will this fly?

"Dan Thompson" wrote
"I tend to think this IS a sound argument" This is about the flimsiest
"argument" I've ever seen written, that additional safety equipment, on
balance, makes people less safe because they become more cavalier about
taking risks. It assumes that the people involved are not intelligent
enough to understand the scope of safety benefit and risk reduction being
provided.

That is EXACTLY the assumption, and in my experience it's a pretty
good one for most people.

When ABS came out, many insurance companies would give you a break for
having it. This is no longer the case. Turns out the accident rate
for ABS-equipped cars is no lower than it is for cars not so equipped.
It's not because the system doesn't work - unlike the CAPS
installation in the Cirrus, ABS is proven and reliable. However, it
causes people to drive more agressively, thus nulling out the benefit.

Asessing the safety benefit of a given feature is not trivial, and
this is especially true if the feature is high tech. For example,
your asessment of the safety benefit of CAPS as a backup to the TKS
reveals a lack of understanding of the scope of safety benefit and
risk reduction being provided.

The TKS system is, in fact, a tremendous safety advantage in icing
conditions. The fact that it lacks known ice certification does not
mean it offers no protection (or even reduced protection) but that the
level of protection it offers is not proven. Nonetheless, the system
is well understood, and the Cirrus TKS installation is not much
different than what is seen on similar performance airplanes which are
KI. The level of protection is not proven, but it can be reasonably
estimated. I, too, would be willing to undertake flights with TKS
(even if not certified KI) that would ground me in an airplane with no
ice capability. However, the parachute is not a player here.

If the icing is sufficiently bad that the TKS system is overwhelmed
and the parachute system must be used, there are several reasons to
believe that the outcome will be less than wonderful.

First off, the parachute may fail to deploy properly. If there's
enough ice formation on the wings to overwhelm the TKS, how much will
there be on the fuselage? The deployment system literally has the
risers peeling away thin layers of fiberglass from the fuselage, and
the deployment system is sufficiently powerful to do this. Will it
still be powerful enough if it has to go through layers of ice as
well, or will it remain in trail - causing what skydivers call a bag
lock? Will the risers be damaged in the process, only to fail upon
opening shock? Nobody knows; the situation has not been tested or
even mathematically modeled.

If the parachute does deploy, it WILL accumulate ice. Anyone who has
ever skydived in the North in Winter will tell you that. In fact, the
slow-moving, small-diameter multiple suspension lines are ideal for
accumulating ice. Round parachutes really don't flex much unless they
are steered - something the Cirrus installation does not allow - and
will not be effective in shedding ice. Further, the fuselage will
already have accumulated ice, and will simply keep accumulating it.
Therefore, you can expect that by the time impact occurs, the plane
will be well over gross due to the ice. At gross weight, the descent
rate under parachute is already very high. In the overgross
condition, it will likely be high enough to injure the passengers
(which, at this point, includes everyone in the cabin since the pilot
ceases to have any ability to influence the flight once the parachute
deploys). I have to wonder what the survival prognosis would be in
this case.

Michael