MSA over the sea
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Skydriller,
I am not current on the North Sea at the moment and have never flown front seat in the Dutch Sector (although I have been a pax there once or twice) so I can't comment why one company flies when the other doesn't. I am not sure that it is appropriate to describe a company specific approach procedure on a public forum.
I agree with McMurphy. What might be legal may not be safe. I don't see anything wrong with descending to MSA (and I stand by an MSA of 1500') to break cloud. But how many private/GA pilots have the equipment (radalt, radar, audio/visual alerting device, autopilot etc), training and experience that commercial aviation deems necessary to carry out these approaches safely? It is far easier to become spatially disorientated over water than over land. 500' over the sea is not the place to get the leans either.
I am not current on the North Sea at the moment and have never flown front seat in the Dutch Sector (although I have been a pax there once or twice) so I can't comment why one company flies when the other doesn't. I am not sure that it is appropriate to describe a company specific approach procedure on a public forum.
I agree with McMurphy. What might be legal may not be safe. I don't see anything wrong with descending to MSA (and I stand by an MSA of 1500') to break cloud. But how many private/GA pilots have the equipment (radalt, radar, audio/visual alerting device, autopilot etc), training and experience that commercial aviation deems necessary to carry out these approaches safely? It is far easier to become spatially disorientated over water than over land. 500' over the sea is not the place to get the leans either.
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There is also the approach ban to considder whan making an approach to land i.e. you can not descend lower than 1000ft above the runway unless the minima are above the landing minima.
On a home made approach to an airfield with no met observer, how can you tell what the actual weather is below the cloud you are about to descend into?
Thus unless you can see the weather for yourself i.e. you are below cloud and can assess the visibility by 1000ft you are caught by the approach ban and can't realy even start the approach.
Regards,
DFC
On a home made approach to an airfield with no met observer, how can you tell what the actual weather is below the cloud you are about to descend into?
Thus unless you can see the weather for yourself i.e. you are below cloud and can assess the visibility by 1000ft you are caught by the approach ban and can't realy even start the approach.
Regards,
DFC
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On a home made approach to an airfield with no met observer, how can you tell what the actual weather is below the cloud you are about to descend into?
You descend and look?
You descend and look?
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Thus unless you can see the weather for yourself i.e. you are below cloud and can assess the visibility by 1000ft you are caught by the approach ban and can't realy even start the approach.
Approach bans are stupid things anyway, why not have a go, if you can't get in, go missed and divert......Or maybe this is too much for some people....
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Someone mentioned a radar altimeter.
On "private" instrument approaches, are the CAA-authorised operators required to use a radalt? That would seem most unusual. Even Cat 2 and Cat 3 approaches do not require the pilot to look at the radalt. The autopilot sure uses a radar altimeter to do the last stage of an autoland approach, but on any manual approach the pilot still uses the standard altimeter for the DA decision.
A radalt would be extremely handy for DIY approaches though.
On "private" instrument approaches, are the CAA-authorised operators required to use a radalt? That would seem most unusual. Even Cat 2 and Cat 3 approaches do not require the pilot to look at the radalt. The autopilot sure uses a radar altimeter to do the last stage of an autoland approach, but on any manual approach the pilot still uses the standard altimeter for the DA decision.
A radalt would be extremely handy for DIY approaches though.
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The radalt is of more use over the sea especially when there is no one to give you a QNH (although most platforms provide a QNH). More importantly though is that the RADALT feeds the audio/visual alerting device.
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aha. Found it! Here is the authorities word on unpublished approach minima...
From UK AIP AD 1.1.18
Again note - 1000' above highest obstacle - so even over the sea - as I said - you are looking at 1300' AGL (well AMSL if you are talking about let down over the sea but lets face it that means you must be nowhere near land - so if you go anywhere near land you are actually looking at 1400' AMSL as a minimum)...
From UK AIP AD 1.1.18
11 Aerodromes without published Instrument Approach Procedures
For an aircraft landing at an aerodrome without an instrument approach procedure either:
a A descent should be made in VMC until in visual contact with the ground, then fly to the destination;
b An IAP at a nearby aerodrome should be flown and proceed as in (a); or
c If neither (a) nor (b) is possible, first obtain an accurate fix and then descend not lower than 1000 ft above the highest
obstacle within 5 nm (8 km) of the aircraft. If visual contact (as at (a) above) has not been established at this height, the
aircraft should divert to a suitable alternate with a published instrument approach procedure.
