Several times I've gotten in on an ILS when the weather was below the RNAV limits. There are quite a few RNAV approaches with minimums at 200 or 300, but certainly not everywhere.
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Panel planning - ILS and VOR or not?
- Thread starter Rick RV-4
- Start date
just to be fair, the opposite can be true as well. as an example - compare minimums for ILS and RNAV to rwy 04@KESN
Auburntsts
Well Known Member
Interesting but in my experience minimums that high on an ILS in the NAS is pretty rare.
I added an MGL Nav/Comm because why not. What's another few K, right??
They ought to give out free hand-held nav radios with all GA35 antennas.
Have you ever tried to actually fly an ILS using a handheld? I have...They ought to give out free hand-held nav radios with all GA35 antennas.
Yes. No picnic, to be sure, but I put it in the category of “better than nothing when you’re in IMC and your GA35 trashes all your GPS devices.”
When expressed as an overall percentage of cost for these projects, the VOR/ILS radio is not a significant factor. If you think you are going IFR and you want something to back up GPS, put it in the panel. Shooting an ILS with a handheld radio in IMC after losing your GPS is not the kind of thing 95% of us should be attempting.
Well I won't call you any of those things
but there's a big difference between punching through a layer at 800 AGL to depart, vs shooting an ILS down to 200 & 1/2.out of curiosity I compared Cat A DA minimums for the ILS (excluding CAT II/III and special authorization CAT I) with the corresponding GPS approaches. Here is what it looks like
1180 runways with an ILS approach:
30 don't have an RNAV corresponding to the ILS (eg KEWR RW04L).
262 RNAV DA is higher than the ILS (even if by 1 foot)
793 RNAVs with exactly the same DA as the matching ILS
95 RNAVs with better minimums than the ILS (even if by 1 foot)
4952 additional RNAV approaches to specific runways without an ILS (excluding circling only approaches e.g. GPS-A)i did not take into account NOTAMEd out, unmonitored, or downgraded to a LOC ILS approaches, so 1180 is a slightly optimistic number.
this data is available here by someone who parsed all of the FAA approach plates: https://github.com/ammaraskar/faa-instrument-approach-db/releases
(do not use for navigation
)For IFR: 91.205 (d)(2) Two-way radio communication and navigation equipment suitable for the route to be flown
I take exception with your LPV DA's being 400 and 500. I fly LPV's to 300' ceiling and a few 200' HAT. Your airports may be different. Just a note, VISABILITY is controlling more than ceiling. Many LPV's have 1/2 mile but I find often it is 3/4 or 1 mile. That is not NAV accuracy issue that is APPROACH &, RUNWAY Lights and markings and obstacles are the reasons. Many LPV's are at smaller airports with LESS bells and whistles, more obstacles. But to your point I already stated why ILS still has a edge on LPV in the lowest conditions, if your airport you operate has an ILS. It is a moot point if airport does not have an ILS. These terrestrial based IAP's are not as common as GPS RNAV. Top of my head there are 4 ILS in my general area and 20 LPV's. If you primarily fly into larger airports serviced by jets with ILS yes get :LOC/GS receiver and OBI/HSI... Most of the wiz bang Garmins G420W, GTN650 and GTN750 come with VOR/LOC/GS. Me? GPS 175 so GPS RNAV IAP is all I have and need.
Legality and personal mins. WHAT are you doing flying were ILS will save the day?
As you know for IFR flight, you shall get WX, NOTAMS. known delays, runway length, alternates (as req), required fuel and file. You know you need basically VFR at destination 1-2-3 rule, or file an Alternate. Alternate must have 600-2 and 800-2. ILS, does give you ability (if Alt airport has one) the ability to file to the lower 600-2 for rrecision approach. But really is 800-2 going to make a difference, considering a LPV nom typical is 200-1/2 to something well below 800-2.
