Capt 'Jock' was flying in a bunch of divers from Amsterdam to Paull airfield on the North Sea coast(a small grass strip from where Bristows would shuttle them out to the oil rigs). It was night time, he was about 2hrs late on his filed flight plan and someone decided that they would have a bit of fun and send a a fast jet out to identify him. I guess there is not much overlap between the cruise speed of his Aztec and the stall speed of the jet but it nibbled off a bit of his wing tip and then came back for a second look. He thought he was going to be finished off but it became clear that the jet had not even seen him first time around even though he was what they were sent to intercept.
2- Knew a married couple who flew gliders and never flew together for the sake of the kids. The only near mid-air either had was with the other - they were in different gliders in the same thermal!
2- Knew a married couple who flew gliders and never flew together for the sake of the kids. The only near mid-air either had was with the other - they were in different gliders in the same thermal!
Was in a Partenavia with an instructor doing a single engine climb. I had feeling something was not right. Leant forward and looked up only to see the prop and spinner of a Cessna directly above us heading same direction and speed... We were saved by the almost non existant rate of climb and that ' sixth sence '.
Also once had a windscreen full of a Bell 206 crossing right to left. Can still see the coiled cable from pilots headset.
Also once had a windscreen full of a Bell 206 crossing right to left. Can still see the coiled cable from pilots headset.
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In cloud in a Wessex 5 hit I a Sea Harrier. Saw nothing, felt a LOT! Both survived - put down to air traffic error. Landed in pub car park, borrowed a fiver from the barmaid and had several beers...........
