Displaced Thresholds.
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Displaced Thresholds.
If a runway has a permanently displaced threshold due only to obtacles on the approach, can a pilot legally touch down prior to the displaced threshold if he has safely cleared the obstacles?
If someone knows exactly where the law allowing/prohibiting this is located, that would be of great assistance.
I've found the regulation in the Canadian AIP, but am unable to locate it in any other legal document, JAR or otherwise.
Thanks for your help.
If someone knows exactly where the law allowing/prohibiting this is located, that would be of great assistance.
I've found the regulation in the Canadian AIP, but am unable to locate it in any other legal document, JAR or otherwise.
Thanks for your help.
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So far as I'm aware, the area prior to a displaced THR need not be maintained to the same structural integrity as the area beyond the displaced THR. In this country, the area prior to the displaced THR can be used to line up for take-off, but definitely not for landing.
In any event, you may not be aware of the location of the obstacle that has created the need to displace the THR. Thus it would seem to be most unwise to try to land prior to the THR, as this may entail the use of a different approach path that might conflict with the controlling obstacle. Better to refer to the displaced THR and, therefore, be sure that you and your pax will be safe.
In any event, you may not be aware of the location of the obstacle that has created the need to displace the THR. Thus it would seem to be most unwise to try to land prior to the THR, as this may entail the use of a different approach path that might conflict with the controlling obstacle. Better to refer to the displaced THR and, therefore, be sure that you and your pax will be safe.
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How would you know you've safely cleared the obstacle? Gear still attached?
Why would you want to land before the threshold? Want to prove something?...Anyway you paid for all the rwy,you get no discount for using only half of it...
Brgds....
Why would you want to land before the threshold? Want to prove something?...Anyway you paid for all the rwy,you get no discount for using only half of it...
Brgds....
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Because the runway is contaminated with snow, slush or ice, and 2000 meters is a lot better than 1800, even if you can legally land on 1800m?
Not all of us operate on 3000m+ runways the whole time.
Not all of us operate on 3000m+ runways the whole time.
Moderator
The days of "winging it" have long gone.
Now the catchcry is, or should be, risk assessment, control, and mitigation/minimisation.
(a) There is a risk in landing past a displaced threshold - no argument.
(b) There is a good likelihood that this risk will increase significantly if the runway is contaminated.
(c) Unless fuel is the driving critical factor, the mitigator is to divert, perhaps ?
If one "ducks under", one
(a) loses the benefit of visual or electronic slope guidance
(b) one assumes a higher risk of a heavy landing and/or tailstrike
and so the argument can go on ...
In the first instance, you pays your money and takes your chances ..
and, in the second ... which of the various scenarios would you prefer to have to defend in court after the accident .... ?
Now the catchcry is, or should be, risk assessment, control, and mitigation/minimisation.
(a) There is a risk in landing past a displaced threshold - no argument.
(b) There is a good likelihood that this risk will increase significantly if the runway is contaminated.
(c) Unless fuel is the driving critical factor, the mitigator is to divert, perhaps ?
If one "ducks under", one
(a) loses the benefit of visual or electronic slope guidance
(b) one assumes a higher risk of a heavy landing and/or tailstrike
and so the argument can go on ...
In the first instance, you pays your money and takes your chances ..
and, in the second ... which of the various scenarios would you prefer to have to defend in court after the accident .... ?
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Well, thanks for all the opinons, but noone really answered the question.
The most common reason to displace a threshold is because of obstacles on the approach. If that obstacle is behind you, can you legally touch down on the perfectly maintained, load bearing surface prior to the threshold? If not, where is this LAW stated? If so, where is this law stated?
There are a million reason t want to touch down before a displaced threshold. If a runway is 2500ft long, with a 600ft displaced threshold, and your aircraft requires 1899 ft to stop, that 600 is invaluable.
Many obstacles which are the cause for displaced threshold are off the centerline of the runway, but withing the 5degree cone of approach. As a pilot, it is easy to tell once you've past an obstacle, without bouncing the gear off of it.
Opinions are great, but facts, and quotes are better.