Flying to low mins in your single engine single pilot sky scooter is not my thing. Oh I can do it. My students at the flight club do it under the hood. However if you are doing NEEDING to go low mins of an ILS, it may show bad planning. I use to fly night freight in the early 90's, old Navahos and Seneca's over cascade mountains, no GPS, single pilot. Not doing that again. I know people are going to say yeah but my plane is based on coast and we have fog and low mins all the time. OK then by all means get ILS capability. Personally I wait for it to burn off. I have nothing to prove or MUST get there.
Personal mins. I am not flying in a 2 crew Jet may be with HUD and FLIR... Talk of getting in on an ILS and that you can't with LPV is academic. At work I rarely fly to mins without seeing the runway. Yes I fly mostly ILS to big airports. In my personal plane I never go to those big ILS airports and GPS RNAV LPV is all I need. I can not see spending another $10,000 adding a boat load of wires, coaxial, antennas and weight to my plane for something that I might use 1% of the time. It is not an IFR trainer. It is a personal plane, and I am going plan and fly in weather where GETTING in is not a factor.
I do CFII at a flight club I belong. My students have to fly to mins under the hood to count. (It is an FAR). Or they go missed. It's not a matter of doing it but a matter of do I want or need to do it. ILS up to you.
Bottom line flight planning, and pilot currency, proficiency is for more important than a LOC/GS receiver. In my personal plane I am not launching if weather is below or expected to at mins: I flew IFR long ago in a Piper, with VOR/LOC/Marker Beacon, no ILS no NDB capability. However lots of VOR and LOC approaches I could do. Today almost impossible. GPS rocks. Most bang for bucks, safe, accurate. AREA NAV rules. PS Check GPS NOTAMS
Did you fly for AirPac?
Bon Turner Wrote:
I read the FARs differently. Both an ILS and an LPV may have 1/2 mile flight vis minimums.
Bon Turner Wrote:
This whole section does not differentiate between ILS or LPV. So IMHO the ‘you can descend to 100’ agl’ “advantage” applies equally well to LPV approaches. BTW, you won’t find 200’-1/2 mi minimums unless there’s an ALS. If flight vis is really just at 1/2 mile there’s nothing else to see.
I read the FARs differently. Both an ILS and an LPV may have 1/2 mile flight vis minimums.
( ILS is a Precision Approach and LPV is Non-Precision. Not saying you are wrong. To be clear we are talking 91.174 3(c)(i). )
Bon Turner Wrote:
This whole section does not differentiate between ILS or LPV. So IMHO the ‘you can descend to 100’ agl’ “advantage” applies equally well to LPV approaches. BTW, you won’t find 200’-1/2 mi minimums unless there’s an ALS. If flight vis is really just at 1/2 mile there’s nothing else to see.
You say does not differentiate? That is true. I see that. It does not specify either. We may be in an academic area or a gap in Regs that needs clarification. I will look at revision history or amendment level of this Reg. That can help. I swear I remember it being only for ILS.
LPV with 200-1/2 is likely an overlay on ILS, so it has ALS, because an ILS has to have ALS. I am sure some LPV's have ALS installed without an ILS somewhere. Most small airports are not going to do that for cost and land reasons.
So it is kind of academic and self limiting as you said "nothing to see". I suppose a LOC only to runway with a ALSF-2 cutting through the fog you can continue to 100 HAT. The question is being another 200 feet higher or more than the ILS with Vis at mins, likely not going to see the ALS. If LPV down to 200 HAT same as the ILS you may see the ALS. )
LPV being Non-Precision most runways with LPV IAP are serving non precision IFR runway standards, no/min ALS, basic runway markings and lights, and typically at least 5000' long. So it is moot issue. No ALS no "advantage". My home airport is rural and has REIL, two synchronized flashing white lights at threshold on each side. That is considered ALS but not something to fly to runway with.
Just last month I had a situation where a nav radio would have been necessary to save the day, had I been in IMC.
It's good that you have your personal minimums.
Other folks will have their own, and the ILS approach availability gives additional options.
