When Icing Certification Made Sense

Certifying airplanes for flight in icing conditions is a fairly new regulatory concept, particularly for non-transport category airplanes. I know, everybody calls it FIKI for flight in known ice certification, but the rules, such as they are, call it icing, not known icing.

For decades airplane manufacturers installed ice protection equipment on a variety of airplanes with no certification implication at all. Deice boots were common in the 1930s on multi engine airplanes. Propellers were protected by slinging alcohol on the blade roots, and the same stuff was used to prevent ice formation on windshields.

Electrically heated propellers and windshield hot plates became common many decades ago. And the weeping fluid TKS anti-ice system dates back to WW II when it was used on British bombers. All of the Hawker 125 series jets use TKS starting in the early 1960s. TKS seems new to piston owners, but is nearly as old as boots in the ice wars.

Many thousands of GA twins from Beech, Cessna, Piper and others were equipped with boots and prop ice protection but nobody thought about certifying the airplane to fly in ice. The boots were tested at least some, they worked in terms of inflating on command, and usually broke the ice off.

Think of all of the Beech 18s and Cessna 400 series twins that slogged through all kinds of weather, including icing, working for a living. And they were not certified for icing. Neither was Piper’s Aztec or the initial run of Navajos. Or the Aero Commanders, or even the Learjet 23 or Saberliner.

The idea of certifying an airplane with ice protection for flying in icing made as much sense as certifying a weather radar equipped airplane to fly in thunderstorms. Radar helped you avoid the worst and the boots kept you flying while you escaped the ice. Everybody knew there were thunderstorms that could break the wings off, and that there is icing that can overwhelm any ice protection system.

Certifying for flight in icing really took hold as turbine engines came along. It quickly became obvious that ice building on the inlet to a turbine engine could choke airflow and kill the engine. Equally threatening was ice that built up on the engine inlet and then broke off and was swallowed in chunks that could destroy compressor and turbine blades. Something had to be done.

So standards of liquid water content and droplet size were devised to test engine inlet ice protection. Then the concept of testing and approving ice protection spread to the rest of the airplane. But the “rules” were contained in FAA advisory circulars, not actual certification rules, and the ACs applied only to transport category airplanes which weigh more than 12,500 for takeoff.

I’m not sure why, but in the 1970s Cessna decided to certify some of its piston airplanes for icing. The 337 Skymaster and 210 singles were first up. The only procedures that existed applied only to transport airplanes, not GA piston airplanes, but the FAA somehow adapted those standards to the 337 and 210 and they were certified for icing.

You don’t need much experience in weather flying to know that an ice certified 210 is not going to survive as much ice as a non-certified King Air, or Beech 18, or even Cessna 310. If nothing else the 210 engine would cook because ice buildup on the cowling restricted cooling air flow just at the time you needed every single horsepower to lug the ice the system couldn’t remove.

So now pilots were told it was OK to fly a “certified” piston single into icing. Before that pilots were told to stay out of icing, and if you find it activate the boots and change altitude, or course or do something to escape. Was icing approval a safety advance? I don’t think so.

There are thousands of airplanes—nearly all piston twins—that are equipped with ice protection but are not approved for flight in icing. Nor are they specifically prohibited from flying in icing. A perfect status, I say. If you know ice is there nobody flies into it. If you find icing, you do your best to exit. Who needs to certify that?

But it’s too late. The FIKI horse is out of the barn. Airplanes are being certified to fly in laboratory icing and pilots are given a level of comfort that may not be warranted. And now an AD is being issued to prohibit flight in icing for thousands of Cessna twins that were built and equipped under the old concept of not approved, but not prohibited. Icing should get every pilot’s attention no matter what the certification limitations of the airplane may be and new limitations shouldn’t change that.

I applaud icing tests and the improvements they can lead to. And I’m happy to see effective ice protection on a growing variety of airplanes. But I much prefer the old attitude that ice protection helps you escape, but there are icing conditions out there that can bring down any airplane, particularly any piston powered airplane no matter the certification status.

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14 Responses to When Icing Certification Made Sense

  1. Jim Butler says:

    Good comments Mac. I agree completely. To take this a bit further, not matter how hard you try, you can’t write enough legislation to be a good replacement for common sense.

  2. Bob Chenery says:

    There are old pilots, there are bold pilots. There are no old bold pilots who willingly flew in icing conditions (or thunderstorms).

  3. Bob Chenery says:

    To add to my last comment, let me share a true story about icing and weather.
    Years ago, a USN E-2A Hawkeye was catapulted off of USS BOAT. While climbing to mission altitude the pilots noticed some icing and turned on the anti icing systems.

