wombat

@Hank Thanks for pointing that out. I assume that ATC tried to talk to him for a while before he actually entered the TFR, and they had other aircraft trying to talk to him before he entered it as well. But I've certainly had times when I was flying towards a TFR (Firefighting TFRs over the Cascades) and while I knew about them, ATC wouldn't necessarily say anything until maybe five minutes before. And even then I've had to remind ATC that the TFRs are 3 dimensional and they have a top, which I was usually above. So all said..... possible pilot deviation. But I don't know enough.

@GeeBee Don't know that it was unclear to anyone. But there is an open question of how long you can go without positive radio contact with ATC before action is required of you. My statement on this is that if he was flying his assigned clearance, his offense is not that of violating the TFR. Maybe he was violating 91.183, but that depends on how long it had been since he last talked to ATC. Also maybe depending on why he hadn't been talking to them. That being said, it sounds like the time he was out of contact was a lot more than 9 minutes. (When ATC does talk to him, they say the incident was "20 miles ago") And from the times of the events (26 minutes after the hour ATC was asking for other planes to help, and at 36 after the hour they finally talk to him) And I trust that ATC has been trying to contact him on all of the 'reasonable' frequencies for quite some time. But as an example of how this could happen in a way where this pilot isn't at fault, if you were flying North past KPDX on IFR, at 9,000' and you've been hearing ATC the whole time, but they just hadn't said anything to you personally after you passed Salem.....How long would you wait before saying anything? The IFR low charts say it's all Seattle Center... But below 10,000 you need to be talking to Cascade Approach or Portland Approach depending on the location. But you can still hear ATC talking to all the same folks going from Cali to Seattle or Alaska. And if you were 1,000' higher, you'd be on the right frequency. It's possible (although in my opinion, unlikely) that N91396's pilot did nothing wrong; the controller *could* have missed handing him off to Charlston Approach, and he was on the correct Center frequency and hearing traffic the whole time, just didn't make an active call to make sure they remember he's on frequency. So before I join camp "N91396 should be forcibly sold out from under this dude" I'd like to know more about what happened.

If you feel like you have nothing to do, it's probably because you are flying a Cessna 150 with a headwind. Not much more frustrating than to look at stop-and-go traffic on the interstate under me that is still passing me.

Agreed. I think we all agree that checking in if it's been 'too long' is a good habit. But how long is too long? I don't know of anywhere that has any guidance other than 91.183. Saying someone violated 91.13 for failing to do so in a timely manner after just 9 minutes since their last radio call doesn't seem right to me though. Why don't the regulations just tell us how long is too long? I don't want another airspace overlay that gives a time in minutes between mandatory two-way radio communications checkins. Is this something you are supposed to pick up in your IFR training? It should be in 91.167 – 91.199. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-F/part-91/subpart-B/subject-group-ECFRef6e8c57f580cfd And if so, it should be one of the requirements listed in 61.65 - Instrument rating requirements. https://www.ecfr.gov/current/title-14/chapter-I/subchapter-D/part-61/subpart-B/section-61.65 But exactly where is it in the regs? But maybe the FAA thinks that "Long enough to fly into an active TFR" is too long and is a violation of 91.13? I don't know, but I do know I never want that to be me! The AIM has some things to say about radio communications failure in chapter 6, section 4-1. , https://www.faa.gov/air_traffic/publications/atpubs/aim_html/chap6_section_4.html Specifically it says "pilots are expected to exercise good judgment in whatever action they elect to take"... But that's only if the pilot has realized that they are in that situation.

MOONIAC The best aviation related license plate I've ever seen was at the Seattle FSDO parking lot, a Porsche 9114S with plate "VNE"

I tend to think that the value of an airplane with upgrades is the cost of the 'base' airplane, plus the depreciated value (5% of the remaining value each year) of the upgraded hardware, but not including the cost to install the hardware. So if the plane is worth $100,000 and you put a $10,000 radio in it 5 years ago, spending $3,000 to install it, the plane is worth $100,000 + $10,000*(.95^5)) == $107,737. But of course anything less than $1,000 in this scale is a rounding error, outweighed by someone's particular preference for paint colors or avionics brand or if you sell the aircraft with a full tank of fuel. But the important part is that at most the plane is worth the base value plus the value of the installed upgrades, and if you are having the upgrades done, you will never recoup the cost of the labor to install it.

