[Peetwo]

As requested and required, a few of our 'older' associates read and considered the report from ATSB - (above) with a view toward prevention of a repeat performance. One of the more interesting elements discussed was 'Australian Ice' as opposed to it's northern hemisphere counter part.

In essence, it is the same stuff and it's affects on aircraft performance identical, no matter where you pick it up. A known killer, the world over. The difference lays in 'where' it is encountered; and in what season the operation is conducted.

Mid November in Australia is almost 'summer' while in the northern hemisphere it is late Autumn - verging on winter. So, for example a turbine engine and airframe operating in Oz can base performance expectations on ISA + 10° C at MSL; in the USA ISA -5° C is a fair expectation (ballpark). Freezing levels respectively 15 ° C apart, which places the 'alert zone' considerably lower in the northern lands; which is an advantage to performance and an earlier escape from the icing layer. Mind you, I've had ice accretion in temperatures as high as +5 and as low as -25, it all depends on what weather type you are operating in, and where. Our man in the 210 would be somewhere near enough 'max power' at F180 and was dragging some ice around with him; between 'cloud layers'. Can anyone spot the danger areas in this scenario? There are just a few large red flags waving.

Options - climb out of the icing. In theory worth a shot - provided the horsepower available will carry the aircraft through a climb with an iced airframe, already performance degraded (no de-ice boots); and, that there is guarantee of clear air above a 'layered' sky; and, that the ice accumulation does not impact on TAS which leads to a fuel/range problem. - So, having accumulated some ice on the initial climb - and 'topping' the cloud not an option, the next option is 'down' - back through the icing layers - down low enough to shake off the ice. You know there is ice down there - probably have some idea of where you began to pick it up - so why not leave the 'heat' on until you are below that level? So, you descend and arrive at a lower level with double the original ice - and a reduced TAS/range problem, at least until until the ice obligingly disappears. But will it? Here we meet Murphy - always present. 

But what of the airframe performance? Ice weighs - ice disturbs the airflow - ice costs speed and fuel - ice tends to cling in areas not visible - in short, carting ice about the place is at the high end of the risk scale.

One of the more potential serious risks in 'warm' lands is the height at which the arbitrary 'Freezing level' is found. Often toward the top end of turbine power available; but the 'freezing level' ain't the problem is it. The FL simply defines what? The problem area is the icing layers above that - the red zone - where layers merge and mix; where convective currents spread cooled water particles which are quite happy to turn into ice with a small nudge from an airframe. Ice has a habit of 'building' which affects airflow, and allows more area to be presented, degrading speed which allows even more build up - and so begins the chain of events which lead to the hole in that famous cheese reserved for those who failed to have a clear plan and focus on the insidious 'ice-man' who rides with Murphy. 

The slick answer is 'if you get into ice - get out of it' - The sensible, thinking pilot's answer should be .................? Handing over..

Addendum - Flight Safety Detectives : Episode 95 

Icing Issues General Aviation Pilots Need to Know – Episode 95

Several accidents caused by icing reveal safety information that pilots need to know. As we head into a time when icing can be common, John, Greg and Todd want to be sure everyone avoids the mistakes other pilots have made.

“Icing has greater impact on general aviation aircraft than commercial planes. It is important to be prepared for icing incidents,” Greg says.

In this episode the Flight Safety Detectives focus on one general aviation icing event and relate it to lessons learned from other accidents involving icing. The takeaways benefit all pilots. They dig beyond the stated NTSB findings to highlight how pilots need to prepare for icing and how to manage the situation.

Included is a discussion of the TKS Weeping Wing system. They cover the benefits as well as the shortcomings.

Knowledge is power, and the Flight Safety Detectives want to empower every pilot with the latest insights on how to deal with icing as well as the details of relevant safety regulations.

MTF...P2