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#31
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"Teacherjh" wrote in message
... ... unless you can't take off without an IFR clearance, and there's incoming. But I suppose the controller would take care of that when it happened. Ninety-nine times out of a hundred, sure. Who wants to be the hundredth? It just seems that the end of the runway is a bad place to be unless you're ready to go. It is. And no controller can make you sit there. They don't fly the plane. You do. Pete |
#32
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On Tue, 25 Nov 2003 at 21:21:49 in message
, Teacherjh wrote: What were they doing in position for takeoff without an IFR clearance in hand??? Best that you read an extensive report on this terrible accident. For easy reading and lots of detail I would commend: Air Disaster Volume 1 by Macarthur Job Page 164 Chapter 18 Title of chapter "Did he not clear the runway - the Pan American?" That took place March 27, 1977 ISBN 1 875671 11 0 -- David CL Francis |
#33
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On Wed, 26 Nov 2003 at 12:17:22 in message
, Matthew Waugh wrote: To go back to the original crash - at the time the airport was littered with large airliners because the weather in Europe was horrible and they'd all landed there to wait it out. So they were back-taxing aircraft on the active runway because the taxi-ways were full. Weather varies considerably across Europe so it is rare for the weather in Europe to be horrible everywhere. The weather was a vital, but local factor in that accident. Whether the Canary islands are even part of Europe is debatable. Unusually there was cloud and fog in Tenerife. Leaving your generalisation aside the cause of all the congestion was that a small bomb had gone off in the passenger terminal at Las Palmas. There had been a 15 minute warning of that but then there was then a second warning about another bomb. There was little option but to close the airport while a big search was conducted. The many flights approaching at that time had to be diverted and they were sent to Los Rodeos, the other Canary Islands international airport, 50 miles away on the island of Tenerife. It had a single runway and had neither taxi ways nor parking to handle double its normal daily traffic. The apron was fully occupied when the KLM 747 arrived. Then the Pan Am 747 arrived. That is just the starting point for what happened. I am not going through all the rest of it - it is well documented but please get the basics roughly correct. -- David CL Francis |
#34
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"Teacherjh" wrote in message
... Being on the runway without an IFR clearance is not a problem. ... unless you can't take off without an IFR clearance, and there's incoming. But I suppose the controller would take care of that when it happened. It just seems that the end of the runway is a bad place to be unless you're ready to go. Not sure why there's such a strong aversion to this. In Europe at least, the rate-limiting step is often coordination with the facility that will control after departure. The clearance is not issued until that has been done, and the window that that facility wants to open up is usually quite short. Hence it's not unusual at a quiet controlled airport to be given the IFR clearance while lined up on the runway, and a take-off clearance immediately afterwards. If the clearance were given at the hold, it could take minutes to backtrack the runway and get airborne -- it's not unusual to get such a clearance a couple of minutes before the end of a flow management slot. Julian Scarfe |
#35
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"Julian Scarfe" wrote in message
... Not sure why there's such a strong aversion to this. Well, for one, because nearly all fatal collisions between transport aircraft occurred on a runway. [...] Hence it's not unusual at a quiet controlled airport to be given the IFR clearance while lined up on the runway, and a take-off clearance immediately afterwards. I don't think anyone stipulated the "quiet controlled airport". "Controlled" is implied, of course. But this "quiet" was never stated. In the US, "quiet controlled airport" is either an oxymoron by definition, or a relative term applicable to airports where there's still a fair amount of traffic. If the clearance were given at the hold, it could take minutes to backtrack the runway and get airborne -- it's not unusual to get such a clearance a couple of minutes before the end of a flow management slot. Minutes? I've never seen an airport where an airplane would take more than ten or fifteen seconds to get lined up and take off. Not saying they don't exist, of course, but surely it makes more sense to think about the typical case here when talking about general procedures. Pete |
#36
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"Julian Scarfe" wrote in message