@exM20K 9 minutes? I'm a Western States (excluding California) pilot.... I get 9 minute blocks without hearing ATC talk to anyone else on the radio let alone talking to me. Now I do know there is a difference between flying out here and flying on the crowded Eastern Seaboard, and 9 minutes is acceptable out here but not out there. But how much wiggle room is there? 3 minutes? 90 seconds?

@lithium366 Perhaps it's not the cam that's worn but the tappet or some other connecting pin or part? But this is just going back to what you said at the very beginning. Found this article about measuring dry tappet clearance. Sounds like a bit of a hassle. https://www.kitplanes.com/maintenance-matters-36/

@GeeBee The things you say are not wrong, but.... I know you are not this extreme about it, but please follow along with my reasoning here... In my 182 I've only got one radio. Can't monitor guard. Maybe N91316 is in the same boat? (haha. A plane, in a boat!) It almost sounds like you are suggesting that any pilot who flies an aircraft without a second radio is in violation of 91.13. What would you think of a plane with no radio at all? Yikes! And what do I do about getting weather at my destination? Can't switch off of 121.5 because that's a violation of 91.13, right? So every airplane needs to have a dedicated radio just for 121.5? I really doubt that's what you are really suggesting; I took that to an extreme.And I really doubt that N91316 has only one radio. But this is exactly the sort of reason I don't like to invoke 91.13. Because what seems extreme to me might not seem extreme to you. This is why we have rules other than 91.13, so we have a document that says what is 'extreme'. A big part of my question here is when does it go from just a quiet frequency to lost comms ? 5 minutes? 50 minutes? The rules about that don't exist. 91.183 is what we've got and it has nothing to say about this. I've called up ATC a bunch of times just because things got quiet for 'too long' for my liking.

Another idea on N91316's actions.... Let's be generous and assume that when he took off, he had a full route clearance, but one that didn't keep him out of the TFR. (Not too unreasonable, since the TFR was probably not active then) And let's be generous again and assume that he was flying in accordance with that clearance the entire time. It sounds like he was out of contact with ATC for quite a while, but what standards are there for how often or when you need to check in with ATC? If his route had no IFR reporting points (91.183) and his last radio call had been to proceed direct to some point on the far side of the TFR, did he really violate the TFR? Or did he violate some other rule? If you are over BNA VOR and are told "Fly BNA 355 outbound, proceed to V24, then as filed." Well, V24 is 300+ miles away. When are you obligated to start making heroic efforts to talk to ATC again? Your next required radio call is a couple of hours away. 91.13 is perhaps an option, because we all know that if you are talking to ATC (and he's flying IFR, so he MUST be talking to ATC) you should be getting occasional radio calls from them to change frequencies if nothing else. I don't like to suggest 91.13 because what is one person's 'careless and reckless' is another person's every day. Example: One pilot told me when flying without ADS-B In, he once got to about 2 NM from another airplane in flight in the Bay area in California without seeing it despite having it called out to him from ATC. He was so freaked out by this he said he will NEVER fly without ADS-B in again and thinks that anyone that does should be violated under 91.13. I think he's... a bit extreme, to put it kindly. Regardless, a nice long conversation with the FAA is in order for at least that pilot.

