Descending through cloud without a procedure
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DFC, I give up. A 30deg NDB error is 1-2 miles off track.
Anyway, such errors, caused by terrain contours and/or coastal effects, are common knowledge to pilots who fly these approaches for real.
Anyway, such errors, caused by terrain contours and/or coastal effects, are common knowledge to pilots who fly these approaches for real.
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IO540 - oh no dont do that, dont take the bait. I have already got that sinking feeling. 
Here is the question though. EGKA - you have to land, some "unexpected" emergency, the base is 400 feet - below minima and for same unexplained reason you can use either the GPS or NDB / DME but not both. Which one would you prefer?
Dont know if you read Flying - there was a good article on the paperless cockpit and the circumstances in which the writer held the view the FAA would be happy if "you left the paper maps at home". I cant remember if it was just his view or he had got an official pronouncement from the FAA. I wil try and dig out the article.
Here is the question though. EGKA - you have to land, some "unexpected" emergency, the base is 400 feet - below minima and for same unexplained reason you can use either the GPS or NDB / DME but not both. Which one would you prefer?
Dont know if you read Flying - there was a good article on the paperless cockpit and the circumstances in which the writer held the view the FAA would be happy if "you left the paper maps at home". I cant remember if it was just his view or he had got an official pronouncement from the FAA. I wil try and dig out the article.
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Mandatory
I've read all the posts carefully and wonder at why so many are so keen to venture into the legal world of so many things when i doubt whether the lawyers amongst us would be willing to define an absolute in all of this at all.
Class 1 VHF navigation radio is tested for many standards, FM immune protection being just one.
Class 3 equipment is usable at all times unless it is stipulated that the use of such equipment is MANDATORY!
Currently it is only within certain controlled airspace that, for a particular purpose, the use of the equipment is stipulated to be mandatory.
It is not stipulated to be neccesary anywhere outside of controlled airspace. I have noted a number of personal interpretations of the JARs. There has been some qualified advice that the use of Class 3 equipment outside of controlled airspace (class G) when undertaking an ILS in IMC is illegal. The arguement here is that because you cannot do an ILS without using the ILS receiver equipment then it must be mandatory equipment. That is not neccessarily the correct us of 'mandatory'. The word mandatory leads to the action that must be followed following the issue of a mandate. No such mandate has been issued to date with regard to the use of class 3 equipment outside contolled airspace.
Class 3 equipment must as with Class 1 be tested and signed off as being within limits and FIT for its purpose and therefore must be complient with the JARs. Or, do we have a double standard!
Class 1 VHF navigation radio is tested for many standards, FM immune protection being just one.
Class 3 equipment is usable at all times unless it is stipulated that the use of such equipment is MANDATORY!
Currently it is only within certain controlled airspace that, for a particular purpose, the use of the equipment is stipulated to be mandatory.
It is not stipulated to be neccesary anywhere outside of controlled airspace. I have noted a number of personal interpretations of the JARs. There has been some qualified advice that the use of Class 3 equipment outside of controlled airspace (class G) when undertaking an ILS in IMC is illegal. The arguement here is that because you cannot do an ILS without using the ILS receiver equipment then it must be mandatory equipment. That is not neccessarily the correct us of 'mandatory'. The word mandatory leads to the action that must be followed following the issue of a mandate. No such mandate has been issued to date with regard to the use of class 3 equipment outside contolled airspace.
Class 3 equipment must as with Class 1 be tested and signed off as being within limits and FIT for its purpose and therefore must be complient with the JARs. Or, do we have a double standard!
Last edited by homeguard; 22nd May 2006 at 17:03. Reason: incorrect fact
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Fuji
In an OVC004 I would divert to some place with an ILS and a low enough DH e.g. Bournemouth (from memory). In an emergency (below minima for even an ILS) I would pick any ILS with no high terrain nearby, which is most ILS runways in the south.
But if I had to get into Shoreham under OVC004 (can't see why in reality) I would fly the existing 20 or 02 NDB/DME procedure, as depicted in my GPS database, using the GPS. Much more accurate.