... Not sure why there's such a strong aversion to this. "Peter Duniho" wrote in message ... Well, for one, because nearly all fatal collisions between transport aircraft occurred on a runway. That's fair enough. I think there have been at least two landing vs position-and-hold collisions, though I don't think either of them involved waiting for an IFR clearance -- but I take the point. [...] Hence it's not unusual at a quiet controlled airport to be given the IFR clearance while lined up on the runway, and a take-off clearance immediately afterwards. I don't think anyone stipulated the "quiet controlled airport". "Controlled" is implied, of course. But this "quiet" was never stated. In the US, "quiet controlled airport" is either an oxymoron by definition, or a relative term applicable to airports where there's still a fair amount of traffic. Well Tenerife was pretty quiet that day until the collision! It's difficult to tell as I have limited experience of flying in the US, but it didn't seem unusual for minutes to go by without the runway being in use. My last flight in the US involved an unscheduled stop at PAE after a door came open in flight. We landed on the runway and instead of asking us to vacate we got to stop, fix the door and then backtrack on the runway to the end. Does Paine Field count as quiet? If the clearance were given at the hold, it could take minutes to backtrack the runway and get airborne -- it's not unusual to get such a clearance a couple of minutes before the end of a flow management slot. Minutes? I've never seen an airport where an airplane would take more than ten or fifteen seconds to get lined up and take off. Not saying they don't exist, of course, but surely it makes more sense to think about the typical case here when talking about general procedures. Again I can only think of specific cases -- I guess concrete is cheaper in the US. :-) At my home base of Cambridge in the UK, the last paved taxiway to/from the apron is about 2/3 of the way down the 6500 ft runway 05. Thus the 747s that come in for maintenance end up taxying more than 4000 ft on the runway, and they don't like doing that very quickly. It's more common than not for them (and the rest of us for that matter) to get a clearance while backtracking. Julian Scarfe |
#37
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"Julian Scarfe" wrote in message
... It's difficult to tell as I have limited experience of flying in the US, but it didn't seem unusual for minutes to go by without the runway being in use. My last flight in the US involved an unscheduled stop at PAE after a door came open in flight. We landed on the runway and instead of asking us to vacate we got to stop, fix the door and then backtrack on the runway to the end. Does Paine Field count as quiet? I'm based at Paine. It does have its quiet moments, but I wouldn't want to sit on the runway for any extended period of time, not as a general rule. You don't say what kind of airplane you were in, or what the nature of the flight was. I assume that since you say you backtracked on the runway, the airplane must've been pretty small. I personally would not have accepted the offer to backtrack on the runway, not at Paine. Your experience is a good example of a scenario that may or may not be entirely safe. (That said, I'm a bit surprised you needed to backtrack on the runway anyway. Assuming you landed on the long runway, there should have been plenty of room for a stop-and-go. If you landed on one of the shorter ones, the taxiway exits are close enough together that it's hardly a more significant effort to taxi back on an actual taxiway. There's no operational reason that justifies the reduction in safety to backtaxi on any runway at Paine). The bottom line IMHO is that as the pilot, it's hard to know for sure whether current circumstances allow one to safely remain on the runway for extended periods of time, and controllers are falliable. Aviation safety is predicated on the idea that one makes every effort to avoid potentially serious situations, even if those situations rarely result in a problem. In any case, I would certainly never say that one should never wait on the runway, but one ought to only do so when one has VERY good information with respect to what aircraft are actually in the area, a reasonable idea of how long the wait will be, and a good escape plan in case the wait goes longer than expected. And one should do it only when there's a really good reason for doing so (i.e. some benefit that justifies the risk). Furthermore (and more relevant to your original comment) I can *easily* see why there's such a strong aversion to this sort of thing. It's rarely an operational necessity, and when it is, it should still only be undertaken with the same (presumably high degree of) caution used in other areas of flight. The aversion is quite understandable IMHO. Pete |
#38
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"Peter Duniho" wrote in message
