Displaced Thresholds.
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ac500u
>>Again, I'm in no way advocating 747's landing before displaced thresholds.<<
So, I'm curious, just which aircraft DO you advocate landing before displaced thresholds? Should there be published lists? Not 747's but C172's , ok. What about ATR72's... too big? How about twin otters?
I believe you're clutching at straws trying to make the case for your friend. The fact is that no matter how many times people do something wrong, its still wrong. So far, I have been unable to find a single definition of Landing Distance Available that includes the area before the displaced threshold. I have found many, many references specifically prohibiting it.
Another question springs to mind. If you do not accept the displaced threshold as the beginning of the surface available for landing, what is your understanding of that point? Exactly where do you think its okay to plan touching down? If the unprepared surface short of the runway looks good to you, can you land there too? Is that also type specific, ie, not 747's but "light" aircraft ok?
Aviation and aviation regulation is full of grey areas. Not everything is as black and white as it should be or, in many cases, as it needs to be. In this case, the majority of posts are against landing before the displaced threshold. Technicalities aside and outside emergency situations, I think there would be very few good reasons for doing so.
>>Again, I'm in no way advocating 747's landing before displaced thresholds.<<
So, I'm curious, just which aircraft DO you advocate landing before displaced thresholds? Should there be published lists? Not 747's but C172's , ok. What about ATR72's... too big? How about twin otters?
I believe you're clutching at straws trying to make the case for your friend. The fact is that no matter how many times people do something wrong, its still wrong. So far, I have been unable to find a single definition of Landing Distance Available that includes the area before the displaced threshold. I have found many, many references specifically prohibiting it.
Another question springs to mind. If you do not accept the displaced threshold as the beginning of the surface available for landing, what is your understanding of that point? Exactly where do you think its okay to plan touching down? If the unprepared surface short of the runway looks good to you, can you land there too? Is that also type specific, ie, not 747's but "light" aircraft ok?
Aviation and aviation regulation is full of grey areas. Not everything is as black and white as it should be or, in many cases, as it needs to be. In this case, the majority of posts are against landing before the displaced threshold. Technicalities aside and outside emergency situations, I think there would be very few good reasons for doing so.
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Lanfranc,
Please point me to the "many, many references specifically prohibiting it" which you stated in your post.
I agree that the majority of opinions in this thread favor the side of being illegal, but keep in mind, that's what they are.... opinions.
If you wish to "find a single definition of Landing Distance Available that includes the area before the displaced threshold" as you stated, see my original post with the link to the Canadian AIP which CLEARLY states that it is available. Black and white.
For some reason, you are very upset. You need to relax a little and use some common sense. You ask if I think an unprepared surface is ok to land on too. Is this question really necessary, or are you a little on tilt?
You stated that aviation regulations are full of grey areas. This is one as well. To prosecute some one for something, it generally should be black and white, or common sense.
What is the common sense reason in this case? What in this SPECIFIC case is dangerous about touching down before the threshold. Are the wheels gonna bust through the pavement? Is it possible to hit an obstacle that is 2 miles behind you?
What are the inherent dangers of touching down past the threshold? Wet runway? Bad brakes? Beta Failure? Wind shear? Deep ocean of the end? Once again, several aircraft have run off the end after touching down past the threshold. None (zero) have ever run off after touching down before.
If you relax a little and read more of the relavent posts, you'll see that I was never generalizing that it is ok the land before a threshold at any random airport. I am talking about a specific case. And in this specific case, if you choose to land past the displaced threshold everytime, it will only be a matter of time before you run off the end.
But, we are talking about black and white so again Lanfranc, PLEASE POINT ME TO THE ""many, many references specifically prohibiting it"
Please point me to the "many, many references specifically prohibiting it" which you stated in your post.
I agree that the majority of opinions in this thread favor the side of being illegal, but keep in mind, that's what they are.... opinions.
If you wish to "find a single definition of Landing Distance Available that includes the area before the displaced threshold" as you stated, see my original post with the link to the Canadian AIP which CLEARLY states that it is available. Black and white.
For some reason, you are very upset. You need to relax a little and use some common sense. You ask if I think an unprepared surface is ok to land on too. Is this question really necessary, or are you a little on tilt?