Regards paper charts, I don't think there could be a serious debate as to the legality of flying without them. It's always been legal (Part 91, or UK private flight context). One can debate the wisdom indefinitely, like most things in this business
IMHO getting the FAA to say it is OK to fly without paper charts (if you carry them in some electronic form) is a bit like getting the CAA to say GPS isn't illegal.
I do get Flying, a good mag, but don't recall reading about this.
Homeguard
I too think that there has to be more to this than "can't fly an ILS in IMC if not FM immune". So many flying school planes, and most rental planes, are not FM immune and the CAA would have done a few people by now. They've had a number of years to get around to it. I know it's said that IMC Rating training can be done in VMC but all the smarter instructors do at least some in IMC - as indeed they should.
In an OVC004 I would divert to some place with an ILS and a low enough DH e.g. Bournemouth (from memory). In an emergency (below minima for even an ILS) I would pick any ILS with no high terrain nearby, which is most ILS runways in the south.
But if I had to get into Shoreham under OVC004 (can't see why in reality) I would fly the existing 20 or 02 NDB/DME procedure, as depicted in my GPS database, using the GPS. Much more accurate.
Regards paper charts, I don't think there could be a serious debate as to the legality of flying without them. It's always been legal (Part 91, or UK private flight context). One can debate the wisdom indefinitely, like most things in this business
IMHO getting the FAA to say it is OK to fly without paper charts (if you carry them in some electronic form) is a bit like getting the CAA to say GPS isn't illegal.I do get Flying, a good mag, but don't recall reading about this.
Homeguard
I too think that there has to be more to this than "can't fly an ILS in IMC if not FM immune". So many flying school planes, and most rental planes, are not FM immune and the CAA would have done a few people by now. They've had a number of years to get around to it. I know it's said that IMC Rating training can be done in VMC but all the smarter instructors do at least some in IMC - as indeed they should.
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A non-FM immune ILS or VOR system is U/S. Put another way, it no longer meets the required standard for it to be used as intended.It is not sensible or legal to use U/S equipment as a sole source of navigation information on an IFR flight.
The FAA say that you no longer need to carry paper charts in a suitably equipped aeroplane (G1000 etc....). I did have a reference but can't find it at the moment, so don't ask me for it
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"In an OVC004 I would divert to some place with an ILS" of course.
That was why it was hypothetical. My point was that I as you would far rather fly the gps than the NDB / DME. Simply a follow up to the earlier point.
"The FAA say that you no longer need to carry paper charts in a suitably equipped aeroplane (G1000 etc....). I did have a reference but can't find it at the moment, so don't ask me for it"
Yes that was what I thought - they had specifically sanctioned it.
"Can you rely on a non-FM immune VOR? - NO.
Why, because it is legally U/S."
Reference please. For flights under IFR the requirement is one FM immune VOR WITHIN controlled airspace. Where does the legislation specify an FM immune VOR is required OUTSIDE controlled airspace or for that matter where does the legislation state in these circumstances the receiver is u/s?
I would also be interested in the specific reference to the G/S FM immune requirement for approaches outside controlled airspace.
I gather the CAA have not yet completed their report on the FM interference risk, however whilst theoretically it exists I dont think there has yet been a single reported case of FM interference.
That was why it was hypothetical. My point was that I as you would far rather fly the gps than the NDB / DME. Simply a follow up to the earlier point.
"The FAA say that you no longer need to carry paper charts in a suitably equipped aeroplane (G1000 etc....). I did have a reference but can't find it at the moment, so don't ask me for it"
Yes that was what I thought - they had specifically sanctioned it.
"Can you rely on a non-FM immune VOR? - NO.
Why, because it is legally U/S."
Reference please. For flights under IFR the requirement is one FM immune VOR WITHIN controlled airspace. Where does the legislation specify an FM immune VOR is required OUTSIDE controlled airspace or for that matter where does the legislation state in these circumstances the receiver is u/s?
I would also be interested in the specific reference to the G/S FM immune requirement for approaches outside controlled airspace.
I gather the CAA have not yet completed their report on the FM interference risk, however whilst theoretically it exists I dont think there has yet been a single reported case of FM interference.