I think @lithium366 has put quite a bit of thought into this. I agree with everyone that cylinder #4 is running rich, for the various reasons mentioned. He said he already did a fuel flow test and even tried swapping injectors. For me, that would confirm that the same amount of fuel per second is flowing to that cylinder. So... That leaves a reduction in the amount of air as the only other option as to why this cylinder is running rich. As he mentioned, valve clearances could be an issue. If the intake valve doesn't open as far as the rest of the cylinders, when the valve is open the mixture entering the cylinder will be richer than the others. I don't have any good ideas. A couple of bad ones that are really far fetched. Intake manifold partially blocked for just that cylinder? Exhaust manifold partially blocked for just that cylinder? Fuel injector lines for the other three cylinders all partially blocked by the same amount, so not restricted in low-flow applications, but only at high fuel flows? But blocking three of four by the same amount and in a way that doesn't get identified by the fuel flow test is unreasonable. Does the EGT peak difference happen at all power settings equally, or does it change if you lean at lower power vs. higher power?

Further thoughts on the cannulas.... While there is nothing prohibiting us from flying with a non-certified piece of equipment, there are rules in place prohibiting us from using equipment in a way that is prohibited, like flying above Vne. So while nothing in the plane says you can't use a cannula up to 25,000' (Again, ignoring the actual real-life safety issue here!!!), I suspect all of the cannulas we have have been certified, and their certification and operating limitations include not using it above 18,000'. If you were to find an uncertified cannula, you'd be legal. Although you'd be no safer. As far as the oxysaver cannulas and why they are only useful up to 15,000' from @jaylw314and @Schllc... They have very small reservoirs in them that are supposed to fill with oxygen during your exhale and then when you inhale, they provide a flow rate that is higher than the nominal flow rate from the bottle. But as the required flow rate increases, the capacity of the reservoirs is exceeded. If you breathe out quickly and inhale slowly, they'll conserve oxygen the whole time. But relying on a specific breathing pattern to maintain awareness sounds like a recipe for failure.

I'm no medical expert. Here is what I think is going on... I think it takes more than 9 seconds for the oxygenated blood in your lungs to reach your brain, so there has to be something going on that acts on your entire circulatory system at the same time. So if we consider the pressures and partial pressures, and pressure differentials, how about this as a theory.... Your cells need a oxygen pressure differential in order to oxygenate themselves that is an absolute differential. Let's call it 0.5 PSI (I'm sure anyone with medical training is screaming in their heads on on their keyboard at me right now! Just be glad I didn't measure it in cars per football field). So without a 1 PSI difference in the partial pressure of the oxygen in the blood and the partial pressure of oxygen in the cells, the cells will not absorb the oxygen in the blood. So when the atmospheric pressure is 3 PSI (21% of 14 PSI) your blood has maybe 2.5 PSI, and then your brain cells have 2 PSI. Life is good. When the atmospheric pressure drops 7 PSI (18,000'), the air has 1.5 PSI, blood now has 1 PSI and your brain cells have 0.5 PSI. Not good but not instantly deadly. When the atmospheric pressure drops to 3.5 PSI, the air has about 0.75 PSI, blood has 0.25 PSI, and the brain... Has nothing. This is just a half-baked theory. I did have a cup of earl grey tea this morning, but I did not stay at a Holiday Inn Express.

@MikeOHI agree with you that the AFM is compulsory. But the FAR they call out in the page Lancecasper posted is about aircraft certification, not about operation. If you want to certify a oxygen dispensing unit, you must comply with 23.1447. Otherwise, it doesn't apply. And I'm only interested in the legal aspect of this. Could I circle around above FAA headquarters at 18,001 feet, live-streaming myself on a cannula and not get busted? Considering I have 17 other pilots in the aircraft each on independent oxygen systems with pressure masks and immediate access to the controls and whatnot to prove that it's actually 'safe'.

