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(thomassen@theunion.net@66.81.54.22) by mail.fullspectrumia.com with SMTP; 17 Nov 2005 05:45:37 -0000 Mime-Version: 1.0 (Apple Message framework v622) X-Original-To: lml@lancaironline.net X-Original-Message-Id: Content-Type: multipart/alternative; boundary=Apple-Mail-1--719336172 From: Keith Thomassen Subject: More IFR/GPS X-Original-Date: Wed, 16 Nov 2005 21:51:26 -0800 X-Mailer: Apple Mail (2.622) --Apple-Mail-1--719336172 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=WINDOWS-1252; format=flowed From: thomassen@avionicswest.com Subject: More IFR/GPS Date: November 16, 2005 1:34:22 PM PST To: lml@lancaironline.net My earlier note =93Navigating in the IFR system in an experimental=20 aircraft," stimulated lots of good discussion so I wanted to respond to=20= some points that were raised. These comments fell into a few areas,=20 Primary vs Supplemental use of GPS, FAA approval of equipment, and =93The=20= Rules=94. Primary/Supplemental GPS use There were many comments on =93ground based systems=94 for navigation =96 = if=20 you use them. Clearly the TSO 146 (WAAS) receivers don=92t use ground=20= based systems and yet they are legal for primary navigation. With them=20= you don=92t need to have VOR=92s in range, and you don=92t even need a = VOR=20 receiver in the airplane. However, as was pointed out, the controller=20= won=92t give you that route if he can=92t see you on radar. But, if you = go=20 IFR VFR on top when out of radar coverage, you=92re ok (and this is an=20= IFR flight plan). Having the capabilities of primary GPS nav equipment=20= is the key =96 and it doesn=92t have to be certified. Experimental = Chelton=20 systems that use the certified Chelton Free Flight GPS and integrity=20 software are prime examples of non-TSO=92d GPS's that have the=20 capabilities of LNAV-only TSO146 certified receivers. If you have a TSO 129 receiver (Garmin 430/530/1000 for example) you=20 are not allowed to use your GPS out of VOR range, because a RAIM=20 failure will render the GPS useless. You do have an option to ask ATC=20= for a clearance that might read, =93fly heading abc until receiving the=20= xyz VOR, then proceed direct=94. What this has done is to make your=20 directional gyro your primary navigation instrument, not your GPS,=20 until you can receive the VOR. If they can=92t see you on radar, you = are=20 out of luck. For these receivers, your primary system is always ground=20= based. Note that when you file /G nobody knows if your receiver is=20 primary or supplemental so it's up to you to play by the rules. FAA approved Equipment There were comments on local FSDO approval of equipment, a POH=20 supplement, AC20-138A, and the like. These statements in my view were=20= correct for certified aircraft. When you put equipment in certified=20 aircraft the FAA controls what happens. Whether you make a major or=20 minor alteration (file a 337 or not) equipment must be TSO=92d and for=20= IFR GPS=92s the shop needs to write a supplement to your POH. But what approvals are required for experimental aircraft? Here I=20 think is the can of worms. The only time the FAA is supposed to get=20 into the act is in the original signoff of your aircraft. If they=20 don=92t restrict you to VFR you should get a statement that makes 91.205=20= applicable to you if you want to fly IFR in the system. I know there=20 is a lot of local variation in what the FAA wants to see in your=20 airplane before they give you your certificate, but if you=92ve jumped=20= that hurdle and want to add an IFR GPS later, you as the manufacturer=20 can do that without their intervention. I=92m not aware of a = requirement=20 for a POH when you get your airplane signed off originally, let alone=20 for a supplement when you put in your GPS. These things are required=20= for certified airplanes. There was a reference to a shop refusing to install a micro-encoder=20 (not TSO=92d) without a FSDO signoff. If this was part of the original=20= FAA approval, and the FSDO wouldn=92t give that approval without=20 installing an inferior TSO=92d unit, he may have been out of bounds in = my=20 view, but clearly in control. This is a typical case of inconsistency=20= in the FAA. There are a lot of TruTrak autopilots in experimental=20 airplanes, and they are not TSO=92d . Nor is that fantastic engine=20 monitoring system (MVP-50) from EI. Why not object to these on the same=20= grounds? Objections should be based on the instrument requirements of=20= 91.205 and nothing else. The Rules There were a number of references to AC20-138A as the rules for all=20 aircraft with GNSS. I learned that Advisory Circulars are not rules,=20 they are advice. They do not govern what you need to do to fly IFR. =20 As I said in my article, I believe that Part 91.205 is both necessary=20 and sufficient for IFR