GPS as ADF substitute
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Bookworm:
I have been doing a bit of checking through the ANO in my spare time (sad, I know).
As far as I can see, you are right that the schedule of radio equipment to be carried unde IFR outside CAS makes no mention of ADF (or any other nav equipment, for that matter).
What might catch you legally is Article 14 (7) which says that any equipment used for navigation, including 'information from selected celestial bodies'(or something like that) must be approved by the CAA. As I understand it a GPS fitted into an aircraft becomes a mod which must be approved. A handheld one doesn't, provided you don't attach it to the yoke.
In addition, Article 15 says equipment carried must be in a serviceable condition and of a type approved in relation to the purpose it is used. If GPS is not approved as an ADF substitute then you are stuck.
Article 16 says that all radio equipment must be approved. Does GPS come under radio equipment?
What I couldn't find were any details on the approval or otherwise of GPS. However, it is clear that you must not descend below MSA except for purpose of landing and on an approach procedure unless you are below 3000' AMSL and clear of cloud and in contact with the ground. As far as I know there are no approved GPS approaches in this country.
So we are not much further legally, but I still stand by my original comments. Sorry for the tedious type of reference to the ANO, but you started it!
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"Take-off is optional, Landing is mandatory"
I have been doing a bit of checking through the ANO in my spare time (sad, I know).
As far as I can see, you are right that the schedule of radio equipment to be carried unde IFR outside CAS makes no mention of ADF (or any other nav equipment, for that matter).
What might catch you legally is Article 14 (7) which says that any equipment used for navigation, including 'information from selected celestial bodies'(or something like that) must be approved by the CAA. As I understand it a GPS fitted into an aircraft becomes a mod which must be approved. A handheld one doesn't, provided you don't attach it to the yoke.
In addition, Article 15 says equipment carried must be in a serviceable condition and of a type approved in relation to the purpose it is used. If GPS is not approved as an ADF substitute then you are stuck.
Article 16 says that all radio equipment must be approved. Does GPS come under radio equipment?
What I couldn't find were any details on the approval or otherwise of GPS. However, it is clear that you must not descend below MSA except for purpose of landing and on an approach procedure unless you are below 3000' AMSL and clear of cloud and in contact with the ground. As far as I know there are no approved GPS approaches in this country.
So we are not much further legally, but I still stand by my original comments. Sorry for the tedious type of reference to the ANO, but you started it!
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"Take-off is optional, Landing is mandatory"
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The posts so far don't seem to address the basic reliability and accuracy concerns with GPS. Without preprogrammed RAIM monitored approaches (which exist in many places for non precision type letdowns) the use of the system entails an unpredictable risk. Likewise with holding if there is a concern with traffic separation or terrain clearance (as in protected areas).
GPS is great as a backup tool and for assisting with the initial above MSA tracking into the often poor range of an NDB .... but, without the added reliability of RAIM and DGPS for more precise approaches, it is a bit of a suckerbait system.
It horrifies me to see GA pilots here program their own versions of the published letdowns .. and then proceed to fly them ....
[This message has been edited by john_tullamarine (edited 04 July 2001).]
GPS is great as a backup tool and for assisting with the initial above MSA tracking into the often poor range of an NDB .... but, without the added reliability of RAIM and DGPS for more precise approaches, it is a bit of a suckerbait system.
It horrifies me to see GA pilots here program their own versions of the published letdowns .. and then proceed to fly them ....
[This message has been edited by john_tullamarine (edited 04 July 2001).]
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<font face="Verdana, Arial, Helvetica" size="2">I have been doing a bit of checking through the ANO in my spare time (sad, I know).</font>
<font face="Verdana, Arial, Helvetica" size="2">What might catch you legally is Article 14 (7) which says that any equipment used for navigation, including 'information from selected celestial bodies'(or something like that) must be approved by the CAA. As I understand it a GPS fitted into an aircraft becomes a mod which must be approved. A handheld one doesn't, provided you don't attach it to the yoke.</font>
<font face="Verdana, Arial, Helvetica" size="2">In addition, Article 15 says equipment carried must be in a serviceable condition and of a type approved in relation to the purpose it is used. If GPS is not approved as an ADF substitute then you are stuck.</font>
<font face="Verdana, Arial, Helvetica" size="2">Article 16 says that all radio equipment must be approved. Does GPS come under radio equipment?</font>
<font face="Verdana, Arial, Helvetica" size="2">What I couldn't find were any details on the approval or otherwise of GPS.</font>
<font face="Verdana, Arial, Helvetica" size="2">However, it is clear that you must not descend below MSA except for purpose of landing and on an approach procedure unless you are below 3000' AMSL and clear of cloud and in contact with the ground. As far as I know there are no approved GPS approaches in this country.</font>
Rule 29 says:
"Without prejudice to the provisions of rule 5, in order to comply with the Instrument Flight Rules an aircraft shall not fly at a height of less than 1000 feet above the highest obstacle within a distance of 5 nautical miles of the aircraft unless:
(a) it is necessary for the aircraft to do so in order to take off or land;
(b) the aircraft is flying on a route notified for the purposes of this rule;
(c) the aircraft has been otherwise authorised by the competent authority; or
(d) the aircraft is flying at an altitude not exceeding 3000 feet above mean sea level and remains clear of cloud and in sight of the surface."
