If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#21
|
|||
|
|||
First-hand video of a BRS deployment.
Jim Carriere wrote:
Bob Moore wrote: Jim Carriere wrote Mxsmanic wrote: Fortunately, mathematics can help. If everyone flies around completely at random, it's statistically wildly improbable that any aircraft will ever collide. In fact, traffic patterns, airways, altitude restrictions, and navaids actually increase the chances of a collision, rather than decreasing This has to be one of the funniest things I've read in a long LONG time! Thanks for the laugh! Sorry Jim, I think that the laugh might be on you. In the late 1950s, the Rand Corp under contract to the US government to study the future of the Air Traffic Control System, came to the exact same conclusion. And yes, they did use predictions of future air traffic growth. Hmm! At first glance that conclusion seems counterintuitive, but I guess you learn something new every day. Actually, it is very intuitive. If I put 100 people on a football field and blind fold them and tell them to just walk around, how often will they run into each other? Now if I put 100 people in a hallway that is 4' wide and 100 yards long and have them randomly walk around, how often will they run into each other? Airways and traffic patterns concentrate the traffic into a much small volume. This will greatly increase the risk of collision and it seems very intuitive to me. Matt |
#22
|
|||
|
|||
First-hand video of a BRS deployment.
Jim Carriere writes:
Hmm! At first glance that conclusion seems counterintuitive, but I guess you learn something new every day. The logic is straightforward. The sky is a big place: 145 million square nautical miles, and at least ten nautical miles deep. That's 1.5 billion cubic nautical miles. A typical GA aircraft might occupy a cube 20 metres on a side (about 1/500,000 of a cubic nautical mile at most). If aircraft truly flew absolutely randomly over the surface of the Earth, the chances of them ever colliding would be so low that no ATC would be needed. Indeed, even visual separation would be largely unnecessary. There just wouldn't be enough of a probability that aircraft would ever be in the same place at the same time to justify any precautions. Thus, all the need for safety and traffic control to avoid midair collisions is engendered by the fact that many aircraft like to fly in the same places as the same time. Airports are the major factor here, as they force aircraft to come into close proximity to take off and land. The problem is then greatly exacerbated by airways and waypoints and fixes, all of which "attract" aircraft to very small fractions of the total airspace. Aircraft are driven to occupy the same altitude slots at the same lateral points at the same time, and traffic separation becomes extremely important and difficult. As navigation improves, the precision of waypoints and fixes and altitude holds improves with it, and narrows the effectively used airspace even further, dramatically increasing the likelihood of two aircraft being in the same place at the same time. Inevitably, and even with the best of precautions, this leads to an increase in the number of midair collisions. Look to see how many midairs have occurred away from any airport or airway, at random altitudes, and you'll see that they are scarce. Most midairs occur because aircraft are trying to operate in the same highly restricted airspace at the same time. In fact, an incident of this type provided much of the impetus for the modern ATC system, when two airliners collided over the Grand Canyon decades ago. Had they been flying _randomly_ over the Grand Canyon, the accident never would have occurred; but since they were flying similar routes to similar reference points at similar altitudes, the chances of them meeting fatally in midair were hugely increased (by many orders of magnitude). And while they had the technology to successfully navigate towards a fairly small, specific spot in the sky, they lacked the technology to avoid colliding with other aircraft. A corollary of this is that, if you are flying VFR in an out-of-the-way place, away from airways and airports and at an unusual or at least random altitude, the chances of you hitting another aircraft are so low that they can actually be ignored (although in practice it doesn't hurt to keep your eyes open). On the other hand, if you have all the latest navigation gizmos and you can accurately guide your aircraft to a 30-foot-wide spot in the sky with them, you had better install TCAS to go with your other gadgets and hope that every other pilot in the same area is similarly equipped. The irony is that navigating accurately greatly increases your chances of hitting someone else unless you also have an equally reliable way of avoiding traffic. Unfortunately, technology for navigation today is outstripping technology for collision avoidance. Looking out the window helps, but I think it safe to say that the rate of collisions will continue to increase until better technological means are found to help avoid collisions. GPS, for example, is going to increase midair accidents, particularly among aircraft that are not equipped with any type of collision-avoidance technology. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#23
|
|||
|
|||
First-hand video of a BRS deployment.
Morgans writes:
But leaving an event up to chance as the avoidance mechanism, is not something that sits well with people. I have to feel that way, in that the results of "winning" the odds are so dire. Yes, but the perception doesn't match the reality. If everyone truly flew around at random (which implies, by the way, that they'd be taking off and landing from their backyards, not from airports that tend to concentrate traffic), traffic avoidance would be a non-issue. Look at it this way: If you and 200 other people go to a cocktail party in a ballroom, what are the chances that you'll bump into someone else during the party? If you are blindfolded (i.e., not actively avoiding traffic), what are the chances that you'll bump into someone? Now put all of those 200 people into the Australian outback. What are the chances of bumping into someone else now? And even if you are blindfolded and wandering at random, what is the danger that you'll bump into someone else? If you're flying away from the crowd, midair collisions aren't much to worry about. Terrain is always down there somewhere, so you have to worry about that. And you have to worry about weather. But you don't have to worry too much about traffic. If you're enjoying your flight puttering around in out-of-the-way areas, you may be the only aircraft in a hundred-mile radius or better, so you can relax. To some extent, GA pilots are lucky in this respect, since they can fly VFR on just about any path they wish. If they choose a lonely area of the country, there's an excellent chance that they'll have all that sky to themselves. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#24
|
|||
|
|||
First-hand video of a BRS deployment.