You stated that aviation regulations are full of grey areas. This is one as well. To prosecute some one for something, it generally should be black and white, or common sense.
What is the common sense reason in this case? What in this SPECIFIC case is dangerous about touching down before the threshold. Are the wheels gonna bust through the pavement? Is it possible to hit an obstacle that is 2 miles behind you?
What are the inherent dangers of touching down past the threshold? Wet runway? Bad brakes? Beta Failure? Wind shear? Deep ocean of the end? Once again, several aircraft have run off the end after touching down past the threshold. None (zero) have ever run off after touching down before.
If you relax a little and read more of the relavent posts, you'll see that I was never generalizing that it is ok the land before a threshold at any random airport. I am talking about a specific case. And in this specific case, if you choose to land past the displaced threshold everytime, it will only be a matter of time before you run off the end.
But, we are talking about black and white so again Lanfranc, PLEASE POINT ME TO THE ""many, many references specifically prohibiting it"
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Ok ac500u, I'll humour you one more time. We're talking about an airport with ATC, right? ATC control what is going on on the manoeuvring area, they know about everything that's going on. They'll tell you about anything that you need to know about based on what you are expected to do (or have been cleared to do).
In the hypothetical situation that I mentioned earlier - where the displaced threshold is so far down the runway that anything on the normal/take-off threshold is outside all of the obstaclre clearance surfaces and runway strip - I could, for example allow a vehicle to cross the normal threshold...and I may not bother telling you about it. I've cleared you to land and I'm going to assume that you'll aim to land past the displaced threshold because that's the bit of runway that's notified as available for landing. In strict terms, if you land short of the displaced threshold, it's little different to landing on another runway. You wouldn't land on a different runway to the one you're cleared to land on, would you? Even if you could see there was nothing else on the runway?
As to the NOTAM thing. I'm not going to NOTAM a runway crossing. And I'm not going to NOTAM that the approach lights will be u/s for half an hour on a glorious sunny afternoon whilst some maintenance is done. Why not? Because there's ATC and I'll tell you about it if you need to know - see above about basing what you need to know on what you've been cleared to do. If it was an uncontrolled field things would be different - stuff would have to be NOTAMed because it's possible that no-one at the field will be able to tell you about it. But we're talking about an airport with ATC.
You cite the warning in the Denham entry in the UK AIP. In the UK the AIP is an information publication (I guess the title gives it away a bit), airports can put pretty much anything relevant in their entry. It's probably there because some idiot chose to ignore the markings and caused a problem.
Airmanship or good aviation practise seems rarely to be explicit in law - it's very difficult to define anyway. In the UK there is legislation - ANO articles 63 and 64 - that says you mustn't endanger the aircraft or anyone else. It's a matter of interpretation as to whether any particular action constitutes endangering and definitive interpretation is the one decided in court. I would guess that many other states have something similar. If you want to try and avoid being accused of endangering I would suggest you follow the rules as the majority interpret them.
I'm afraid I tend to agree LanFranc both with the point he makes in his latest post and with the conclusion that your friend is clutching at staws and is going to have to accept that he may be wrong on this one - and, hopefully, before he does any real damage!
In the hypothetical situation that I mentioned earlier - where the displaced threshold is so far down the runway that anything on the normal/take-off threshold is outside all of the obstaclre clearance surfaces and runway strip - I could, for example allow a vehicle to cross the normal threshold...and I may not bother telling you about it. I've cleared you to land and I'm going to assume that you'll aim to land past the displaced threshold because that's the bit of runway that's notified as available for landing. In strict terms, if you land short of the displaced threshold, it's little different to landing on another runway. You wouldn't land on a different runway to the one you're cleared to land on, would you? Even if you could see there was nothing else on the runway?
As to the NOTAM thing. I'm not going to NOTAM a runway crossing. And I'm not going to NOTAM that the approach lights will be u/s for half an hour on a glorious sunny afternoon whilst some maintenance is done. Why not? Because there's ATC and I'll tell you about it if you need to know - see above about basing what you need to know on what you've been cleared to do. If it was an uncontrolled field things would be different - stuff would have to be NOTAMed because it's possible that no-one at the field will be able to tell you about it. But we're talking about an airport with ATC.