The most common reason to displace a threshold is because of obstacles on the approach. If that obstacle is behind you, can you legally touch down on the perfectly maintained, load bearing surface prior to the threshold? If not, where is this LAW stated? If so, where is this law stated?
There are a million reason t want to touch down before a displaced threshold. If a runway is 2500ft long, with a 600ft displaced threshold, and your aircraft requires 1899 ft to stop, that 600 is invaluable.
Many obstacles which are the cause for displaced threshold are off the centerline of the runway, but withing the 5degree cone of approach. As a pilot, it is easy to tell once you've past an obstacle, without bouncing the gear off of it.
Opinions are great, but facts, and quotes are better.
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I guess it is a case of the law being what the judge delivers in his decision. However, if the start of the LDA is here, and you land before that, does that not suggest that you might be landing other than on the runway ? Whether the surface is seal or not might not be held to be all that important if things go awry ...
Seeing you are in a lovely area ... I think I can guess which hills you are coming over landing toward the sea ... quite a displaced threshold, indeed ... I have some pix tucked away somewhere at home of Otters and Nomads probably 30-40 ft above the cars a long way from the runway ........
Seeing you are in a lovely area ... I think I can guess which hills you are coming over landing toward the sea ... quite a displaced threshold, indeed ... I have some pix tucked away somewhere at home of Otters and Nomads probably 30-40 ft above the cars a long way from the runway ........
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Out of interest to everyone with a negative opinion, the law in Canada (ICAO) can be found at the following link....
http://web.elastic.org/~fche/aip/AIP-01-05-95.html
It clearly states that you CAN land on the surface before the threshold, at least in Canada.
I am very interested in locating any other regulation, JAA, FAA, or otherwise that clearly states a position, negative or positive, as I can't find any.
Any help would be greatly appreciated.
http://web.elastic.org/~fche/aip/AIP-01-05-95.html
It clearly states that you CAN land on the surface before the threshold, at least in Canada.
I am very interested in locating any other regulation, JAA, FAA, or otherwise that clearly states a position, negative or positive, as I can't find any.
Any help would be greatly appreciated.
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(a) in many places, AIP is not law but rather an interpretation by the regulator couched in terms of operational expectation ?
(b) probably it would be sensible not to crash prior to the point at which the particular aircraft had the benefit of ICAO (or local, if more restrictive) approach gradient obstacle clear requirements met ?
At day's end, the pilot has the immediate capability of doing whatever he chooses whether his peers view such as being either sensible or not.
However, it is the judge who determines the penalty, if any, following the enquiry consequent to the accident ...
(b) probably it would be sensible not to crash prior to the point at which the particular aircraft had the benefit of ICAO (or local, if more restrictive) approach gradient obstacle clear requirements met ?
At day's end, the pilot has the immediate capability of doing whatever he chooses whether his peers view such as being either sensible or not.
However, it is the judge who determines the penalty, if any, following the enquiry consequent to the accident ...
Per Ardua ad Astraeus
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I-Ford - I think there were other issues in at least one of the GOA 'incidents' and in view of the amount of metal 'under your feet' on finals there I would be very reluctant to 'land short' on that runway!
IMO if you cannot guarantee stopping in the available runway length - do something else - dire emergencies excluded, of course. The reference you link to clearly says it is the pilot's responsibilty to maintain safety - which is ALWAYS the case, and I can see NO reason to land 'short' in normal ops. I would suggest that the question 'is it legal' is less relevant than 'is it sensible'?
If, OTH, your aircraft can fly, say, a 5 or 6 degree slope, then perhaps you can apply for an alleviation, but equally the types that can do that should not need more than 2100mtrs?
As to whether it is 'legal', I would suggest that you would not encounter a problem from the airport authorities providing the surface is 'suitable', but as is the case of R29 at GOA your operating company may wish you to explain a significant 'below gp' event or a high rate of descent at a late stage - or even worse, a piece of dockyard crane in your undercarriage.
IMO if you cannot guarantee stopping in the available runway length - do something else - dire emergencies excluded, of course. The reference you link to clearly says it is the pilot's responsibilty to maintain safety - which is ALWAYS the case, and I can see NO reason to land 'short' in normal ops. I would suggest that the question 'is it legal' is less relevant than 'is it sensible'?
