FM immunity - thoroughly confused by Pilot magazine
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FM immunity - thoroughly confused by Pilot magazine
'Pilot' Magazine had an article on avionics this month which unequivocally stated:
This had me worried, as I was doing just that last week (IFR in IMC under the edge of the Birmingham TMA, for example), so I looked it up.
Unless I've read it wrong, only the equipment required by the ANO (Section 1 Schedule 5) has to be FM Immune, and any other equipment you may carry or choose to use is up to you? As I understand it therefore:
IFR in CAS: must have radio, transponder, ADF, DME and VOR*
VFR in CAS: must have radio
Landing in CAS: must have ILS* if airspace notified as requiring it
i.e. the ones marked * must be FM immune and only under those circumstances. And I remember a training flight where we flew through the Lyneham CTA IFR tracking CPT on a non-immune set: yes, we were in VMC, but we definitely got an IFR clearance...
Am I missing something, or was the article in 'Pilot' misleading?
Tim
If you fly with non FM Immune equipment in class A, B, or C airspace, or under IFR/IMC conditions, you are breaking the law.
Unless I've read it wrong, only the equipment required by the ANO (Section 1 Schedule 5) has to be FM Immune, and any other equipment you may carry or choose to use is up to you? As I understand it therefore:
IFR in CAS: must have radio, transponder, ADF, DME and VOR*
VFR in CAS: must have radio
Landing in CAS: must have ILS* if airspace notified as requiring it
i.e. the ones marked * must be FM immune and only under those circumstances. And I remember a training flight where we flew through the Lyneham CTA IFR tracking CPT on a non-immune set: yes, we were in VMC, but we definitely got an IFR clearance...
Am I missing something, or was the article in 'Pilot' misleading?
Tim
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Just had a look on the CAA Web site and Schedule 5 of the ANO seems to be the chapter and verse on this. There is an issue of GASIL from 2001 here which gives a good summary on the front cover of the situation as I understand it, which goes as follows:
It should also be noted that there is a separate issue here - since the introduction of EASA on 28 Sep 03, they are now the regulating authority and the aircraft equipment approval process has been changed. There is a recommendation to contact the SRG at CAA.
Non-FM immune VOR and ILS receivers must be identified with a suitably worded placard and such receivers must not be used to comply with a requirement for the mandatory carriage of radio equipment. In the United Kingdom these requirements are set out in Article 15 and Schedule 5 of the Air Navigation Order (ANO). (Commercial air transport operators with JAR-OPS Air Operators Certificates should refer also to the requirements contained in JAR-OPS.). In addition, national aviation authorities in other countries are entitled to designate airspace where approved radio equipment must be carried.
For flight under instrument flight rules (IFR) in controlled airspace the legal requirements include one VOR receiver (which must be FM immune).To conduct an ILS approach inside or outside controlled airspace, one (FM immune) ILS receiver is required. The reference in Schedule 5 to duplicated VOR equipment relates to public transport IFR flights, whether inside or outside controlled airspace.
Note:This summary does not include all the radio and radio navigation equipment required by the ANO –for which the Order itself and Schedule 5 must be relied upon.
For flight under instrument flight rules (IFR) in controlled airspace the legal requirements include one VOR receiver (which must be FM immune).To conduct an ILS approach inside or outside controlled airspace, one (FM immune) ILS receiver is required. The reference in Schedule 5 to duplicated VOR equipment relates to public transport IFR flights, whether inside or outside controlled airspace.
Note:This summary does not include all the radio and radio navigation equipment required by the ANO –for which the Order itself and Schedule 5 must be relied upon.
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Yes, I found that GASIL too - that was why I went to the ANO. Interestingly there is an AIC listed in this year's LASORS on the subject, but when I looked for it on the AIS website it had vanished - withdrawn?
Not sure why the GASIL says you need FM immune ILS outside CAS, though - I can't find any justification for that in the ANO...?
Tim
Not sure why the GASIL says you need FM immune ILS outside CAS, though - I can't find any justification for that in the ANO...?
Tim
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Go back to the Pilot magazine quote. Add class 'D' and 'E' airspace to the list and then replace the word or with and and it reads right. A poorly worded statement on their part.
Then you were the bad boys for accepting the clearance. ATC doesn't know the state of the kit in your aircraft - you do and it is always the pilots responsibility to refuse a clearance which he is not entitled to accept.
Having said that did you actually state you were IFR or VFR, and did they actually give you a clearance that could have been construed as VFR or IFR? The reason I say this is my experience of Lyneham is not so much a clearance issued on the basis of flight rules as would be done in the civil world, but on the basis of what service you are receiving outside CAS. Nothing against the boys and girls there who do a sterling job, but just an observation from outside.
Think about why you need one full stop. It's all because of the protection required between ILS and radio broadcast stations which may be adjacent to the ILS band. After all - if you're doing a coupled approach then the ILS doesn't know whether it's inside or outside CAS - but it does know whether it's being interfered with or not with the associated safety ramifications 
And I remember a training flight where we flew through the Lyneham CTA IFR tracking CPT on a non-immune set: yes, we were in VMC, but we definitely got an IFR clearance...
Having said that did you actually state you were IFR or VFR, and did they actually give you a clearance that could have been construed as VFR or IFR? The reason I say this is my experience of Lyneham is not so much a clearance issued on the basis of flight rules as would be done in the civil world, but on the basis of what service you are receiving outside CAS. Nothing against the boys and girls there who do a sterling job, but just an observation from outside.
Not sure why the GASIL says you need FM immune ILS outside CAS, though - I can't find any justification for that in the ANO...?
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Surely one can fly around VFR without FM immune kit - this is what flying schools do. Very few training planes are FM immune.