While I am an advocate for proper planning, if you only fly in good VFR weather you lose quite a bit of utility in flying the aircraft especially in the midwest. If that's your thing, fine. I choose to have the added options available with the ILS.
one way to estimate the risk is to check the logbook and note the hours flown in actual imc per year. then take a realistic duration of the gps outages/spoofing events per yer in your area. ask chatgpt to calculate the probability of experiencing a gps outage while in IMC based on these numbers.
another chat gpt question would be how long you must be in IMC to experience an outage with some degree of certainty (eg 50%). based on that, a decision can be made if the ILS backup is necessary. just some pure arithmetic
another chat gpt question would be how long you must be in IMC to experience an outage with some degree of certainty (eg 50%). based on that, a decision can be made if the ILS backup is necessary. just some pure arithmetic
Do you apply that logic to the rest of the equipment related to the aircraft?one way to estimate the risk is to check the logbook and note the hours flown in actual imc per year. then take a realistic duration of the gps outages/spoofing events per yer in your area. ask chatgpt to calculate the probability of experiencing a gps outage while in IMC based on these numbers.
another chat gpt question would be how long you must be in IMC to experience an outage with some degree of certainty (eg 50%). based on that, a decision can be made if the ILS backup is necessary. just some pure arithmetic
Is a GPS receiver necessary? Nope.
Is a constant speed prop necessary? Nope.
Is a whiskey compass necessary? Nope.
Is a ballistic chute necessary? Nope.
A second com? Nope.
A backup attitude indicator? Nope.
The list is endless. Go ahead and ask your AI to calculate the probability of needing any of these things.
In the end, it is about what you want...just don't ask it to calculate the probability of needing an airplane, you likely won't like the answer.
i was trying to limit the question to the topic of this thread, and decide if it makes sense to spend resources on the ILS/VHF nav GPS backup, or focus on some other area related to safety. (I have a GPS only panel and fly IFR only for fun/training and occasional MVFR conditions).
If I had unlimited resources, sure I'd buy a no-compromise plane with triple redundant systems and with a brand new PT6 engine, enroll in the best possible recuring training, and pay for the top notch factory authorized maintenance. But that is just not on the plate unfortunately
It sounds like you already have your answer; for your mission, ILS equipment isn't necessary and you do not need the additional options it provides.i was trying to limit the question to the topic of this thread, and decide if it makes sense to spend resources on the ILS/VHF nav GPS backup, or focus on some other area related to safety. (I have a GPS only panel and fly IFR only for fun/training and occasional MVFR conditions).
If I had unlimited resources, sure I'd buy a no-compromise plane with triple redundant systems and with a brand new PT6 engine, enroll in the best possible recuring training, and pay for the top notch factory authorized maintenance. But that is just not on the plate unfortunately
Because forecasts are never wrong, right?
GPS only puts you in the soup, flying for real, with a single-point-of-failure for navigation. A GPS outage/jamming event or a broken antenna takes you out. You might be comfortable with that level of exposure, I am not. To each their own.
To your point, I don't plan to fly into 200 1/2 "for real" on any mission - but I certainly have made a handful of approaches to that minimum with the actual weather differing from the forecast, and I've made a few missed approaches at 200' when the weather was worse. Failing to plan is planning to fail, and all that.
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Austin Meyer has an interesting demonstration of handling a GPS failure by using inertial navigation. It turns out VHF nav and ILS is not the only way out of the pickle.
He posted this in the comments:
Outage caused by: THE LAV MICROPHONE. Crazy, but true. Every time I set up for recording, the GPS went out. True story. Took me a while to figure it out.
---
On today's flight I had total of 7 GPS/WAAS antennas: GPS175, Skyview, Stratux, iphone, Ipad, passenger's Iphone and Ipad (with forflight and fltplan.go). Some of these connect to more than just U.S. DoD GPS constellation, and can exclude faulty satellites. And thank goodness it was a VFR day on top of that. I felt safe!