If, OTH, your aircraft can fly, say, a 5 or 6 degree slope, then perhaps you can apply for an alleviation, but equally the types that can do that should not need more than 2100mtrs?
As to whether it is 'legal', I would suggest that you would not encounter a problem from the airport authorities providing the surface is 'suitable', but as is the case of R29 at GOA your operating company may wish you to explain a significant 'below gp' event or a high rate of descent at a late stage - or even worse, a piece of dockyard crane in your undercarriage.
A steep approach (5-6 deg) should qualify for a reduced threshold crossing height (35 ft), which in turn gives an increased LDA from the geometry.
Duck under – well don’t try that from the ‘city end’ at London City Airport as the bridge and road lights get very close even with a 1:29 OFS.
How do you ever know that you have missed all of the obstacles? A typical human assumption that often precedes errors and accidents; don’t duck under / land before the threshold.
Duck under – well don’t try that from the ‘city end’ at London City Airport as the bridge and road lights get very close even with a 1:29 OFS.
How do you ever know that you have missed all of the obstacles? A typical human assumption that often precedes errors and accidents; don’t duck under / land before the threshold.
The original question had to do with finding specific rules governing the allowed uses of displaced threshold runway surface in various countries, If I understood the question correctly. In the USA, I am unaware of any specific regulation on this subject. However, the AIM guidance on runways and their markings indicate that the runway area prior to the threshold markings (displaced threshold marked by arrows) is not available for landing touchdown, even though it is available for takeoff, taxi and rollout. FAA actions against pilots sometimes cite the pilot's disregard of the AIM guidance on an issue as evidence of a FAR 91.13 "Careless or wreckless" violation even though the FAA officially refer to the AIM as "non-regulatory guidance" or "advisory in nature". In other words, you may not be legally required to follow this "advise", but if something goes wrong....
Runway thresholds may be displaced for any of a variety of reasons other than obstacle clearance plane considerations. These include, but are not limited to, ILS navigation signal integrety requirements, pavement structural strength requirements or even airport neighbor concerns about low flying aircraft and noise. One southern California municipal airport with a stong anti-airport contigient proposed displacing the runway threshold to discourage it's use by jet operators. So far, FAA does not support this course of action.
Under FAA regulations, large and turbine powered aircraft must maintain at or above any electronic or visual glidepath guidance while approaching the runway and may not descend below this path until necessary for safe landing. Vertical guidance is typically aligned so as to provide for a threshold crossing hieght of 50'. Glideslope angle may be raised above the standard 3 deg. and/or the threshold may be displaced to provide required obstacle clearance. On shorter runways, contaminated runways or with adverse wind components, It may sometimes require that vertical flight path angle and aim points be adjusted in order to intersect the runway surface at an acceptable rate of closure at the required touch down point for the situation. These adjustments must still allow conformity with applicable stabilized approach requirements and safe obstacle clearance. Under these conditions, firm touchdowns and maximum allowable braking may be required. Aiming shorter to land sooner or touch down softer IS commonly done by many pilots but it must be understood that there is little defense if something goes wrong. In low visibility conditions or at unfamiliar fields, especially at night, many accidents have been traced to pilots succumbing to visual illusion and hitting obstacles. Intentionally landing short of the threshold marking is not normally viewed as acceptable except in the most extraordinary circumstances of emergency. Normal approach profiles intersect the runway surface at aproximately 700-1000' beyond the threshold marking depending on the specific descent angle. Roundout places the touchdown point somewhere beyond this. The higher above and further forward the pilot sits relative to the main wheels at threshold crossing attitude, the closer to the threshold the mains will touch and the closer the aircraft will pass to any ground obstacle in the flight path.
I realize that the above is not all clear, black letter law, but I hope it is helpful anyway.
Best regards,
Westhawk
Runway thresholds may be displaced for any of a variety of reasons other than obstacle clearance plane considerations. These include, but are not limited to, ILS navigation signal integrety requirements, pavement structural strength requirements or even airport neighbor concerns about low flying aircraft and noise. One southern California municipal airport with a stong anti-airport contigient proposed displacing the runway threshold to discourage it's use by jet operators. So far, FAA does not support this course of action.