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Thanks for that Chilli Monster - I do understand the safety implications of not having FM immune kit especially for ILS, it's just the legal side that was confusing me.
Out of interest, how many people renting from flying clubs/schools do have FM immune kit? I've never seen an FM immune radio...!
Tim
Out of interest, how many people renting from flying clubs/schools do have FM immune kit? I've never seen an FM immune radio...!
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Out of interest, how many people renting from flying clubs/schools do have FM immune kit?
I've this nagging feeling that the number of FM radios you require depends on whether you have a private or public category C of A, but I'll have to do some digging to confirm that
Brooklands
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Here is the AIC:
http://www.ais.org.uk/aes/pubs/aip/pdf/aic/4P007.PDF
http://www.ais.org.uk/aes/pubs/aip/pdf/aic/4P007.PDF
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Thanks for that Chilli Monster - I do understand the safety implications of not having FM immune kit especially for ILS, it's just the legal side that was confusing me.
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The requirement is in Schedule 5 to the ANO 2000, and is a requirement to have equipment to enable the aircraft to make an ILS approach, when landing at a 'notified' aerodrome. Since most use of an ILS will be when flying under IFR - since the pilot will not be able to comply with the VFR minima, the ILS needs to be FM immune.
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Thanks High Wing Drifter - that AIC is I think the source of the confusion, and I'm still confused. It states:
There's nothing in the ANO to support 'VFR flights only'. You only need specified equipment to fly IFR in CAS; outside CAS you simply need whatever equipment is necessary for you to fly the intended route. That route could easily be a mixture of NDB tracking and dead reckoning, in which case you don't need FM immune VOR/ILS equipment.
It could be referring to the COM radios... but in AN84 (thanks for finding that Justiciar) it says:
Tim
Airworthiness notice AN84 describes the airworthiness requirements for VHF communications and ILS/VOR navigation receivers... It should be noted that this AN requires all equipment not meeting the new FM immunity standards to be identified as so with a placard, and their use restricted to VFR flights only.
It could be referring to the COM radios... but in AN84 (thanks for finding that Justiciar) it says:
Recognising the reduced risk (of interference with VHF communications), paragraph 5 of this Notice permits a relaxation from the ICAO standard for VHF communication receivers carried in aircraft of 5700kg MTWA or less.
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There's nothing in the ANO to support 'VFR flights only'. You only need specified equipment to fly IFR in CAS
AN84 specifies non FM Immune instruments be limited to VFR only. That means that if you are making an approach for real in non VFR (i.e. IFR) then you must have FM immune. To stay within AN84 you would have to use the equipment in VFR, which defeates the purpose of the ILS other than in cases of training. The question of controlled or uncontrolled airspace is irrelevant to the use of a VOR/ILS, though would be relevant to the use of the VOR in uncontrolled airspace under VFR, which is permitted.
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As much as it hurt me to upgrade my Nav/Comms to FM Immune at the end of the day if there was not a risk then there would not be a requirement to have it done.
The last thing I wanted to find on an approach in bad weather was that the indications were incorrect becuase of FM interference.
At the end of the day IFR flying requires appropriate equipment and appropriate skills/practice, FM immune is just part of it.
It cost me US$600 to have 2 x Narco Nav/Comms made FM immune hardly a huger amount of money for safety?
The last thing I wanted to find on an approach in bad weather was that the indications were incorrect becuase of FM interference.
At the end of the day IFR flying requires appropriate equipment and appropriate skills/practice, FM immune is just part of it.
It cost me US$600 to have 2 x Narco Nav/Comms made FM immune hardly a huger amount of money for safety?
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I have been informed by an RAF engineer that the chance of there being any interference with non FM immune equipment is very very unlikely. In fact he went as far to say that in this country the risk is, at this time (a few months ago), theoretical.
I have not the knowledge to either agree or disagree with this, just wondering what the engineers in the forum think.
I have not the knowledge to either agree or disagree with this, just wondering what the engineers in the forum think.
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Sorry, talking at cross purposes. I accept that for instrument approaches (ILS or VOR) you would need FM immune NAV radios (in the real world I fly NDB or SRA approaches, in fact). What about en-route tracking of a VOR outside CAS but in IMC, though? That's an IFR flight so AN84 implies you can't do it legally, yet there's nothing in the ANO to prevent it - does AN84 override the ANO? Or does it come under the catch-all 'equipment required to complete the flight' bit?
Tim
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High Wing Drifter
I have asked and asked and have never come across anyone who has ever heard of FM interference having actually happened.
There are much bigger problems with light aircraft these days, e.g. electric fuel pumps affecting fuel totalisers, own radio transmissions affecting oil pressure indicators, own RF emissions or power bus spikes causing autopilot crashes, landing gear pumps causing avionics malfunctions, and while these things can be extremely irritating to say the least, none of these issues are certification issues because the equipment in question is not legally required to work.
But we must be charitable! The people who bring us these wonderful regulations have families to feed, just like the rest of us. We live in a redistributive society these days
I have asked and asked and have never come across anyone who has ever heard of FM interference having actually happened.
There are much bigger problems with light aircraft these days, e.g. electric fuel pumps affecting fuel totalisers, own radio transmissions affecting oil pressure indicators, own RF emissions or power bus spikes causing autopilot crashes, landing gear pumps causing avionics malfunctions, and while these things can be extremely irritating to say the least, none of these issues are certification issues because the equipment in question is not legally required to work.
But we must be charitable! The people who bring us these wonderful regulations have families to feed, just like the rest of us. We live in a redistributive society these days
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But we must be charitable! The people who bring us these wonderful regulations have families to feed, just like the rest of us. We live in a redistributive society these days