He posted this in the comments:
Outage caused by: THE LAV MICROPHONE. Crazy, but true. Every time I set up for recording, the GPS went out. True story. Took me a while to figure it out.
---
On today's flight I had total of 7 GPS/WAAS antennas: GPS175, Skyview, Stratux, iphone, Ipad, passenger's Iphone and Ipad (with forflight and fltplan.go). Some of these connect to more than just U.S. DoD GPS constellation, and can exclude faulty satellites. And thank goodness it was a VFR day on top of that. I felt safe!
And this DOES happen, I can now assure you!
I'd just like to raise a related issue which I haven't seen discussed here: if you're relying on a nav radio to fly a VOR or ILS approach, you may want/need a DME receiver. In my [very limited] experience with modern IFR panels, almost everyone is relying on GPS-derived DME, which would obviously be down in the event of a GPS outage. There are many ILS approaches that cannot be flown unless you have DME, GPS, or radar service, because there are no off-field/perpendicular/maintained VORs to define a crossing radial.
Well.. If the GPS system is down, you're right, I have no DME... BUT, I feel safer shooting the approach with my NAV radio only than being stuck like chuck. I'd declare the E-word for all to hear so I would have the authority to disregard the regs to the extent needed to meet the emergency (paraphrasing).
So yes, Belt and Suspenders only. I don't know what the DME would be... Cumberbund? I'm not that formal.
I guess the question is how expensive/complicated would it be to add DME. Maybe not worth it in your view, but it bugs me a bit that the only tool I have for identifiying distance to a navaid is by GPS. It's moot in my own plane, which is VFR only, but every rented Cessna I've used is lacking true DME, no matter how fancy the IFR navigator (up to GTN 750s).Well.. If the GPS system is down, you're right, I have no DME... BUT, I feel safer shooting the approach with my NAV radio only than being stuck like chuck. I'd declare the E-word for all to hear so I would have the authority to disregard the regs to the extent needed to meet the emergency (paraphrasing).
So yes, Belt and Suspenders only. I don't know what the DME would be... Cumberbund? I'm not that formal.
Jerry Fischer
Well Known Member
Just a thought here...why take away all your options?
walkman
Well Known Member
"A recent failure of my GA-35 antenna successfully jammed all my other GPS receivers. "
I'd like to understand more about that.
As many (most?) of our receivers these days are actually multi-system (GLONASS, Galileo) would a GPS jamming incident affect the others? Can our systems operate on one of the other systems for an approach if GPS is out? Would the issue above (antenna failure jamming onboard GPS) also block the other systems?
I'd like to understand more about that.
As many (most?) of our receivers these days are actually multi-system (GLONASS, Galileo) would a GPS jamming incident affect the others? Can our systems operate on one of the other systems for an approach if GPS is out? Would the issue above (antenna failure jamming onboard GPS) also block the other systems?
Perhaps thread drift but how many of you have a wet compass in the plane? Only reason is one of those anecdotal events I was a part of one day flying "co-pilot" in a 210 Took off in MVFR on IFR plan, broke out on top every thing fine until the whole panel dropped electricity. No radio, no nothing except wet compass and old turn and bank indicator. We knew there was clearing air west of us. Managed to find broken clouds got down and under and with a paper vhf sectional found where we were and landed without problem other than the tower light gun wasn't working either.... I made a personal decision point that day, always have a compass and as much of a dinosaur it is, keep a paper sectional for the flight in the plane along with a pen light in reach. Added a handheld radio to the flight bag. Found out later it was a ground bus issue which is another story about avionics upgrades in older planes....Well.. If the GPS system is down, you're right, I have no DME... BUT, I feel safer shooting the approach with my NAV radio only than being stuck like chuck. I'd declare the E-word for all to hear so I would have the authority to disregard the regs to the extent needed to meet the emergency (paraphrasing).
So yes, Belt and Suspenders only. I don't know what the DME would be... Cumberbund? I'm not that formal.
