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 |
#91
|
|||
|
|||
OK, having read through this thread for awhile, I might as well chime in
with a few observations: 1) Roll the dice often enough, and they will eventually come up snake-eyes. The question is whether they are likely to do that before something else gets you. Most people want to make it more likely that they will die of cancer or heart disease than in an airplane crash. Apparently we want to die slowly and old. 2) Here in the Pacific Northwest, flying at night in the mountains is dangerous, no question about it. Indeed, the mountain ranges around here are possibly some of the most dangerous in the world. The trouble is, flying anywhere around here at night as not much better. The whole area is mountainous, heavily forested, with large tracts of water that is barely above freezing year 'round. Visible emergency landing areas at night are few and far between. Low ceilings, low freezing levels, haze, mountain obscuration, micro-climates with weather wildly different from anything forecast -- these are the norm around here. Many students around here manage to log over an hour of actual IFR before they get their private certificate. On top of that, the days get real short and real dark during the winter, so restricting yourself to daytime flight is difficult. 3) Even if you live through an emergency landing at night in this area, the odds of surviving until you are found are vanishingly small, especially considering that most pilots do nothing to increase their chances of survival. They fly without jackets or coats, take no survival gear, have no way of signaling rescuers, etc. You are going to be wet and cold and probably injured. Not good. OK, if you want to die slowly and old, don't fly at night in the Pacific Northwest, especially in the mountains. If you don't want to kill your son or anybody else, don't take them with you when you fly little single engine airplanes at night in the mountains around here. But even if you don't give a rip about yourself or anybody else, I would ask you not to do it anyway. Too many good people are killed every year trying to rescue selfish, thoughtless bozos who thought they were invulnerable to the laws of averages. |
#92
|
|||
|
|||
|
#93
|
|||
|
|||
"George Patterson" wrote in message ... Jose wrote: But you would never say "the Appalachian ranges." For the same reason, you should never say "the Sierras" when you're talking about the Sierra Nevada. But we say "the Appalachians". And it would be correct to say "the Nevadas." But not "the Sierras." George Patterson I prefer Heaven for climate but Hell for company. Correct or not. I live out here and if you said in conversation: I went hiking last weekend in the Sierra. or I think I will go skiing next week in the Sierra or Take I80 over the sierra. You would sound kind of goofy to a local. Howard |
#94
|
|||
|
|||
|
#95
|
|||
|
|||
|
#96
|
|||
|
|||
|
#97
|
|||
|
|||
"Ron Garret" wrote in message
... In article , wrote: I think the implication, with all due respect, in the way you worded your post, is that the probability is increasing as you flying time is increasing. It depends on what you mean by "the probability". There are two different probabilities being discussed: there is the probability of a failure on any particular flight, which doesn't change, and there is the cumulative probability of experiencing failure on some flight, which does change (it increases with each flight). This is clearly not the case, as I think we all now agree. There is also the probability (that Peter (I think) proposed) stated as a cumulative probability in terms of an arbitrary large number of trials (flights, or hours, or whatever). If you convert this to a probability of occcurence with a lower number of trials (flights, or hours, or whatever) that probability will be lower. Looked at it this way, if the probability of an 'occurrence sometime in (the remainder of )one's career is known, then as the career progresses, the probability of 'an occurrence sometime (in the remainder of) one's career diminishes from that value. This is a direct consequence of 1) the premises (accepted by all here, apparently) that - the probability for any given trial (hour, flight, or whatever) is assumed to be independent of any other given trial (hour, flight or whatever) and - the probability is assumed to be the same for each such trial, and 2) the assertion that the probability of an occurrence over n trials is (1-(1-p)^n, where p is the probability of occurence in a single such trial. Its the same problem worked back to front (or front to back, depending on your point of view): i.e.: Let p2 be the probability of an occurence in n2 trials, and let p1 be the probability of an occurence in n1 trials, if n1 n2, then p1 p2. If you *start* with p1, as you consider an increased number of trials the probability will increase, if