You cite the warning in the Denham entry in the UK AIP. In the UK the AIP is an information publication (I guess the title gives it away a bit), airports can put pretty much anything relevant in their entry. It's probably there because some idiot chose to ignore the markings and caused a problem.
Airmanship or good aviation practise seems rarely to be explicit in law - it's very difficult to define anyway. In the UK there is legislation - ANO articles 63 and 64 - that says you mustn't endanger the aircraft or anyone else. It's a matter of interpretation as to whether any particular action constitutes endangering and definitive interpretation is the one decided in court. I would guess that many other states have something similar. If you want to try and avoid being accused of endangering I would suggest you follow the rules as the majority interpret them.
I'm afraid I tend to agree LanFranc both with the point he makes in his latest post and with the conclusion that your friend is clutching at staws and is going to have to accept that he may be wrong on this one - and, hopefully, before he does any real damage!
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Lanfranc,
There is much more to sound arguments / discussion than sarcasm, which you seem to enjoy.
You made several statements in your article, I asked you to verify their location, and you returned with sarcasm.
Is that the sound argument you were referring to?
Again, please point out the 'many, many references specifically prohibiting it' that you mentioned in your post.
It's very simple, you point them out, and I'm dead wrong.
It's doesn't seem like a difficult argument to win (if your correct).
Spitoon, I more clearly see your point, however, tend in this instance to disagree. Would you as an ATC advise anything under your control to cross any portion of a 2500ft strip, when an aircraft is landing? Not from a legal point, but practically? Imagine if it was uncontrolled, what would stop a vehicle from crossing that portion? Nothing really, but that's why we keep our eyes peeled for obstacles on landing, whether aircraft, vehicles, animals, or debris.
Again from a practical point of view. There are many aircraft which land on this runway everyday. Well, not that many, maybe 20-30 landings a day. Every single one of them touch down before the displaced threshold. They are aircraft of several countries, with pilots of several nationalities. Do you suggest that we all land before because we are all reckless? and we all constantly endangerous the lives of our passengers? I'm not saying that because everyone does it, that it's legal, but I am saying that everyone does it because it is safer.
It seems everyone is getting bothered by this. I think that everyone is seeing this from an airliner point of view as Lanfranc is. There is a world of difference between flying a A320, and a light aircraft. I've landed light aircraft on frozen lakes, beaches, and 700ft bushstrips. I still can't grasp how landing 200 ft before a strip of paint on a excellent piece of concrete is inherently unsafe. Again, that's from a practical point of view, not a legal one.
I see the practical and legal arguments as two completely different things.
I personally cannot agree that in this instance it is practically unsafe.
I would be glad to admit that it might not be 'legal' as defined by local regulations. I just can't find anywhere where it clearly states this position.
It might be 'clutching at straws' like you suggest, but I believe that can be viewed both ways. I think saying that anything is illegal with out there being a specific law, is somewhat clutching as well.
There is much more to sound arguments / discussion than sarcasm, which you seem to enjoy.
You made several statements in your article, I asked you to verify their location, and you returned with sarcasm.
Is that the sound argument you were referring to?
Again, please point out the 'many, many references specifically prohibiting it' that you mentioned in your post.
It's very simple, you point them out, and I'm dead wrong.
It's doesn't seem like a difficult argument to win (if your correct).
Spitoon, I more clearly see your point, however, tend in this instance to disagree. Would you as an ATC advise anything under your control to cross any portion of a 2500ft strip, when an aircraft is landing? Not from a legal point, but practically? Imagine if it was uncontrolled, what would stop a vehicle from crossing that portion? Nothing really, but that's why we keep our eyes peeled for obstacles on landing, whether aircraft, vehicles, animals, or debris.
Again from a practical point of view. There are many aircraft which land on this runway everyday. Well, not that many, maybe 20-30 landings a day. Every single one of them touch down before the displaced threshold. They are aircraft of several countries, with pilots of several nationalities. Do you suggest that we all land before because we are all reckless? and we all constantly endangerous the lives of our passengers? I'm not saying that because everyone does it, that it's legal, but I am saying that everyone does it because it is safer.