Under FAA regulations, large and turbine powered aircraft must maintain at or above any electronic or visual glidepath guidance while approaching the runway and may not descend below this path until necessary for safe landing. Vertical guidance is typically aligned so as to provide for a threshold crossing hieght of 50'. Glideslope angle may be raised above the standard 3 deg. and/or the threshold may be displaced to provide required obstacle clearance. On shorter runways, contaminated runways or with adverse wind components, It may sometimes require that vertical flight path angle and aim points be adjusted in order to intersect the runway surface at an acceptable rate of closure at the required touch down point for the situation. These adjustments must still allow conformity with applicable stabilized approach requirements and safe obstacle clearance. Under these conditions, firm touchdowns and maximum allowable braking may be required. Aiming shorter to land sooner or touch down softer IS commonly done by many pilots but it must be understood that there is little defense if something goes wrong. In low visibility conditions or at unfamiliar fields, especially at night, many accidents have been traced to pilots succumbing to visual illusion and hitting obstacles. Intentionally landing short of the threshold marking is not normally viewed as acceptable except in the most extraordinary circumstances of emergency. Normal approach profiles intersect the runway surface at aproximately 700-1000' beyond the threshold marking depending on the specific descent angle. Roundout places the touchdown point somewhere beyond this. The higher above and further forward the pilot sits relative to the main wheels at threshold crossing attitude, the closer to the threshold the mains will touch and the closer the aircraft will pass to any ground obstacle in the flight path.
I realize that the above is not all clear, black letter law, but I hope it is helpful anyway.
Best regards,
Westhawk
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Let me be a little more specific.
A friend of mine was flying a light aircraft into a 2500 ft strip. This is a day VFR strip, with a permanently displaced threshold of 600 ft, due to obstacles on the approach. The dislacing obstacle is a 600 ft hill, ending 2 miles from the runway. It is very easy to turn final inside the hill, and avoid the obstacle all together, and is common practice at this airfield. The aircraft in question requires about 1800 ft to land at gross, and as this runway has 1900 available, it is perfectly 'legal'.
Long story short, the local authority was watching this particular day and witnessed him touching down before the threshold, and wishes to persecute him for it. Every single aircraft that day, and every day for the last 10 years has touched down before the threshold, but they chose him to penalize.
When he asked the authority where the regulation was located, he was informed that 'it is basic aviation knowledge'.
I personally don't feel that it is 'basic aviation knowledge' and wish to find the truth.
I would be perfect happy with either result. If it's illegal, I can give up my search, and admit defeat. If it's legal, he can point out the mistake to the authority.
Thanks in advance for everyone's help.
A friend of mine was flying a light aircraft into a 2500 ft strip. This is a day VFR strip, with a permanently displaced threshold of 600 ft, due to obstacles on the approach. The dislacing obstacle is a 600 ft hill, ending 2 miles from the runway. It is very easy to turn final inside the hill, and avoid the obstacle all together, and is common practice at this airfield. The aircraft in question requires about 1800 ft to land at gross, and as this runway has 1900 available, it is perfectly 'legal'.
Long story short, the local authority was watching this particular day and witnessed him touching down before the threshold, and wishes to persecute him for it. Every single aircraft that day, and every day for the last 10 years has touched down before the threshold, but they chose him to penalize.
When he asked the authority where the regulation was located, he was informed that 'it is basic aviation knowledge'.
I personally don't feel that it is 'basic aviation knowledge' and wish to find the truth.
I would be perfect happy with either result. If it's illegal, I can give up my search, and admit defeat. If it's legal, he can point out the mistake to the authority.
Thanks in advance for everyone's help.
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If I remember correctly my PPL examiner told me that you can land on a displaced threshold so long as you aren't flying commercially. He actually pulled me up for NOT landing on it (it was runway 09 at Scone Airport, Perth).
I couldn't quote you the actual regulations though...