It says nothing about "on an approach procedure" or anything of the sort. Just if "it is necessary for the aircraft to do so in order to take off or land".
What seems to be "obvious" but missing is any requirement to:
a) make use of an IAP
b) use particular equipment when flying an IAP
Let's just get this thing in perspective. I'm not seriously suggesting that it's wise to make up approach procedures, or rely on a handheld GPS in circumstances when it's operation is critical. (I think it's equally if not more daft to rely on an ADF!) What I am saying is that outside controlled airspace UK air law places few restrictions on the pilot to operate in a particular way. That requires a healthy and thorough attitude to risk management.
I think that the attitudes pushed by the CAA of continually damning GPS distort the ability to manage risk and present an unhelpful picture which is at odds with most pilots' everyday experiences. When you keep getting "advice" which is blatantly at odds with experience and common sense, you learn to ignore it. There are real risks with GPS.
I do not believe that the CAA does pilots any favours by accepting 'status quo' technologies, while placing great burdens on the introduction of new and clearly superior technologies. The FAA has had a GPS overlay program for more than 5 years, and I've not even read of an incident let alone an accident attributed to a GPS approach.
It's all very well for AP to sit there and say to airport operators "sure, we'll consider your request for a GPS approach -- just make out the cheque to...". The FAA had the foresight to realise that GPS could be an enormous benefit to civil aircraft safety, and to move forward in a way that improved overall IFR safety. But it wasn't invented here, was it?
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I've just emerged from reading the US FAR/AIM (sad, but necessary towards the FAA IR). That has some stern warnings about use of GPS, and some very enlightened ones.
RAIM is NOT the same as DGPS - your panel-mount IFR-approved GPS cross-checks itself against "spare" satellites and yells if it thinks it's going skewed. Your handheld/yoke mounted doesn't. You'd get into hot water rapidly using a handheld for navigation in the US.
I've sat in the jumpseat of an IFR commercial flight using enroute GPS, and it was most impressive. Cleared direct from Stansted to Düsseldorf, just like that. I'd like one...
But meanwhile, keep practising the NDB holds, just in case. The CAA might get you on "lacking in airmanship" otherwise!
RAIM is NOT the same as DGPS - your panel-mount IFR-approved GPS cross-checks itself against "spare" satellites and yells if it thinks it's going skewed. Your handheld/yoke mounted doesn't. You'd get into hot water rapidly using a handheld for navigation in the US.
I've sat in the jumpseat of an IFR commercial flight using enroute GPS, and it was most impressive. Cleared direct from Stansted to Düsseldorf, just like that. I'd like one...
But meanwhile, keep practising the NDB holds, just in case. The CAA might get you on "lacking in airmanship" otherwise!
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<font face="Verdana, Arial, Helvetica" size="2">I've just emerged from reading the US FAR/AIM (sad, but necessary towards the FAA IR). That has some stern warnings about use of GPS, and some very enlightened ones.</font>
"Since ADF receivers do not have a flag to warn the pilot when erroneous bearing information is being displayed, the pilot should continuously monitor the NDB's identification."
We do all do that without fail, don't we?
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bookworm
.
I was thinking of a vastly similar user interface ie a needle pointing in a direction, but I accept this is not always the case.
A hold starts with you homing in on a set needle direction. Then you set off into no-man's land hoping you will manoeuvre some time later back onto your starting direction. The trick is guessing timings and drifts. Thus largely it doesn't matter which you use.
Well actually you are right. The GPS and VOR give you track, and thus drift. This is very helpful in guessing wind effects.
I once failed my IR because the wind was entirely opposite to forecast so I missed the hold timing by 20 seconds. With GPS or VOR perhaps things would have been very different.
<font face="Verdana, Arial, Helvetica" size="2">I'm amazed that you regard the three types of approach as similar. They have vastly different user interface </font>
I was thinking of a vastly similar user interface ie a needle pointing in a direction, but I accept this is not always the case.
A hold starts with you homing in on a set needle direction. Then you set off into no-man's land hoping you will manoeuvre some time later back onto your starting direction. The trick is guessing timings and drifts. Thus largely it doesn't matter which you use.
Well actually you are right. The GPS and VOR give you track, and thus drift. This is very helpful in guessing wind effects.
I once failed my IR because the wind was entirely opposite to forecast so I missed the hold timing by 20 seconds. With GPS or VOR perhaps things would have been very different.
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As this seems to hve turned into a general discussion on GPS use....
One of the problems I have found is it is normally so reliable that people have difficulty in beliving it can, and does, produce inaccurate positions from time to time.
A handheld unit, but fed from a "proper" aircraft aerial, gave some very wrong information around ORTAC last week. It was difficult to ignore the nice (wrong) display and use VOR/ADF instead - even though we both knew the GPS position was suspect !!
One of the problems I have found is it is normally so reliable that people have difficulty in beliving it can, and does, produce inaccurate positions from time to time.
A handheld unit, but fed from a "proper" aircraft aerial, gave some very wrong information around ORTAC last week. It was difficult to ignore the nice (wrong) display and use VOR/ADF instead - even though we both knew the GPS position was suspect !!