... I'm based at Paine. It does have its quiet moments, but I wouldn't want to sit on the runway for any extended period of time, not as a general rule. You don't say what kind of airplane you were in, or what the nature of the flight was. I assume that since you say you backtracked on the runway, the airplane must've been pretty small. I personally would not have accepted the offer to backtrack on the runway, not at Paine. Your experience is a good example of a scenario that may or may not be entirely safe. (That said, I'm a bit surprised you needed to backtrack on the runway anyway. Assuming you landed on the long runway, there should have been plenty of room for a stop-and-go. If you landed on one of the shorter ones, the taxiway exits are close enough together that it's hardly a more significant effort to taxi back on an actual taxiway. There's no operational reason that justifies the reduction in safety to backtaxi on any runway at Paine). It was a Seneca II. A collision would have required: a) that a landing aircraft failed to obtain a clearance to land, and b) that we failed to see a landing aircraft while backtracking, and c) that the controller failed to see a landing aircraft, and d) that the landing aircraft failed to see us, and e) that we tried to occupy the same part of a 9000 x 150 ft runway at the same time. It seemed like a good bet. The bottom line IMHO is that as the pilot, it's hard to know for sure whether current circumstances allow one to safely remain on the runway for extended periods of time, and controllers are falliable. Aviation safety is predicated on the idea that one makes every effort to avoid potentially serious situations, even if those situations rarely result in a problem. Given the uncertainties in estimating risks, I usually hesitate to argue relative safety. But I have to say that if you think it's safer to give up 3000 ft of a 9000 ft runway in a light twin than to backtrack on a runway with the controller's authorization, you either have negligible faith in the abilities of ATC or remarkable faith in the workmanship of TCM. In any case, I would certainly never say that one should never wait on the runway, but one ought to only do so when one has VERY good information with respect to what aircraft are actually in the area, a reasonable idea of how long the wait will be, and a good escape plan in case the wait goes longer than expected. And one should do it only when there's a really good reason for doing so (i.e. some benefit that justifies the risk). Furthermore (and more relevant to your original comment) I can *easily* see why there's such a strong aversion to this sort of thing. It's rarely an operational necessity, and when it is, it should still only be undertaken with the same (presumably high degree of) caution used in other areas of flight. The aversion is quite understandable IMHO. Isn't the next logical step to outlaw position-and-hold? Why would you ever occupy the runway without a clearance to take off? Julian Scarfe |
#39
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"Julian Scarfe" wrote in message
... It was a Seneca II. A collision would have required: a) that a landing aircraft failed to obtain a clearance to land, and No. That's the whole point. A controller may well clear an airplane to land right on top of you. You just don't know. b) that we failed to see a landing aircraft while backtracking, and Not hard if the airplane is behind you. Bi-directional operations at Paine are not uncommon. c) that the controller failed to see a landing aircraft, and Not hard if the controller is distracted dealing with an issue elsewhere at the airport. That said, the controller needs only to fail to see ONE of the aircraft, either the landing one or the sitting-duck one. d) that the landing aircraft failed to see us, and Oddly enough, runway collisions happen. Obviously pilots of other aircraft DO in fact find themselves not being able to see other airplanes on the runway in time to avoid them. e) that we tried to occupy the same part of a 9000 x 150 ft runway at the same time. Funny thing about coincidences. They do exist. A common generalization made about accidents is that they usually involve a relatively long chain of events or decisions. Alter just one, and the entire accident never happened. Even if your chain of events is as unlikely to occur as you think it is (and I don't agree that it is), the point is that the chain of events CAN certainly occur. The one element you have control over is whether you actually get onto the runway and wait for an extended period of time. Why miss that great opportunity to break the chain of events? It's the only one you have. It seemed like a good bet. I'm sure the sequence of events leading up to a great many accidents (aircraft and otherwise) seemed like a good bet at the time. Given the uncertainties in estimating risks, I usually hesitate to argue relative safety. But I have to say that if you think it's safer to give up 3000 ft of a 9000 ft runway in a light twin than to backtrack on a runway with the controller's authorization, you either have negligible faith in the abilities of ATC or remarkable faith