For an aircraft landing at an aerodrome without an instrument approach procedure either:
a A descent should be made in VMC until in visual contact with the ground, then fly to the destination;
b An IAP at a nearby aerodrome should be flown and proceed as in (a); or
c If neither (a) nor (b) is possible, first obtain an accurate fix and then descend not lower than 1000 ft above the highest
obstacle within 5 nm (8 km) of the aircraft. If visual contact (as at (a) above) has not been established at this height, the
aircraft should divert to a suitable alternate with a published instrument approach procedure.
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Absolutely. Thats why I said as a minimum...
Its an interesting thought though isnt it - does that mean a moving object over the sea > 300' should be NOTAMd?
A curious thought isnt it - how can we pilots ensure our safety if we have not been presented with all the information we need...Id love for someone at the CAA to comment about the consideration of moving object hazards whilst engaged in overwater flight...
Its an interesting thought though isnt it - does that mean a moving object over the sea > 300' should be NOTAMd?
A curious thought isnt it - how can we pilots ensure our safety if we have not been presented with all the information we need...Id love for someone at the CAA to comment about the consideration of moving object hazards whilst engaged in overwater flight...
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With a rad alt, one needs to know the terrain over which one is going to use it. That is why many aerodromes where precision approaches are provided produce a precision approach terrain chart which allows one to check the relative elevation of the terrain under the approach close to the runway and base any rad alt minima on that.
Over the sea depending on the type of rad alt system there can be some error caused by the movement of the waves and doppler effect.
When it comes to obstacles, all obstacles within the FIR whuch are 100m or more above the surface are required to be included in the AIP ENR 5.4 That includes mobile obstacles.
Any obstacle (including a mobile one) not included in the AIP is NOTAMed and there are a few each year where rigs are known to be moving about the place.
However and perhaps the more maritime among us can comment on this - beyond the 3nm mile limit? (from the coast) as far a vessels are concerned they are on the "high seas" and don't have to tell anyone who they are where they are or what they are up to. This would seem to make it difficult to determine exactly where those obstacles are.
Of course one could be letting down in the middle of the channel and pop out head on to a small naval boat launching a missile at what it sees as a hostile attack!
Taking that last unfortunate point perhaps when "bending the rules" these days we should think of the (unexpected) wider implications. e.g. why does that guy pop out of cloud low over the sea when he could make a normal approach at xyz - might be up to no good!
Regards,
DFC
Over the sea depending on the type of rad alt system there can be some error caused by the movement of the waves and doppler effect.
When it comes to obstacles, all obstacles within the FIR whuch are 100m or more above the surface are required to be included in the AIP ENR 5.4 That includes mobile obstacles.
Any obstacle (including a mobile one) not included in the AIP is NOTAMed and there are a few each year where rigs are known to be moving about the place.
However and perhaps the more maritime among us can comment on this - beyond the 3nm mile limit? (from the coast) as far a vessels are concerned they are on the "high seas" and don't have to tell anyone who they are where they are or what they are up to. This would seem to make it difficult to determine exactly where those obstacles are.
Of course one could be letting down in the middle of the channel and pop out head on to a small naval boat launching a missile at what it sees as a hostile attack!
Taking that last unfortunate point perhaps when "bending the rules" these days we should think of the (unexpected) wider implications. e.g. why does that guy pop out of cloud low over the sea when he could make a normal approach at xyz - might be up to no good!
Regards,
DFC
Last edited by DFC; 27th Jul 2005 at 10:12.
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FF
The AIP is not the law. Only the ANO is the law (in this context).
Also, phrases like "first obtain an accurate fix" are a give-away that this is an informal piece. What is an "accurate" fix??
If you have enough time to thumb through every piece of paper that's ever emanated from the CAA (AIP, AIC, all the wonderful differently coloured supplements like Pink and Mauve) you can find just about anything. You will find something that makes GPS illegal, if you look hard enough.