    All seemed well until, while passing FL180, both turboprops flamed out.

    After swallowing hard, the pilot wisely lowered the nose and attempted several relights.

    Finally, passing through 10,000 ft both engines came back online and once again all was well.

    The cause? Icing in the engine intakes with a nose high attitude.

    The lesson? Don’t fly in icing conditions.

  4. Bill Tomlinson says:

    Anyone remember a fellow named Don Jontz? (Not sure if I spelled that right; could be Jonz.) He was an Alaskan bush pilot who wrote a most erudite article about ice flying for “Flying” magazine.

    Two weeks later he was killed in an icing accident.

    His passengers, also killed, included a senator or congressman (forget which) and that triggered the legal requirement for ELT’s [Electronic Location Transmitters].

    • William McIntosh says:

      Don Jonz’s October, 1972, article for “Flying” magazine, “Ice Without Fear,” remains, in my opinion, the finest article ever written on piloting an airplane. In the article, written in an engaging, entertaining style with plenty of personal anecdotes to illustrate his points, Jonz wrote, “Never take off into obviously bad conditions.” That he ignored his own rule in the accident flight of the Cessna 310 east of Anchorage that killed himself and Congressmen Hale Boggs and Nick Begic and a congressional aide, does not negate the validity of his advice in the article. He never advocated remaining in icing conditions , but did call for the pilot to use his head and know his own and the airplane’s limitations “without fear.”

      Over the years , Jonz has been pilloried as falling foolish victim to icing conditions, but in fact, since the wreckage was never found, we do not know if icing was the culprit.

      Safety marches on. Just as Jonz’s accident triggered Emergency Locator Transmitters, perhaps the disappearance of the Malaysian airliner will bring on a requirement for GPS burst transmissions…we’ll see.

      • Bill Tomlinson says:

        I totally agree about the quality of Don’s article. (In fact, I missed that issue of “Flying” so, some years later, went out and bought a whole compendium of “Flying” articles, just so I could have that one!). IMHO he knew more about ice flying than anybody else ever.

        I particularly liked his comment that he had a cheap thermometer attached to his wing-strut with duct-tape – and considered that to be more useful than the half-million-bucks worth of de-icing equipment on a Boeing’s wings!

        I have never considered Jonz to be foolish, but rather have taken the incident as a salutary warning that sometimes Mother Nature throws up problems that are beyond even the best of us.

        • William McIntosh says:

          Your comments land right on the numbers, Bill…it amazed me later how many took Don’s words literally, without applying any imagination whatsoever to glean the larger lessons he was trying to pass on about icing conditions. Those folks (and you know who they were) seemed to gain some sort of vindication from Jonz’s accident to justify their own colorless and stale aviation writing. They seemed to forget the closing words of the article, “…be brave. Carefully.

          Now, if I could only find a reprint…..

          • Chris Conte says:

            I flew in Don Jonz Cessna 310 before he went missing. I’m sure some pilots didn’t understand Don’s style of writing. I have a unpublished article Don wrote in mid 1972. The article was put away and forgotten in Oct 72. To both Bill’s. I think you two would enjoy the article and remember his style of writing. The event he’s writing about might surprise you.

  5. David says:

    Mac is an old fashioned and his articles make it clear that he doesn’t like FIKI, glass panels, airframe parachute systems, composites, modern battery chemistry, etc. Not long ago, folks like Mac resisted the introduction of seatbelts. Pressurized airplanes were ticking time bombs. Mono-wing airplanes could never be strong enough. IFR was a hopeless new gimmick. A hundred years ago, folks like Mac asserted that man had no business flying at all.

    Icing deserves much respect and pilots should be exhibit some caution with any new technology. Mac wants to live in the 1930′s but I prefer to move forward… cautiously.

    • Michael says:

      I have to disagree with the last statement. If Mac is old fashioned, why has he upgraded his panel? Why did he write articles praising the advancements that Gulfstream made with the planeview system and the controller for that system? I feel that the previous comment was made by someone who has never read one of Mac’s articles. If he had, he would know that Mac calls it as he sees it. This is not about being old fashioned. It is about being realistic.

      • Jaxs says:

        That’s correct. He recently called for stick shakers in light planes. He also wrote about the need to invest in new avionics on a regular basis.

  6. Floyd Richey says:

    I flew a C421 that had all the equipment and handled ice well. When Cessna certified the next years model for “known icing”, but didn’t include its previous models it just gives us old timers a lack of respect for the bureaucrats.

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