Mxsmanic wrote:
Jim Logajan writes: I got the following link to this video via the Matronics Zenith e-mail list. What's interesting and fascinating about it is that it contains video from a cockpit camera that shows the impending mid-air collision and the cockpit view when the aircraft hits the ground under the chute: http://www.turbopilot.com/copa/image3/brs.wmv I guess cockpit cameras are becoming common enough that this sort of video would be inevitable. I'm surprised that the pilot believes he is alive today because of the parachute. The aircraft doesn't look severely damaged; the control surfaces are in place. What would have prevented him from gliding to a landing? Because it requires more skill than just typing CTRL-ALT-DELETE you. Don't second guess real pilots. |
#25
|
|||
|
|||
First-hand video of a BRS deployment.
Ron Natalie writes:
Because it requires more skill than just typing CTRL-ALT-DELETE you. How and why would he type Ctrl-Alt-Del? Why not just steer the aircraft to a landing? Don't second guess real pilots. Or else what? -- Transpose mxsmanic and gmail to reach me by e-mail. |
#26
|
|||
|
|||
First-hand video of a BRS deployment.
Richard Riley writes:
Or else you'll be wrong. So I'll be just like many real pilots, who are also wrong. -- Transpose mxsmanic and gmail to reach me by e-mail. |
#27
|
|||
|
|||
First-hand video of a BRS deployment.
On Feb 10, 4:20 pm, "Morgans" wrote:
"Jim Carriere" wrote Hmm! At first glance that conclusion seems counterintuitive, but I guess you learn something new every day. But leaving an event up to chance as the avoidance mechanism, is not something that sits well with people. I have to feel that way, in that the results of "winning" the odds are so dire. Absolute agreement. To me, it's a good reason to be "heads up" when flying over VORs, since they can really concentrate aircraft. Most of us are spending more time on the gauges watching for the arrow to change. Still, maybe it's a non-issue, since we don't seem to hear of lots of collisions around VORs. Seems like mid-airs are mostly around airports. Anyone know the real stats of locations offhand? Thanks, Kev |
#28
|
|||
|
|||
First-hand video of a BRS deployment.
On Feb 10, 7:25 pm, "Kev" wrote:
Still, maybe it's a non-issue, since we don't seem to hear of lots of collisions around VORs. Seems like mid-airs are mostly around airports. Anyone know the real stats of locations offhand? Never mind, I googled it myself, and here's a good summary from the USAF: 1. Mid-air collisions generally occur during weekend daylight hours 56% of the accidents occurred in the afternoon. 32% of the accidents occurred in the morning. 2% of the accidents occurred at night, dusk, or dawn. 2. Most mid-air collisions occur under good visibility. 3. The majority of the aircraft involved in collisions are not on any type of flight plan. 4. Nearly all accidents occur at or near uncontrolled airports and at altitudes below 1000 ft. 5. Flight fatigue is not a major factor in most mid-air collisions. 6. The average flight time prior to the collision is 45 minutes. This time varies from takeoff to over seven hours. 60% of the pilots on the mishap flight had been airborne thirty minutes or less. Only 6% had been flying longer than two hours. 7. Pilots of all experience levels are involved in mid-air collisions, from the first solo ride to 20,000 hour veterans. Kev |
#29
|
|||
|
|||
First-hand video of a BRS deployment.
"Mxsmanic" wrote in message ... Ron Natalie writes: Because it requires more skill than just typing CTRL-ALT-DELETE you. How and why would he type Ctrl-Alt-Del? Why not just steer the aircraft to a landing? He was talking about you, you idiot. If you get in trouble with your computer game, all you have to do is cancel the game. Sheesh, what a numbskull you are. NOTICE!!!! Mxsmanic is NOT a pilot, has NEVER flown an aircraft and is NOT qualified to issue competent information regarding any aspect of the operation of any aircraft. |
#30
|
|||
|
|||
First-hand video of a BRS deployment.
Kev writes:
Still, maybe it's a non-issue, since we don't seem to hear of lots of collisions around VORs. Seems like mid-airs are mostly around airports. Anyone know the real stats of locations offhand? It's probably just a question of numbers. It's much less likely that two aircraft will pass over the same VOR at the same moment and the same altitude than it is that two aircraft will aim for the same runway at the same time from the same direction. If traffic is precisely paced along airways, that could increase the risk, by creating dangerous periods during which multiple aircraft might arrive at the same spot at the same time. Precise traffic control increases safety to the extent that you can control and determine the exact position of all aircraft at the same time, but it also diminishes safety to the extent that you _cannot_ do these things. This implies that there's no one-size-fits-all for aviation traffic control methods, which perhaps has significant implications for the industry, given the periodic transition towards ever more accurate navigation methods (unfortunately without a concomitant transition towards more accurate and reliable anti-collision technologies). -- Transpose mxsmanic and gmail to reach me by e-mail. |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Cirrus chute deployment -- an incredible story | Michael182/G | Instrument Flight Rules | 48 | July 14th 05 03:52 PM |
Parachute fails to save SR-22 | Capt.Doug | Piloting | 72 | February 10th 05 05:14 AM |
North Korea Denounces US Stealth Bomber Deployment | Otis Willie | Military Aviation | 0 | July 2nd 04 09:20 PM |
C-130 Unit Completes Two Year Deployment | Otis Willie | Military Aviation | 0 | September 30th 03 10:04 PM |
Airmen gear up for another 120-day deployment | Otis Willie | Military Aviation | 0 | September 24th 03 12:04 AM |