Last edited by Fuji Abound; 22nd May 2006 at 21:45.
Hi Fuji
I'm not sure what you mean by this; if you want to see a reference to ILS approaches outside controlled airspace, I have given one back on page 2 although it's up to each of us to decide on its relevance.
If you specifically mean a reference to the FM Immunity (or lack thereof) of glideslope receivers, then I suspect you'll never find one. Glideslopes work on UHF and therefore are not susceptible to FM interference. It is the VHF localiser which is, if only in theory.
Hello Homeguard
It's interesting that you mention the LA Class 1 and Class 3 approvals. I spoke with an engineer I know last year and had been led to believe, perhaps wrongly, that these classifications of kit can be somewhat bogus under the JAR/EASA schema. Perhaps I had misunderstood what he was saying.
This page and this one both hint that these definitions might not be entirely relevant to aircraft issued with CofA's by EASA, for example. Specifically, from the former page;
Needless to say that most club/school spam-cans are indeed covered by EC1592/2002. Permit aircraft and some older rarities are not.
From the second source;
If the CAA themselves are suggesting that their own requirements have been 'superceded', is it not possible that this may have occurred in the ORS that states avionics equipment must be FM Immune (i.e. equivalent to LA Class I) in order to fly an ILS approach inside or outside controlled airspace?
I ask this as a genuine question. If the Class I/Class III distinctions are still valid and meaningful for all UK registered aircraft then fair play. But if they are only meaningful for those aicraft still maintained under national airworthiness rules (as opposed to JAA/EASA) then it muddies the water a bit.
All a bit of a mess really.
Originally Posted by Fuji Abound
I would also be interested in the specific reference to the G/S FM immune requirement for approaches outside controlled airspace.
If you specifically mean a reference to the FM Immunity (or lack thereof) of glideslope receivers, then I suspect you'll never find one. Glideslopes work on UHF and therefore are not susceptible to FM interference. It is the VHF localiser which is, if only in theory.
Hello Homeguard
It's interesting that you mention the LA Class 1 and Class 3 approvals. I spoke with an engineer I know last year and had been led to believe, perhaps wrongly, that these classifications of kit can be somewhat bogus under the JAR/EASA schema. Perhaps I had misunderstood what he was saying.
This page and this one both hint that these definitions might not be entirely relevant to aircraft issued with CofA's by EASA, for example. Specifically, from the former page;
With effect from 28 September 2003, for the purposes of new certifications [of avionics equipment], BCAR Section R is applicable as a requirement only to those aircraft which are excluded from the coverage of Regulation (EC) No. 1592/2002. For a definition of these aircraft, see CAP 455 Airworthiness Notice No. 1.
From the second source;
Volumes 1 and 2 of CAP 208 - Aircraft Radio Equipment, are now considered to be obsolescent in that these volumes no longer represent current minimum performance requirements or complete and definitive records of aircraft radio equipment approved by CAA. Volume 1 of CAP 208, listed certain ICAO standards (for example, ICAO annex 10 requires VHF communication transceivers to have a frequency stability operation of plus or minus 0.003%), whcih have been superseded by later requirements.
I ask this as a genuine question. If the Class I/Class III distinctions are still valid and meaningful for all UK registered aircraft then fair play. But if they are only meaningful for those aicraft still maintained under national airworthiness rules (as opposed to JAA/EASA) then it muddies the water a bit.
All a bit of a mess really.
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ICAO Annex 10 is the reference and it applies worldwide.
The FAA may not have such a requirement at the moment within the CONUS because they may have restricted the FM spectrum to avoid the problem. However, FAA aircraft operating outside the US are required to conform to the requirments.
The GS being UHF is not affected.
What are you saying Fuji? using the GS without a LOC?
Everyone is still getting confused by the requirements to carry certain equipment to operate within certain airspace (it has to be fitted, and serviceable. It does not have to be turned on unless being used!) and a totally separate requirement to have a serviceable VOR or ILS equipment in order to use VOR or ILS information.