I couldn't quote you the actual regulations though...
ac500u,
Sorry I did not see the now obvious clues as to the situation you seek information on. I assume from the available clues that this took place in some Carib. Island nation or other. So only the specific rules in effect for the country of registry of the aircraft, the issuing country of the licence held by the pilot and the country where this occurred should be considered when researching the possible specific charges against your friend. If it was a national aviation authority who accuses the pilot of violating a rule, they should provide the specific charge in due course. If a local airport official, perhaps they just seek a "fine" be paid for the transgression. This has only happened to me in Mexico but I have heard of this practice elsewhere as well. If this is a CAA inspector or equivilant, I would advise your friend to consult with an aviation experienced lawyer/barrister before proceeding further.
I wish your friend the best in resolving the matter. Would like to hear how it plays out.
Best regards,
Westhawk
Sorry I did not see the now obvious clues as to the situation you seek information on. I assume from the available clues that this took place in some Carib. Island nation or other. So only the specific rules in effect for the country of registry of the aircraft, the issuing country of the licence held by the pilot and the country where this occurred should be considered when researching the possible specific charges against your friend. If it was a national aviation authority who accuses the pilot of violating a rule, they should provide the specific charge in due course. If a local airport official, perhaps they just seek a "fine" be paid for the transgression. This has only happened to me in Mexico but I have heard of this practice elsewhere as well. If this is a CAA inspector or equivilant, I would advise your friend to consult with an aviation experienced lawyer/barrister before proceeding further.
I wish your friend the best in resolving the matter. Would like to hear how it plays out.
Best regards,
Westhawk
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The local authority down here has there own set of regulations that are loosely based on the older UK CAA regs. They are in a period of transition to new regs based on ICAO standards.
If they had simply said that my friend had broken rule 313.45 found on page 145 of the CARS, we all would've been happy and accepted the error.
However, they said that he broke the law, he said 'which law is that', they said 'it's basic aviation knowledge'. I found it highly insulting, as, if this is 'basic knowledge' then clearly I, and Transport Canada, have no basic knowledge.
I anyone knows where any regulations is located from ANY regulatory body that states that this is legal or illegal, I would greatly appreciate the assistance.
Thanks again.
If they had simply said that my friend had broken rule 313.45 found on page 145 of the CARS, we all would've been happy and accepted the error.
However, they said that he broke the law, he said 'which law is that', they said 'it's basic aviation knowledge'. I found it highly insulting, as, if this is 'basic knowledge' then clearly I, and Transport Canada, have no basic knowledge.
I anyone knows where any regulations is located from ANY regulatory body that states that this is legal or illegal, I would greatly appreciate the assistance.
Thanks again.
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I can't give you a definitive bit of law but I would offer the following (UK) orientated view.
A displaced landing threshold is the start of the runway for a landing aircraft.
It is quite conceivable that if the dimensions are suitable that there may be some other quite legitimate activity going on in the undershoot that the pilot would not be told about - even if the threshold was originally displaced because of an obstacle.
Although I would have expected ICAO to treat the situation in the same way the only reference that I can find in Annex 6 Part 1 is about precision approaches and says "An operator shall establish operational procedures designed to ensure that an aeroplane being used to conduct precision approaches crosses the threshold by a safe margin, with the aeroplane in the landing configuration and attitude."
A displaced landing threshold is the start of the runway for a landing aircraft.
It is quite conceivable that if the dimensions are suitable that there may be some other quite legitimate activity going on in the undershoot that the pilot would not be told about - even if the threshold was originally displaced because of an obstacle.
Although I would have expected ICAO to treat the situation in the same way the only reference that I can find in Annex 6 Part 1 is about precision approaches and says "An operator shall establish operational procedures designed to ensure that an aeroplane being used to conduct precision approaches crosses the threshold by a safe margin, with the aeroplane in the landing configuration and attitude."
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Regarding ' things going on, on the displaced portion that the pilot doesn't know about '... This would have to be covered in a notam. Any change to a runway, whether temporary displacement or otherwise, must be issued in a notam.
Also, if the area is unfit for surface movement of a/c it must be marked with X's or chevrons leading to the displaced threshold (not arrows).
Also, if the area is unfit for surface movement of a/c it must be marked with X's or chevrons leading to the displaced threshold (not arrows).