in the workmanship of TCM. With respect to my opinion of ATC: I simply don't see the point in trusting them when there's no real need to. I have faith in their abilities, but I prefer to deal in things that I *know* for sure rather than trusting someone else to do them. Too often, a person I trust lets me down. Rarely, my life is at stake, but that is the case here. As far as giving up 3000' of a 9000' runway: a) that's not the only alternative to backtaxiing -- at Paine, all you have to do is get off the runway and taxi back on the parallel taxiway; and b) frankly, AFAIK 6000' is *plenty* of runway from which to launch a Seneca II. I would pick option a) -- using the taxiway -- but if you are really trying to save time and are willing to reduce your safety factor to do it, the stop-and-go is the right solution. Backtaxiing on the runway saves you negligible time compared to taxiing back on the taxiway, while the stop-and-go saves you serious time. Isn't the next logical step to outlaw position-and-hold? Why would you ever occupy the runway without a clearance to take off? As I mentioned, there are times in which it's an appropriate solution. At Paine, the most common reason that clearance is used is when the controller is trying to get as many departures out before the next landing. Allowing an airplane to proceed onto the runway as the preceding airplane is taking off helps this goal. Because the takeoff is expected immediately and the "position and holding" aircraft can see where the landing traffic is, they can evaluate the reasonableness of the clearance. Things are happening fast enough that ANY delay is cause for concern and the pilot can get back off the runway. The problem that started this discussion is one of the length of time an aircraft is expected to sit on a runway. Five, ten, maybe even fifteen seconds to wait for an IFR clearance seems perfectly reasonable. But several minutes? No, not to me it doesn't. Like I said, I'm not going to take so extreme a position as to claim that position-and-hold is NEVER appropriate. But I certainly feel that its use should be restricted to very narrow situations where the hazard has been reduced to the greatest extent possible, and especially to where the pilot doing the position and hold has first-hand knowledge regarding the safety of the operation (as opposed to trusting ATC to take care of everything). Finally, let me remind you that the comment to which I took issue was the "not sure why there's such a strong aversion to this." The bottom line here is that the reason for the aversion is clear. There are definitely safety issues, regardless of how significant you think they are. You might as well say "not sure why there's such a strong aversion to spiders". After all, all but a handful of spiders are safe. Yet, no one should be surprised when they come across another person who has a strong aversion to spiders. It's only natural. Your apparent argument to the contrary is a bit puzzling to me, to say the least. Pete |
#40
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I think we've passed the 80:20 point on this debate so I'll let it rest.
Needless to say I don't agree with all you say, but you've raised some point of which awareness can only be a positive thing for me and other readers. "Peter Duniho" wrote in message ... The problem that started this discussion is one of the length of time an aircraft is expected to sit on a runway. Five, ten, maybe even fifteen seconds to wait for an IFR clearance seems perfectly reasonable. But several minutes? No, not to me it doesn't. No that wasn't what I intended, though I can see why you interpreted it that way. I said it could be minutes between an aircraft receiving an IFR clearance at the hold and being in a position to take off. In most cases I would expect a clearance to come during the backtrack and to be available on turnaround, within seconds. I don't think ATC would leave an aircraft sitting there for minutes unless they anticipated a clearance from another facility that didn't come. Finally, let me remind you that the comment to which I took issue was the "not sure why there's such a strong aversion to this." The bottom line here is that the reason for the aversion is clear. There are definitely safety issues, regardless of how significant you think they are. You might as well say "not sure why there's such a strong aversion to spiders". After all, all but a handful of spiders are safe. Yet, no one should be surprised when they come across another person who has a strong aversion to spiders. It's only natural. Your apparent argument to the contrary is a bit puzzling to me, to say the least. I think you do yourself no favours with that argument as fear of spiders tends to be an irrational fear. You've eloquently outlined the hazards that give rise to your aversion to sitting on the runway for longer than necessary. They are quite rational, even if we disagree about the magnitude of the risk. Julian Scarfe |
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