Ask anyone if they will try to fly an ILS with equipment that is placared as "U/S" or even "unreliable". I can guarantee that no sensible pilot will use such equipment in IMC.
Ask an avionics engineer to certify a non-FM immune instalation as fit for making ILS approaches and you will get a prompt no!
I feel it is only time before we have someone trying to fly using GS on nav 1 and the NDB to somewhere like Blackpool.
Accidents waiting to happen is the term I believe.
Regards,
DFC
PS: No explanation of the set-up you use for the GPS yet IO540?
"A 30deg NDB error is 1-2 miles off track" is bo
ox
The FAA may not have such a requirement at the moment within the CONUS because they may have restricted the FM spectrum to avoid the problem. However, FAA aircraft operating outside the US are required to conform to the requirments.
The GS being UHF is not affected.
What are you saying Fuji? using the GS without a LOC?
Everyone is still getting confused by the requirements to carry certain equipment to operate within certain airspace (it has to be fitted, and serviceable. It does not have to be turned on unless being used!) and a totally separate requirement to have a serviceable VOR or ILS equipment in order to use VOR or ILS information.
Ask anyone if they will try to fly an ILS with equipment that is placared as "U/S" or even "unreliable". I can guarantee that no sensible pilot will use such equipment in IMC.
Ask an avionics engineer to certify a non-FM immune instalation as fit for making ILS approaches and you will get a prompt no!
I feel it is only time before we have someone trying to fly using GS on nav 1 and the NDB to somewhere like Blackpool.
Accidents waiting to happen is the term I believe.Regards,
DFC
PS: No explanation of the set-up you use for the GPS yet IO540?
"A 30deg NDB error is 1-2 miles off track" is bo
ox
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Charley - I share your views and should have read your earlier post properly. I would agree it is a requirment the G/S must be FM immune whether in or outside controlled airspace. I think I am corect that the VOR is only "required" to be FM immune within controlled airspace. Presumably, subject to the afore, there is no issue with the schools etc operating IFR outside controlled airspace and engaging on all forms of approach except an ILS.
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Fuji,
To put it in very very very simple terms for you;
In ceratin classes of airspace your aircraft needs to be equipped with certain serviceable equipment.
In class G there is no requirment for the aircraft to have a serviceable VOR even when flying IFR in IMC.
That means that you can fly an aircraft with a VOR that has 60 to 80 degree errors perfectly happy in class G provided that you do not rely on the accuracy of the VOR to ensure separation from terrain, controlled airspace or other aircraft.
Do you now understand the difference between a requirement to have equipment fitted and the requirement for equipment to be serviceable before using it?
I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT".
It is a commonsense safety issue!
Regards,
DFC
PS: Reputable schools do not rely on non-FM immune equipment.
To put it in very very very simple terms for you;
In ceratin classes of airspace your aircraft needs to be equipped with certain serviceable equipment.
In class G there is no requirment for the aircraft to have a serviceable VOR even when flying IFR in IMC.
That means that you can fly an aircraft with a VOR that has 60 to 80 degree errors perfectly happy in class G provided that you do not rely on the accuracy of the VOR to ensure separation from terrain, controlled airspace or other aircraft.
Do you now understand the difference between a requirement to have equipment fitted and the requirement for equipment to be serviceable before using it?
I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT".
It is a commonsense safety issue!
Regards,
DFC
PS: Reputable schools do not rely on non-FM immune equipment.
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DFC
I wanted to clarrify Charley's interpretation which I guess you have done.
The position would seem to be you are not required to have an FM immune VOR outside controlled airspace to operate IFR.
My understanding is that the VOR has to be placarded "not FM immune". I know of many aircraft with this wording so I assume the avionics chaps know what they are doing. The placard does not say the equipment is unserviceable. In exactly the same way the comms boxes may not be FM immune, but in that case there is a specific exemption permitting their use in controlled airspace. In my opinion your comments are therefore misleading becasue you are legally entitled to use the VOR other wise the legislation would be worded in the way it is for the G/S. An all together different debate is whether you should rely on a non FM immune VOR as the sole means of navigation. I guess their are many aircraft with the G/S FM immune but not the second nav box for example. Equally there are those perhaps with neither FM immune but with a GPS. Perhaps again there are those that understand how to fly a DME arc.