Incidentally, a radar altimeter does look slightly foward.
The AIP is not the law. Only the ANO is the law (in this context).
Also, phrases like "first obtain an accurate fix" are a give-away that this is an informal piece. What is an "accurate" fix??
If you have enough time to thumb through every piece of paper that's ever emanated from the CAA (AIP, AIC, all the wonderful differently coloured supplements like Pink and Mauve) you can find just about anything. You will find something that makes GPS illegal, if you look hard enough.
Incidentally, a radar altimeter does look slightly foward.
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I didnt say it was the law...only that it was the authorities word on the matter. There is much in the AIP which is not encapsulated in the ANO yet we comply with it. But thats not the point.
Consider this..Given the statement in the UK AIP, following an accident of any description where the pilot did not follow this 'advice' or whatever you wish to call it - what would you expect a court decision to come up with - personally I wouldnt like to call it - it could go either way.
In all cases unless the person in question was in receipt of a radar service Im sure his airmanship would be called into question...and whilst he might not have broken any law would you (given the advice from the authorities) possibly consider his actions to be reckless or negligent given that such advice was for a completely different set of actions? Would you have considered that the commander had placed his aircraft in danger?
If so then you have broken laws...(re articles of the ANO about such actions)
Consider this..Given the statement in the UK AIP, following an accident of any description where the pilot did not follow this 'advice' or whatever you wish to call it - what would you expect a court decision to come up with - personally I wouldnt like to call it - it could go either way.
In all cases unless the person in question was in receipt of a radar service Im sure his airmanship would be called into question...and whilst he might not have broken any law would you (given the advice from the authorities) possibly consider his actions to be reckless or negligent given that such advice was for a completely different set of actions? Would you have considered that the commander had placed his aircraft in danger?
If so then you have broken laws...(re articles of the ANO about such actions)
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These threads just run and run. Luckily, there isn't much data on what happens in bodged DIY IAPs.
Graham Hill was one, apparently. That one went badly wrong in the courts; I gather from an old timer who was familiar with the case that his IMCR had expired. Is the report online anywhere? That would put it clearly "out". But in those days a lot of planes, including airliners, were flying into terrain. Today, there is no excuse because even the cheapest GPS tells you where you are exactly, some 99.99% of the time.
In the absence of licensing/airworthiness issues, insurance will pay out in a case of negligence. That's covered by insurance. Not much use to the pilot because a bodged IAP (DIY or official) is likely to result in a CFIT and they are usually fatal. But it could affect whether passenger claims exhaust the 3P cover and hit the pilot's estate.
Not always fatal though; I know of one where he survived and there wasn't any legal drama. He did a GPS based IAP with no supporting position fix, among terrain. But what got him was not the descent, it was the lack of a missed approach procedure.
So, what seems to matter in these things is not CAA action (especially as the pilot is likely to be dead) but insurance issues. And insurance does cover negligence - up to the numerical limit of the cover.
All in all, not enough to go on and just as well!
IFR, one has to stay at the MSA unless landing and then how low can one go? I would do 700ft AGL over fairly flat country, with a position fix via two independent methods, plus current QNH and altimeter verified (for gross error) against an IFR GPS. Or 500ft over the sea. Otherwise, a low level letdown (radar based, obviously). The trouble is that a low level letdown is that they will take you down only to 1000ft AGL anyway. All that does is that it supposedly eliminates obstacles that you didn't spot on the chart, but you are trusting the ATCO completely for terrain clearance because he is giving you vectors and expects you to fly them.
More important, IMV, is to establish the cloudbase in the area. If a nearby unit gives it as OVC003 there is no point in trying anything. Perhaps a really experienced ex-mil low flyer could do OVC003 over water, to land on a runway which is right on the coast. If the whole area is around BKN010 and it is fairly flat, that should be perfectly safe for a DIY descent using a double position fix, and this is over the sea also.
Just my 2p. You have a point but the CAA are just AN authority on what is safe, not the final authority. Given no FDR/CVR one usually cannot establish what really happened anyway. They couldn't prosecute a dead pilot; they could offer an opinion in an insurance argument. A lot of what the CAA have written (for GA consumption) is bunk, especially on slightly modern things like GPS. There is so much stuff that is uselessly vague (or implies that it overrides manufacturer's guidelines) that a lawyer would have a field day with it.