flight. The EAA summary I referred to in my=20 article agrees with that. For those of you who haven=92t seen that=20 summary, I will send their pdf file on request. Keith Thomassen Avionics West Training thomassen@avionicswest.com --Apple-Mail-1--719336172 Content-Transfer-Encoding: quoted-printable Content-Type: text/enriched; charset=WINDOWS-1252 0000,0000,0000From: 0000,0000,0000 =20 thomassen@avionicswest.com 0000,0000,0000Subject: 0000,0000,0000 = More IFR/GPS 0000,0000,0000Date: 0000,0000,0000 November 16, 2005 1:34:22 PM PST 0000,0000,0000To: 0000,0000,0000 =20 lml@lancaironline.net TimesMy earlier note =93Navigating in the IFR system in an experimental aircraft," stimulated lots of good discussion so I wanted to respond to some points that were raised.=20 These comments fell into a few areas, Primary vs Supplemental use of GPS, FAA approval of equipment, and =93The Rules=94.=20 Primary/Supplemental GPS use There were many comments on =93ground based systems=94 for navigation =96 = if you use them. Clearly the TSO 146 (WAAS) receivers don=92t use ground based systems and yet they are legal for primary navigation. With them you don=92t need to have VOR=92s in range, and you don=92t even = need a VOR receiver in the airplane. However, as was pointed out, the controller won=92t give you that route if he can=92t see you on radar.=20= But, if you go IFR VFR on top when out of radar coverage, you=92re ok (and this is an IFR flight plan). Having the capabilities of primary GPS nav equipment is the key =96 and it doesn=92t have to be certified.=20= Experimental Chelton systems that use the certified Chelton Free Flight GPS and integrity software are prime examples of non-TSO=92d GPS's that have the capabilities of LNAV-only TSO146 certified receivers. If you have a TSO 129 receiver (Garmin 430/530/1000 for example) you are not allowed to use your GPS out of VOR range, because a RAIM failure will render the GPS useless. You do have an option to ask ATC for a clearance that might read, =93fly heading abc until receiving the xyz VOR, then proceed direct=94. What this has done is to make your directional gyro your primary navigation instrument, not your GPS, until you can receive the VOR. If they can=92t see you on radar, you are out of luck. For these receivers, your primary system is always ground based. Note that when you file /G nobody knows if your receiver is primary or supplemental so it's up to you to play by the rules. FAA approved Equipment There were comments on local FSDO approval of equipment, a POH supplement, AC20-138A, and the like. These statements in my view were correct for certified aircraft. When you put equipment in certified aircraft the FAA controls what happens. Whether you make a major or minor alteration (file a 337 or not) equipment must be TSO=92d and for IFR GPS=92s the shop needs to write a supplement to your POH. But what approvals are required for experimental aircraft? Here I think is the can of worms. The only time the FAA is supposed to get into the act is in the original signoff of your aircraft. If they don=92t restrict you to VFR you should get a statement that makes 91.205 applicable to you if you want to fly IFR in the system. I know there is a lot of local variation in what the FAA wants to see in your airplane before they give you your certificate, but if you=92ve jumped that hurdle and want to add an IFR GPS later, you as the manufacturer can do that without their intervention. I=92m not aware of a requirement for a POH when you get your airplane signed off originally, let alone for a supplement when you put in your GPS. =20 These things are required for certified airplanes. There was a reference to a shop refusing to install a micro-encoder (not TSO=92d) without a FSDO signoff. If this was part of the original FAA approval, and the FSDO wouldn=92t give that approval without installing an inferior TSO=92d unit, he may have been out of bounds in my view, but clearly in control. This is a typical case of inconsistency in the FAA. There are a lot of TruTrak autopilots in experimental airplanes, and they are not TSO=92d . Nor is that fantastic engine monitoring system (MVP-50) from EI. Why not object to these on the same grounds? Objections should be based on the instrument requirements of 91.205 and nothing else. The Rules There were a number of references to AC20-138A as the rules for all aircraft with GNSS. I learned that Advisory Circulars are not rules, they are advice. They do not govern what you need to do to fly IFR.=20 As I said in my article, I believe that Part 91.205 is both necessary and sufficient for IFR flight. The EAA summary I referred to in my article agrees with that. For those of you who haven=92t seen that summary, I will send their pdf file on request.=20 Keith Thomassen Avionics West Training thomassen@avionicswest.com =20 = --Apple-Mail-1--719336172--