My first message on this thread said "If the individual scales are not level, they might be measuring wrong. " I didn't put any thought into how much they would need to be individually unlevel to have a meaningful impact, but also made no reference to the relative elevation difference between individual scales. After that, my next post was agreeing with @EricJ's statement about the normal force on the scale not being aligned with the measuring axis of the load cell causing error. Including his statement that the error was small for small angle changes. Next I agreed with @Hank and gave an example where the aircraft was level but the scales were not, which would result in error. Again, I didn't address the relative quantity of error in relation to the angle of the scales. @1980MooneyUnless someone deleted or edited their posts, the only times the word 'lower' has been used in this thread before page 3 is when you said it, and then when you said "He didn't say tilted scale, he just said lower", or when you talked about the right wing being lower than the left side. Or when others were quoting you. So in summary, we all agree on the following things If the individual scales are level, even if the aircraft isn't, the total weight measured will be accurate. If the individual scales are not level, even if the aircraft is, the total weight measured will be lower than actual. If the aircraft is level and the scales are level, the weight and the balance will be accurate. (Please, nobody bring up if the scales are calibrated!!!) If the aircraft is not level, the balance measurements will be wrong, regardless of if the scales are measuring correctly or if the total weight is correct. The amount that the individual scales would need to be tilted by in order to have a meaningful impact on their measurements is unreasonably large to be a factor in real-life aircraft measurements.

@MikeOH Mostly I agree with you, but I don't think it says there is a limitation. It says "The FAA Approved flow devices consist only of.(blah, blah, blah)..that are calibrated and adjustable for altitude to supply oxygen to ...(paraphrasing) differnt types of cannulas (end paraphrasing) up to 18,000" So they simply say they are calibrated up to 18,000' for cannulas, or masks for higher.

@MikeOH The way I read it, 23.1447 is a certification requirement for the aircraft. For me, as a pilot of the aircraft, I MUST abide by the POH (Example: Vne). But while the POH offers some helpful information about cannulas, such as "The FAA Approved flow devices consist of..." and it also offers advice, "...information that should be observed when operating..." there is nothing in that text that is mandatory or prohibited. What is mandatory is that for any time above 14,000 MSL the entire minimum flight crew must use supplemental oxygen. But there is no language in part 91 about what equipment counts as supplemental oxygen. So from my perspective, if you have a bunch of party balloons filled with oxygen in the cabin (Bad idea! Don't do this!!!) and breathe from them like you are making your voice squeaky with helium balloons, you have met the letter of the law. (Again: Bad idea! Don't do this!!)

@A64PilotCan you switch which rules you are flying under mid flight? "The first part of the flight was part 137, then after my lass pass, I switched to part 91 and proceeded back to my home airport." If you can't switch in flight, can you switch when you do a touch-and-go? Or do you have to come to a full stop? Or do you have to shut down and start back up? Or does the pilot have to get out then back in? Do they need to get on the ground, or is just getting out of the cockpit sufficient? 137.42 says "No person may operate an aircraft in operations required to be conducted under part 137" so if the operation you are doing is required to be part 137... But what exactly is 'an operation' ? If you are actively dispensing product, sure.... But what about the turn at the end of a pass? Or after you are empty, heading back to refill? Can you take the shoulder harness off then?

@A64Pilot regarding shoulder harnesses.... 91.107(3) says "Except as provided in this paragraph, each person on board a U.S.-registered civil aircraft (except a free balloon that incorporates a basket or gondola or an airship type certificated before November 2, 1987) must occupy an approved seat or berth with a safety belt and, if installed, shoulder harness, properly secured about him or her during movement on the surface, takeoff, and landing." So if you can detach the shoulder harness portion without detaching the lap belt portion, you can have the shoulder harness off in flight other than takeoff and landing. And oddly enough, for seaplanes during movement on the surface, the person pushing off or mooring at the dock are excepted. But not just for the time period during the docking and mooring, the whole movement on the surface time. And only if you use a dock, beaching doesn't count. So if I was interested in malicious compliance, I could fire up one of my various amphibious seaplanes, taxi around on wheels and the floats, and as long as during that operation I moored or pushed off from a dock, I wouldn't need to have my seatbelt on at any point. So if I'm returning from a flight, landing on the runway (gear DOWN!) and I see my least favorite FAA inspector standing in front of my hangar with binoculars and a large format picture of my in the plane without my seatbelt on, I can taxi over to the water, find a dock, get out and moore then push off the plane, get back in, taxi back to my hangar and at that point it's all legal. Weird.