I wanted to clarrify Charley's interpretation which I guess you have done.
The position would seem to be you are not required to have an FM immune VOR outside controlled airspace to operate IFR.
My understanding is that the VOR has to be placarded "not FM immune". I know of many aircraft with this wording so I assume the avionics chaps know what they are doing. The placard does not say the equipment is unserviceable. In exactly the same way the comms boxes may not be FM immune, but in that case there is a specific exemption permitting their use in controlled airspace. In my opinion your comments are therefore misleading becasue you are legally entitled to use the VOR other wise the legislation would be worded in the way it is for the G/S. An all together different debate is whether you should rely on a non FM immune VOR as the sole means of navigation. I guess their are many aircraft with the G/S FM immune but not the second nav box for example. Equally there are those perhaps with neither FM immune but with a GPS. Perhaps again there are those that understand how to fly a DME arc.
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That means that you can fly an aircraft with a VOR that has 60 to 80 degree errors perfectly happy in class G provided that you do not rely on the accuracy of the VOR to ensure separation from terrain, controlled airspace or other aircraft.
Do you now understand the difference between a requirement to have equipment fitted and the requirement for equipment to be serviceable before using it?
I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT".
Do you now understand the difference between a requirement to have equipment fitted and the requirement for equipment to be serviceable before using it?
I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT".
So we may as well rip out all our Nav gear and bung it in the bin according to you.
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I think that those who advocate relying on ILS and VOR non-FM immune systems in class G are saying the aviation equivalent of "driving a car with defective brakes is OK if it has an MOT.
Well the CAA obviously think it is OK so far as the VOR is concerned. I guess they could have just as easily required FM immunity in class G for the VOR as they did for the G/S. The fact remains they did not. I wonder why?
Well the CAA obviously think it is OK so far as the VOR is concerned. I guess they could have just as easily required FM immunity in class G for the VOR as they did for the G/S. The fact remains they did not. I wonder why?
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ILS (LOC actually) frequencies are lower down the VHF scale, thus nearer to the FM broadcast band?
Still, nobody I have ever met has ever known of a case of actual interference. For all the grief and expense this has caused... how long has ILS and VOR been about, how long has the FM broadcast band been about? You would think that if there were any problems it would have been glaringly obvious by now. We are talking about 2-3 decades in which to demonstrate a problem.
Still, nobody I have ever met has ever known of a case of actual interference. For all the grief and expense this has caused... how long has ILS and VOR been about, how long has the FM broadcast band been about? You would think that if there were any problems it would have been glaringly obvious by now. We are talking about 2-3 decades in which to demonstrate a problem.
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"We are talking about 2-3 decades in which to demonstrate a problem."
Correct. 1979 was the year in which it was agreed the 105 to 106 Mhz part of the band could be used by commercial radio stations from which the "fear" derives of possible interference. As I stated previously I understand there has not been a single reported case of such interference but the theoretical possibility exists. I am not sure how many stations actually use this part of the spectrum anyway but this gives a flavour http://www.electricbluesclub.co.uk/u..._stations.html
Interesting that the whole of the USAF AWACS fleet was operating "with defective brakes" (non FM immune) until 1999 under certificates of exemption and only then ceased to do so becasue the EU refused to issue any more certificates.
Correct. 1979 was the year in which it was agreed the 105 to 106 Mhz part of the band could be used by commercial radio stations from which the "fear" derives of possible interference. As I stated previously I understand there has not been a single reported case of such interference but the theoretical possibility exists. I am not sure how many stations actually use this part of the spectrum anyway but this gives a flavour http://www.electricbluesclub.co.uk/u..._stations.html
Interesting that the whole of the USAF AWACS fleet was operating "with defective brakes" (non FM immune) until 1999 under certificates of exemption and only then ceased to do so becasue the EU refused to issue any more certificates.
Last edited by Fuji Abound; 23rd May 2006 at 20:45.
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No. The agreement made was that from about 1997, the FM band would be expanded. The reason for giving away the protection was that it was expected that technology such as MLS would remove the requirement for ILS.