Yep, drill down far enough and you can ALWAYS find a failure mode…
I removed my wet compass a couple of years ago. In your situation, I would have had a sectional (Foreflight), and would have been able to navigate with my iPad or iPhone . If GPS was down, I’d still have the sectional and I could use the compass app on either my Apple Watch, iPhone, or iPad (iPad requires a third-party app, and you’d have to make sure it was one that used the magnetometer and not dependent on GPS). Point being, the wet compass and its gyro companion are kind of unnecessary these days IMHO.
All I can tell you is that my GA35 took a dump, and when it did, not a single GPS receiver in my airplane (including my iPhone) worked. The freaking thing literally jammed them. If I had known that my 430W/GA35 was causing the problem (I thought it was some sort of GPS outage), I think I could have just turned it off and restored the other GPSs, but if so there goes my only nav radio. Probably could have faked a non-precision approach using the iPad, but if I had truly needed vertical guidance I was hosed.
Most modern gps antennas have amplifiers built into the antenna base (power comes up the coax). Some of them, (GA35 for example) apparently have failure modes where the amplifier gets ‘feedback’ and turns into a transmitter. Even a milliwatt radiated signal is huge compared to the signal from a satellite, so the receivers are overwhelmed.
This was all news to me, but it makes sense (and makes me wonder if there’s an alternative to the GA35).
I’ve been trying to come up with the right simile for this impressive failure mode. Still working on it.
i found it:
since you had a 430 with a toast GPS, was the ILS/VOR reception still functional and would it let you fly an approach?
“It’s as if getting a flat tire made all the car’s wheels fall off.”i found it:
since you had a 430 with a toast GPS, was the ILS/VOR reception still functional and would it let you fly an approach?
ILS/VOR appeared to be still functional. Apparently it takes more than a few milliwatts of GPS jamming to derail trusty 1950s radio technology!! No DME in my bird, so a bunch of approaches would still be “interesting,” but it would have been MUCH better than nothing.
As a ferry-pilot that gets into a different aircraft all the time, I will say that having an analog backup is an ideal situation. I think it is worth the 4 inches of panel space to drive a glideslope indicator off your modern GPS. It's a "Why wouldn't I take some redundancy and a backup?" scenario to me. I taught the scuba diving rescue course for a number of years and a lot of what I taught was the psychology and mindset to have in regards to dealing with anomalies or emergencies. I would tell people that they need to embrace the principle that "The best kind of rescue is self-rescue." Meaning, be set up and prepared to handle your own emergencies with a contingency plan before you become someone else's emergency and in turn put others at risk that have to come help you (or be impacted by your failure). Having a backup for an ils/vor/loc approach is smart planning in my book and worth the additional investment in equipment.
With all the low cost MEMs technology these days, I’m surprised there isn’t at least a low grade INS reversion on mainstream GA avionics.
Indeed. I can testify that the reversionary GPS “dead reckoning” mode is suboptimal.
walkman
Well Known Member
ugh
my panel is designed so that my gtn650 does not have an independent switch. it's on when the master is on and/or the e-buss is on. there's no separate switch. maybe I should install one. what are the comparative failure rates of PIDG connectors, carling G-series switches, and GA35's? I need to calculate my risk
If i hold the home button for 3 seconds on the GPS175 it will power off and that will remove power from the LNA in the GPS antenna as well. I would imagine most garmins have some sort of power off feature.
walkman
Well Known Member
unaware of anything like that in the GTN650
just pull the circuit breaker
walkman
Well Known Member
I don't have circuit breakers
I have ATC style fuses in a fuse block that is accessible from the forward baggage compartment.
Prior to this conversation I couldn't think of any reason I would want to disable my primary COM/NAV in flight.
I see quite a few posts about GPS antennas becoming transmitters presumably when the op amp oscillates after water ingress. Water disrupts a delicate balance in the op amp circuit. GA35 may be not better or worse than any other. May be some cracks can develop and let in moisture. Seem like a checklist item on loss of GPS should be to power off external antennas one at a time.