To me this is a really interesting discussion, everyone! Thanks for keeping the discussion civil and researching and debating this topic! I know some other threads have turned argumentative and emotional, but this one is going pretty much exactly as I had hoped. While I have no intentions of using a cannula above 18,000', I do like to understand precisely what I am legally required to do, and why. @LANCECASPER That page from the POH is really interesting and has some critical phrases and words. Thanks for posting it! Also, I think it contains a mistake. The important words are 'should' instead of 'must'. "Should" is not a legal requirement. And the mistake is that they say facemasks are required above 18,000ft per 23.1447. 23.1447 is Equipment standards for oxygen dispensing units and it says "If certification for operation above 18,000 feet (MSL) is requested, each oxygen dispensing unit must cover the nose and mouth of the user." I can't find a link to the FAA's website for it, but here is a link to elaws.us: http://federal.elaws.us/cfr/title14.part23.section23.1447 I don't know enough part 135 or 121 regulations to be confident, but I expect that they would require the use of FAA certified equipment for supplemental oxygen. But part 91 has no language that requires it. The FAA can write regulations that require the use of certified equipment, and has demonstrated so in their transponder regulations (See 91.215 and 91.413) but they chose not to do so here. I conclude that their intent is not to fully limit part 91 operations to only full face masks, despite a random brochure someone at the FAA put together.

Beauty is in the eye of the beholder and interpretations are in the eye of the reader. If I wrote something that is being misinterpreted, the fault is at least partially mine. What I was specifically trying to address was the error of each scale because the scale is not level which would be the case if the entire floor is not level.. As @Hank gave as an example (a better example than mine), a floor that slopes down toward the center, the aircraft wheels are both at exactly the same elevation but the scales they are sitting on are sitting on a slope. Each scale will individually read less than the true weight that is on it. They would have the same relative error if the entire floor was sloped the same direction, which is the example I was using.

I read that brochure, but it's not regulatory. And the brochure says that cannulas are restricted by federal aviation regulations, which may be true, but... Which regulation? The best idea I have right now is that all of the manufacturers of cannulas are trying to get some sort of FAA certification for their equipment for all of the part 135 operations, and in order to do that they need to meet specific requirements, and those requirements include prohibiting use above 18,000'. So if you buy one for aviation use, you would be using it against the manufacturer's requirements above18,000'. But how does this limit a part 91 pilot? If I simply sucked on a pipe end attached to the end of a hose plugged into the oxygen system, would that be illegal as a part 91 flight? Again, I'm completely ignoring the question of if this safe, or a good idea, or anything other than just the legal aspect.

Let's talk rules for a moment... Not talking safety here, just talking about legality. What says I can't use a cannula above 18,000' ? Conversely, is there anything that explicitly allows me to use use a cannula only below 18,000'? And also prohibits me from using a homebuilt system? Or just breathing in on the end of the hose? FAR 91.211 does not have anything to say about this FAR 25.1447 is about transport category aircraft FAR 23.1443 is about continuous flow oxygen equipment installed in aircraft (Normal, Utility, Acrobatic, and Commuter Category)

Yup, that's what I was demonstrating. Originally I phrased it something like "If the individual scales are not level, they might be measuring wrong" And the original situation I was envisioning is that the airplane is parked on a sloping smooth surface. So not only is the airplane not level, any load cell (or scale) will also not be perpendicular to the earth's gravity.

@Fly Boomer I can't find many wrist-only devices that have oxygen saturation. For example the fitbit charge 5 *can* but it is geared toward sleep oxygen measurements. But there are some that have the sensor near the base of the thumb. I still don't know what (if anything other than my regular oxygen sensor) I'll get. @hais Regarding setting a vertical descent rate in hopes of regaining consciousness.... I worry that will be ineffective because I think what would happen to me is that I'd fall asleep. Then as I descend I'll remain asleep, not unconscious. I know the times I've felt more severe symptoms of hypoxia I've been really sleepy. But that's a heck of a better option than doing nothing at all. And it's free!