Unfortunately, technology did not go as expected and the solution was to require instalation of filters on current technology equipment.
------------
Englishal,
So we may as well rip out all our Nav gear and bung it in the bin according to you
No you could have a cheap easy to install filter fitted and then your equipment would be FM immune.
--------
Fuji/IO540,
Just because the CAA does not require certain equipment to be carried and be serviceable in Class G airspace it does not not not mean that they are saying it is OK to rely on equipment that does not meet the required standard.
The CAA does not set any standard for some required items in aircraft. Do you think that you could safely claim that the elastoplast stuffed into the seat pocket is the first aid kit.......or that the bottle you peed in was the fire extinguisher?
If the DME was labled as "unreliable" could you use it to complete an approach in IMC? NO. and that goes for FAA/CAA/JAA or any other authority. For not FM immune read unreliable. No mention of airspace there!
Of course ther will always be the idiots who fly with U/S equipment and rely on unreliable fuel gauges among other things.
Regards,
DFC
Unfortunately, technology did not go as expected and the solution was to require instalation of filters on current technology equipment.
------------
Englishal,
So we may as well rip out all our Nav gear and bung it in the bin according to you
No you could have a cheap easy to install filter fitted and then your equipment would be FM immune.
--------
Fuji/IO540,
Just because the CAA does not require certain equipment to be carried and be serviceable in Class G airspace it does not not not mean that they are saying it is OK to rely on equipment that does not meet the required standard.
The CAA does not set any standard for some required items in aircraft. Do you think that you could safely claim that the elastoplast stuffed into the seat pocket is the first aid kit.......or that the bottle you peed in was the fire extinguisher?
If the DME was labled as "unreliable" could you use it to complete an approach in IMC? NO. and that goes for FAA/CAA/JAA or any other authority. For not FM immune read unreliable. No mention of airspace there!
Of course ther will always be the idiots who fly with U/S equipment and rely on unreliable fuel gauges among other things.
Regards,
DFC
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GASIL 1/2001 - "as a result of the 1979 world radio conference the decision was taken to allow FM broadcasters to use the 105 to 108 Mhz .. .."
http://www.wws.princeton.edu/ota/disk3/1982/8221/822104.PDF#search='world%20radio%20conference%201979'
I wonder why the CAA granted exemption certificates until 1999 - 20 years after FM broadcasters were permitted to use these bands? Were these certificates the work of idiots or did the CAA have reasonable grounds for their grant? What has changed since 1999? Why did the CAA not prohibit the use of non FM immune VORs? They were clearly capable of prohibiting the use of non FM immune loc.
I suspect the real reason is the CAA and other national organisations within Europe realised there was a very small but never the less real risk FM broadcasts could make the integrity of loc unsafe which in itself presented a serious safety hazard whether in controlled or uncontrolled air space for obvious reasons. Never the less they felt the risk sufficiently small to grant the exemptions that were given (or maybe they gave in to the political pressure) or maybe they realised that the USAF would not be relying solely on loc approaches. They also realised that outside controlled airspace given the widespread use of other means of cross checking position it remained "safe" to use non FM immune VORs.
I would be interested to know the effects of FM interference. What would be the indicative signs. Would a half competent pilot have ample warning that all was not well. Would he in any event be cross checking his VOR with GPS, NDBs, DME, radar, dead reckoning. I would have thought so. If tracking two VORs would both be effected at the same time - I would have thought not. I find it hard to imagine that a pilot would not see some warnigns signs that all was not well and have plenty of time to resolve the issue.
I am not advocating flying with non FM immune equipment. The fact remains that there are many aircraft without, including those used for IMC training. Are they operating illegally or irresponsibly? I am far from convinced they are.
http://www.wws.princeton.edu/ota/disk3/1982/8221/822104.PDF#search='world%20radio%20conference%201979'
I wonder why the CAA granted exemption certificates until 1999 - 20 years after FM broadcasters were permitted to use these bands? Were these certificates the work of idiots or did the CAA have reasonable grounds for their grant? What has changed since 1999? Why did the CAA not prohibit the use of non FM immune VORs? They were clearly capable of prohibiting the use of non FM immune loc.