It seems everyone is getting bothered by this. I think that everyone is seeing this from an airliner point of view as Lanfranc is. There is a world of difference between flying a A320, and a light aircraft. I've landed light aircraft on frozen lakes, beaches, and 700ft bushstrips. I still can't grasp how landing 200 ft before a strip of paint on a excellent piece of concrete is inherently unsafe. Again, that's from a practical point of view, not a legal one.
I see the practical and legal arguments as two completely different things.
I personally cannot agree that in this instance it is practically unsafe.
I would be glad to admit that it might not be 'legal' as defined by local regulations. I just can't find anywhere where it clearly states this position.
It might be 'clutching at straws' like you suggest, but I believe that can be viewed both ways. I think saying that anything is illegal with out there being a specific law, is somewhat clutching as well.
Last edited by ac500u; 30th Jul 2005 at 04:42.
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I guess the only way we're ever going to get a real and legal decision will be when (or if) the regulatory authority takes your friend to court. Decisions made there are the ony ones that truly matter. I wish your friend luck because I think he's going to need it.
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Landing distance requirements, JAR-OPS 1.515
The landing distance required on a dry runway for destination and alternate aerodromes from 50ft to a full stop must not exceed:
a) 60% of the LDA for turbo-jet aeroplanes
b) 70% of the LDA for turboprop aeroplanes
Now, considering that the LDA is a runway available after threshold or displaced threshold the runway length in your case is inadequate.
I'm surprised that the local ATC has not filed the report of those pilots who land before the displaced threshold, because at least where I'm located that would be the case. It is definitely PROHIBITED.
Best Regards,
-AM-
The landing distance required on a dry runway for destination and alternate aerodromes from 50ft to a full stop must not exceed:
a) 60% of the LDA for turbo-jet aeroplanes
b) 70% of the LDA for turboprop aeroplanes
Now, considering that the LDA is a runway available after threshold or displaced threshold the runway length in your case is inadequate.
I'm surprised that the local ATC has not filed the report of those pilots who land before the displaced threshold, because at least where I'm located that would be the case. It is definitely PROHIBITED.
Best Regards,
-AM-
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Thanks I-ford, I think you're the first to see my point.
Approaching minimums, as you quoted, as per the 'numbers' the aircraft does meet the minimum requirements, as follows......
2500ft runway, 600ft displacement, 1900 ft 'available'. 70% of 1900 is 1330. The aircraft in question requires ~1200 as per the manual. (although this is next to impossible).
I'm in full agreement that where you are it might be prohibited, but do you have any documents that clearly state this regulation? If you do, please send me a link.
Also, regarding ATC not filing reports, there is obviously a reason. Possibilities are that it's either not illegal (as in Canada), or they don't wish to close the airport. If they were to file reports on every single aircraft that lands (like I mentioned earlier, ever single aircraft at this airport lands before the displaced threshold), I have to assume that this would effectively close the airport.
I get the impression that alot of people here think that it's just one ignorant pilot landing before a displaced threshold for no reason. I assure you that is not the case. It is every single pilot, every single landing. All nationalities, all registrations. Chief Pilots, training captains, and CAA examiners. That has to be hundreds if not thousands of pilots over the years. Statistics would suggest that we can't all be ignorant psychopaths.
Approaching minimums, as you quoted, as per the 'numbers' the aircraft does meet the minimum requirements, as follows......
2500ft runway, 600ft displacement, 1900 ft 'available'. 70% of 1900 is 1330. The aircraft in question requires ~1200 as per the manual. (although this is next to impossible).
I'm in full agreement that where you are it might be prohibited, but do you have any documents that clearly state this regulation? If you do, please send me a link.
Also, regarding ATC not filing reports, there is obviously a reason. Possibilities are that it's either not illegal (as in Canada), or they don't wish to close the airport. If they were to file reports on every single aircraft that lands (like I mentioned earlier, ever single aircraft at this airport lands before the displaced threshold), I have to assume that this would effectively close the airport.
I get the impression that alot of people here think that it's just one ignorant pilot landing before a displaced threshold for no reason. I assure you that is not the case. It is every single pilot, every single landing. All nationalities, all registrations. Chief Pilots, training captains, and CAA examiners. That has to be hundreds if not thousands of pilots over the years. Statistics would suggest that we can't all be ignorant psychopaths.
