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/...My take on it is that the FAA doesn't now want to impose an outright ban on flight into known icing conditions, unless FIKI approved, in Part 91 as they know that it would have huge economic and political consequences. Further, it ignores the fact that there are non-FIKI birds, like all the Aztecs, which handle ice better than a lot of FIKI birds, but Piper never chose to certify them. So the FAA is playing the game of trying to talk pilots out of flying in the ice without banning it outright as the fact is that the professionals can do it safely without the FIKI system and a lot of hobby flyers are dangerous, even with a FIKI plane strapped on.
Probably saying much the same thing.
for reference, here’s the Part 135 requirement for flight in icing conditions...
(c) No pilot may fly under IFR into known or forecast light or moderate icing conditions or under VFR into known light or moderate icing conditions, unless—
(1) The aircraft has functioning deicing or anti-icing equipment protecting each rotor blade, propeller, windshield, wing, stabilizing or control surface, and each airspeed, altimeter, rate of climb, or flight attitude instrument system;
(2) The airplane has ice protection provisions that meet section 34 of appendix A of this part; or
(3) The airplane meets transport category airplane type certification provisions, including the requirements for certification for flight in icing conditions.
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One of the challenges of writing a good regulation is achieving an appropriate balance between benefit and burden. In the case of Part 91 and icing, it's a balance between safety (for non part 135 operators) and the economic costs that would result if you more or less effectively shut down a significant percentage of IFR flights for a significant percentage of GA aircraft for a significant percentage of the winter for a significant percentage of the country for flights conducted under part 91.
However, a second challenge of writing a good reg is anticipating how people will game that regulation as well as the unintended consequences to other parts within a title of the CFR that stem from changes in behavior caused by changes in another part of the same title in the CFR.
I posted this example, in another thread on a different topic, but it points to the unintended change in behavior relative to one part of the regulations that can result from a change in another in another part of the regulation.
I was flying home in a C-172 after dropping the DPE off at his home airport following my instrument checkride. He advised me that I would need to file IFR to get home, while he typed up my certificate, and I did so. I checked the weather and there was no forecast icing or pilot reports of ice along the route or at the destination. There was however a fast moving front (in a big flat state out west where reporting stations were few and far between). I flew upwind about 70 miles into a 30 kt headwind, IFR on top. The cloud tops were at around 3800 ft MSL with a field elevation around 1430 ft and a ceiling that was pushing minimums at about 1700 ft MSL. (about a 2100 ft thick layer of clouds). As I approached my destination, I listened to the ATC chatter and a few minutes before I reached the IAF for the ILS 21 approach a 737 reported "trace" icing. That got my attention, and I realized that ATC was also keeping aircraft high and having them stay above the clouds and then descend through the outer marker rather than maintain 3100' motoring from the IAF to the outer marker. It didn't alarm me, but it probably should have. However as a newly minted instrument pilot with literally still wet ink on my certificate, I didn't know enough to realize what I didn't know about the enormity of what I still didn't know.
ATC did the same with me keeping me a above the clouds and dropping me quickly onto the outer marker and the glide slope. However, about 60 seconds after descending through the OM, and about 2 minutes after starting the descent and entering the cloud deck, I noted I had to maintain a lot more power than usual to maintain 90 kts on the glideslope. I pulled a flash light out of my pocket, shined it out at the leading edge and noted about a 1/2" of ice. I'd flown much of my instrument training that winter in actual IFR and I'd seen "trace" ice before. This wasn't that. This was ice that was accumulating very rapidly. I was now about 1600 ft below the cloud tops and given the amount of power needed to maintain the glide slope, and the additional ice I'd collect on the way back up, it was obvious the aircraft was not going to climb back above the clouds with the load of ice it currently had.
I added full power and increased the approach speed, to both reduce the AoA and also reduce the time on approach. I also accepted that there would be no missed approach possible. As I approached the inner marker and decision height I had to start converting excess speed to altitude to try to maintain the glideslope, and at best glide speed I had to start watching the GS needle slide out of the bottom of the donut. At that point I broke out at about 200' and had the runway approach lights on the nose. I barely made it over those lights to land.
The chief flight instructor/FBO owner was still at the FBO waiting for me when I taxied in and parked. We both noted over an inch of rime ice on the wing and significant ice on the prop. He was as mortified as I was that'd I'd picked up that much ice in less than 4 minutes in the clouds. We debriefed and I described the lack of forecast ice and the pilot report of "trace" ice shortly before I began the approach. He explained that pilots often report trace ice when there was significantly more ice as anything greater than trace ice would close the airport to any aircraft that was not certified for flight into known icing conditions. That's a direct (and predictable) result of pilot behavior changing in unintended ways by the wording in a regulation. He also advised that what might be plausible trace ice to a 737 is much more significant to a GA aircraft. I indicted that would have been great information to have that morning, as if I'd known that I'd have most likely skipped the approach and flown back downwind to my alternate and spent the night.
It left me with a permanent bias about the validity of "trace" ice reports, and about how much ice you can pick up in a normal descent through just 2100 ft of clouds.