I suspect the real reason is the CAA and other national organisations within Europe realised there was a very small but never the less real risk FM broadcasts could make the integrity of loc unsafe which in itself presented a serious safety hazard whether in controlled or uncontrolled air space for obvious reasons. Never the less they felt the risk sufficiently small to grant the exemptions that were given (or maybe they gave in to the political pressure) or maybe they realised that the USAF would not be relying solely on loc approaches. They also realised that outside controlled airspace given the widespread use of other means of cross checking position it remained "safe" to use non FM immune VORs.
I would be interested to know the effects of FM interference. What would be the indicative signs. Would a half competent pilot have ample warning that all was not well. Would he in any event be cross checking his VOR with GPS, NDBs, DME, radar, dead reckoning. I would have thought so. If tracking two VORs would both be effected at the same time - I would have thought not. I find it hard to imagine that a pilot would not see some warnigns signs that all was not well and have plenty of time to resolve the issue.
I am not advocating flying with non FM immune equipment. The fact remains that there are many aircraft without, including those used for IMC training. Are they operating illegally or irresponsibly? I am far from convinced they are.
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No you could have a cheap easy to install filter fitted and then your equipment would be FM immune.
If the DME was labled as "unreliable" could you use it to complete an approach in IMC? NO.
The only time I have seen glideslope distortion was when a 767 taxyed across the threshold of a runway which I was approaching on the ILS. It was quite a marked distortion.
Anyway, all this is academic. In a few years we'll be able to buy one box of tricks (called a GPS) which will do for DME, position fixing, precision approaches and NPA's.........at least I hope so
Join Date: Mar 2002
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Fuji,
Perhaps I did not make myself clear.
The agreement in 1979 regarding the expansion of the FM band and the increase in radiated power did not have immediate effect. The expansion was planned to start in the late 1990s.
That is why between 1979 and the late 1990's there was no problem with non-FM immune equipment - the problem was not yet there.
The 20 year lead time was to allow technology that was to replace ILS etc to be developed. That technology did not happen for various reasons and we ended up in the position of not having suitable technology but having already promissed to give away the spectrum.
The solution was simply fitting filters to existing equipment.
You will find that technology developed in the 1990's is FM immune because the designers had to meet the requierd specs which included FM immunity.
Remember that radio stations are licensed. The authorities can base FM immunity requriements at any particular time on what FM stations are licensed and the conditions of those licenses.
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Englishal,
Ask your friendly avionics engineer for info.
A chat with the following company who have an approved filter will also help you;
http://www.chelton.co.uk/
Regards,
DFC
If people had paid attention to what was going on and simply put £1 per flight hour aside since 1979, the average spam can could have dual GNS430 or similar with the cost of instalation paid for and some money left for updates!
Ok so not many here remember back that far but the aircraft they fly do!
Perhaps I did not make myself clear.
The agreement in 1979 regarding the expansion of the FM band and the increase in radiated power did not have immediate effect. The expansion was planned to start in the late 1990s.
That is why between 1979 and the late 1990's there was no problem with non-FM immune equipment - the problem was not yet there.
The 20 year lead time was to allow technology that was to replace ILS etc to be developed. That technology did not happen for various reasons and we ended up in the position of not having suitable technology but having already promissed to give away the spectrum.
The solution was simply fitting filters to existing equipment.
You will find that technology developed in the 1990's is FM immune because the designers had to meet the requierd specs which included FM immunity.
Remember that radio stations are licensed. The authorities can base FM immunity requriements at any particular time on what FM stations are licensed and the conditions of those licenses.
------------
Englishal,
Ask your friendly avionics engineer for info.
A chat with the following company who have an approved filter will also help you;
http://www.chelton.co.uk/
Regards,
DFC
If people had paid attention to what was going on and simply put £1 per flight hour aside since 1979, the average spam can could have dual GNS430 or similar with the cost of instalation paid for and some money left for updates!
Ok so not many here remember back that far but the aircraft they fly do!