you *start* with p2 and consider a decreased number of trials, the probability will decrease. Your statement is ambiguous because you don't say which probability you're referring to. Yes. The logical conclusion is determined from the premises used. You only get out of it what you put in. Every day is a new day, and N gets reset to zero. Not quite. Every day is indeed a new day, but with every flight N is incremented by one. It depends on upon from which premise you started. If you're considering your probability in terms of occurences per N trials, you might change N if you start out with it being 'the number of trials in my entire career', but the probability of an occurence 'in the next N trials' otherwise doesn't need any change in N from day to day. But 'the number of trials in my career' is moot in the first place, and I'd argue that arbitrarily specifiying the number of trials that are 'going to occur' in your career is equally problematic, as is coming up with such a probability in the first place. The best you can get out this argument, I think, starting out with a guess for the cumulative probability of the 'entire carreer', is a qualitative 'probability is decreasing' as the career progresses, and you can't really ever quantitatively say how much. |
#98
|
|||
|
|||
In article P68Ud.515993$8l.368458@pd7tw1no,
"Ron McKinnon" wrote: as the career progresses, the probability of 'an occurrence sometime (in the remainder of) one's career diminishes from that value. Yes, but only because N is lower. Whatever N is, after every flight N is 1 less than it was before. But 'the number of trials in my career' is moot in the first place, That is arguable. As a precise number you're probably right. But in broad brushstrokes you can decide, e.g. never to try something, to try something once and then never again, to try something a dozen times in your lifetime, to do something once a month, once a week, once a day, or multiple times a day. Each of these choices entails a monotonically increasing risk of encountering certain kinds of disasters over your lifetime. My personal risk tolerance works out something like this: Things I'm not willing to try even once: heroin, motorcycle racing Things I'm willing to try once in my lifetime and never again: going into space (assuming I ever have the opportunity) Things I'll do a dozen times: aerobatics Once a month (on average): skiing Once a week: Flying GA aircraft Once a day: getting out of bed in the morning :-) Multiple times a day: driving on the freeway, eating sushi :-) rg |
#99
|
|||
|
|||
wrote in message
... [...] the chance is actually only 75%. How so? The probability of both engines failing is .25, I agree, but I'm talking a failure of either engine. I am too. What chance do YOU think you have of having a failure of either engine, if not 75% (in this example)? If the chance of an engine failure is 50% (0.5), then the chance of either engine failing when you have two engines is 1-(0.5)*(0.5). 75%. The probability of both engines failing is indeed only 25%. The probability of EITHER engine failure is 75%. You need to do the subtraction because the chance of an engine failure is actually the opposite of the chance of completing a flight without an engine failure. To make the flight successfully without either engine failing requires BOTH engines to not fail, and the way to calculate that is to multiply the chances of each engine failing (which in this case is just two engines, with identical chances). The chance of you completing the flight without a failure is 25% (50% * 50%), so the chance of an engine failure on the flight is 75%. Pete |
#100
|
|||
|
|||
"Ron Garret" wrote in message
... [...] If you think about it, there is absolutely no difference in the risk calculation between making one flight with four engines and four flights with one engine The difference is that when you make a flight with four engines, you know up front that you're carrying four engines. The calculation based on making four flights with one engine is only useful when you know in advance you're making four flights. I certainly hope to make at least four more flights during my flying career, but it's not certain that I will. Sorry you can't see the difference. It's a crucial element to the question of whether it makes sense to worry about the cumulative odds of an engine failure. Pete |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
Did the Germans have the Norden bombsight? | Cub Driver | Military Aviation | 106 | May 12th 04 07:18 AM |
Night Flying Tips | BoDEAN | Piloting | 7 | May 4th 04 03:22 AM |
"I Want To FLY!"-(Youth) My store to raise funds for flying lessons | Curtl33 | General Aviation | 7 | January 9th 04 11:35 PM |
FORSALE: HARD TO FIND CESSNA PARTS! | Enea Grande | Products | 1 | November 4th 03 12:57 AM |
Headlight for night flying | Paul Tomblin | Piloting | 22 | September 27th 03 09:32 AM |