Graham Hill was one, apparently. That one went badly wrong in the courts; I gather from an old timer who was familiar with the case that his IMCR had expired. Is the report online anywhere? That would put it clearly "out". But in those days a lot of planes, including airliners, were flying into terrain. Today, there is no excuse because even the cheapest GPS tells you where you are exactly, some 99.99% of the time.
In the absence of licensing/airworthiness issues, insurance will pay out in a case of negligence. That's covered by insurance. Not much use to the pilot because a bodged IAP (DIY or official) is likely to result in a CFIT and they are usually fatal. But it could affect whether passenger claims exhaust the 3P cover and hit the pilot's estate.
Not always fatal though; I know of one where he survived and there wasn't any legal drama. He did a GPS based IAP with no supporting position fix, among terrain. But what got him was not the descent, it was the lack of a missed approach procedure.
So, what seems to matter in these things is not CAA action (especially as the pilot is likely to be dead) but insurance issues. And insurance does cover negligence - up to the numerical limit of the cover.
All in all, not enough to go on and just as well!
IFR, one has to stay at the MSA unless landing and then how low can one go? I would do 700ft AGL over fairly flat country, with a position fix via two independent methods, plus current QNH and altimeter verified (for gross error) against an IFR GPS. Or 500ft over the sea. Otherwise, a low level letdown (radar based, obviously). The trouble is that a low level letdown is that they will take you down only to 1000ft AGL anyway. All that does is that it supposedly eliminates obstacles that you didn't spot on the chart, but you are trusting the ATCO completely for terrain clearance because he is giving you vectors and expects you to fly them.
More important, IMV, is to establish the cloudbase in the area. If a nearby unit gives it as OVC003 there is no point in trying anything. Perhaps a really experienced ex-mil low flyer could do OVC003 over water, to land on a runway which is right on the coast. If the whole area is around BKN010 and it is fairly flat, that should be perfectly safe for a DIY descent using a double position fix, and this is over the sea also.
Just my 2p. You have a point but the CAA are just AN authority on what is safe, not the final authority. Given no FDR/CVR one usually cannot establish what really happened anyway. They couldn't prosecute a dead pilot; they could offer an opinion in an insurance argument. A lot of what the CAA have written (for GA consumption) is bunk, especially on slightly modern things like GPS. There is so much stuff that is uselessly vague (or implies that it overrides manufacturer's guidelines) that a lawyer would have a field day with it.
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Luckily, there isn't much data on what happens in bodged DIY IAPs
http://www.aaiu.ie/AAIUviewitem.asp?...g=ENG&loc=1280
Summary;
G-HAUG departed Belfast International - Aldergrove Airport on 12 December at 18.03 hrs, to return to its home base at Ballyedmond, Co. Down, Northern Ireland. This would normally be a flight of some 20 minutes duration. The approach to the home base was executed using a locally produced GPS-based approach procedure. Having commenced its descent, in preparation for landing at Ballyedmond, the helicopter struck the north face of the Carlingford Mountains at 960 feet above sea level, approximately 2 miles SE of the village of Omeath, Co. Louth, at 18.16 hrs. All three occupants suffered fatal injuries.
Who wants lots of that type of data?
Regards,
DFC
http://www.aaiu.ie/AAIUviewitem.asp?...g=ENG&loc=1280
Summary;
G-HAUG departed Belfast International - Aldergrove Airport on 12 December at 18.03 hrs, to return to its home base at Ballyedmond, Co. Down, Northern Ireland. This would normally be a flight of some 20 minutes duration. The approach to the home base was executed using a locally produced GPS-based approach procedure. Having commenced its descent, in preparation for landing at Ballyedmond, the helicopter struck the north face of the Carlingford Mountains at 960 feet above sea level, approximately 2 miles SE of the village of Omeath, Co. Louth, at 18.16 hrs. All three occupants suffered fatal injuries.
Who wants lots of that type of data?
Regards,
DFC