Warringah
Radio Control
Society
Incorporated
(Incorporated under the
Association Incorporation Act 1984)
by Dean Riebolge
We all know of those incidents
or close calls at the club that seem to happen in our everyday flying.
Sometimes we’re the only ones that know (its happened to us and no-one
else saw it), sometimes we observe something that’s happened to others
(they may not even be aware of it). Most of us usually either move on and
forget, maybe putting it down to a ‘one off’, or filing it away as
another learning for future reference which builds up our experience as
modellers. Sometimes, and best of all, we share the learning with others
on the spot in a respectful and appropriate way.
The committee has asked me to start
a, regular, column titled "Near Miss". It's intended to be a forum
where we can have club members share any experience or learning that they
feel will benefit other club members. This can be related to a flying incident,
use of equipment or behaviour. You may have observed this happening to
someone else or its happened directly to you.
The intent of the "Near Miss"
column is similar to Safety Warnings or Incident Reports that many businesses
now have as part of their internal O&S systems. They are a proven way
of sharing learnings and changing behaviours and attitudes.
All submissions will be treated confidentiality
with no names mentioned in the "Near Miss" report. The focus will
be on what can be learnt rather than on who is to blame or who didn't do
what.
#1 (September 2006):
Imagine it …. a group of members are in
one of the sheds getting their electric models ready to fly. Someone comes
along to greet them and ‘check out’ the proceedings. Modeller gets up from
his work …about to have a chat then …. Holy Cow! ... the engine starts
up, goes to full throttle and the model takes off and starts doing tight
circles around one of the setup tables … MAYHEM … CHAOS … SHOUTS … SCREAMS
…. until one particularly althletic member (who will remain nameless)
jumps on the thing, problem solved …. sort of. This may sound funny in
retropsect but its bad news. So what are the learnings?:
1
|
Electrics, once armed by connecting power
onto the electronic Escape (which governs throttle control) are ARMED and
LIVE beasts. Treat and handle your plane on the assumption it could power
on AT ANY TIME. Maintain a hold of your aircraft AT ALL TIMES when it is
armed as they could start based on some other input other than the transmitter
(read the warnings on your electric escape). NEVER leave an armed electric
UNATTENDED ANYWHERE. Experienced and top notch electric flyers in competitions
live by this rule, so should we. |
| 2
|
Sometimes the magic of electric silent
flight can just lead us astray by letting us think the normal way we do
things still applies ….ie you turn your tranny on and the Escapes on but
its not REALLY on is it ?, after all the motors not spinning at a slow
idle like my Glo motor is it ?, if the props not moving then its actually
off …and I can get back to it when I’m ready can’t I ?……WRONG…reread the
above. |
| 3
|
DISCONNECT THE BATTERY CONNECTION to the
Escape at all times when the model is not in use, EVEN if you have an On/Off
switch at the Escape itself. On /off switches can fail and a lot of Escapes
now don’t even have one. With this type of Escape switching off at the
transmitter only, and leaving the battery connected, does not mean the
system is UNARMED….IT IS STILL ARMED….reread the above. |
4
|
For the above reasons electric models
are NOT TREATED AS SOME SORT OF EXCEPTION to club rules just because
they don’t make noise and throw goo out. Not only should they not be left
armed and unattended but THEY CANNOT BE STARTED in the sheds or in
the spectator area either. Just because they do not make any noise, or
the propeller IS SMALLER does not mean that the spinning propeller ( usually
rotating at a lot faster revs than in Glo motors) causes any less damage
to yours or someone else's person. All types of motors cannot be started
in these areas…START and CHECK your motor in the pits area. |
So, some good wake up calls around electric
flying from the above ( I must admit I have been guilty of one of the above).
Especially so, as from my observations and at the rate of progress in batteries
and motors I PREDICT that within five years everyone flying a 60/90 size
model or below will make the switch to electrics…….now that’s a discussion
item ! |
#2 (November 2006):
Now hold on tight one and all as, for
this Near Miss report, we try and not slide into some magical technical
‘swamps’. As a ‘techno vegetable’ I don’t intend, nor am able, to get into
the technical detail on this one. However I will try and highlight some
risks that we face with our transmitters…. and their transmissions! …and
what we could do.
Some recent discussions at the field between
members has centred around the apparent ability for a transmitter (say
taken out with its owner to the runway whilst they pick up their disabled
plane) to swamp or override the signal of a transmitter located at the
Pilots Flight line and thus leading to the inevitable. This even though
the two transmitters are different or widely spaced frequencies. I must
admit that, upon hearing of this I was somewhat sceptical. Wishing to discuss
it at a recent committee meeting I rang a couple of experts in the field
to get some facts (I have not had time to ask their permission so won’t
use their names but rest assured they are TOP NOTCH especially when it
comes to radio gear related to our hobby).
Yes I was surprised, for both agreed the
above effect, known as ‘third level intermodulation’ was well known and
understood and could pose a risk in a situation as described above. The
transmitter closest to the receiver (even if that receiver is in a flying
aircraft) could override/swamp the other frequency. Crikey I thought, what
a can of worms, where does it stop, what about walking out to taxied aircraft,
walking with trannie in the start up area, range checking etc…aaagh more
regulations!
Wait on and calm down, as always there
is a balance between the technically possible and what is probable. Whether
this phenomena occurs is, apparently, subject to a variety of variables….
is the aerial fully up, part up or down, which direction is it pointing
in, whats the distance between the trannies, distance to the receiver,
what are their brands and age, how many are transmitting and so on. One
of the experts indicated that as a precaution one should ensure that the
trannie aerial is down when walking onto the field the other said
the greater danger was being on the field and active runway itself!
The Committee discussion really centred
on the balance between what is probable, what was the real life history
(not just at WRCS) of this happening, the consequences and the effectiveness
of any regulation. There was general agreement that we could not and should
not regulate for this due to the inherent combination of factors present.
The only real prevention would be to have one transmitter on at a time,
great!
As in many other areas of life a balanced
assessment of the risks and an acceptance of some degree of risk is needed.
However it was felt that the subject should be taken up in the Near Miss
report so as to raise everyone’s awareness.
Good practise (not to mention respect
for your fellow club members and your own investment) seems to suggest
that we all be aware of this effect and if we have to walk out to the runway,
for whatever reason, do so with the trannie aerial down please…better still…
leave it at the flight line, preferably with someone ready to switch off
at your signal…. this has the added bonus of leaving your hands free for
the task at hand and keeping friendships intact!
Finally there were two more learnings
from the above discussions that we should consider,.
Interestingly, whilst chatting to the
above gentlemen both were unanimous in considering that the single biggest,
most likely to occur, ‘actually has occurred’ risk when using transmitters…is….
CROSSING AERIALS, i.e. when pilots are standing next to each other on flight
lines. VERY HIGH probability that this will spoil both pilots day and cause
loss, tears, angst or worse. VERY GOOD PRACTISE to try and stand a minimum
of two (2) metres from each other and use discipline in not physically
following the plane across with your body and therefore have the transmitter
aerial describe an arc, cross over and…..well you can guess.
Oh!, and the second learning, well that’s
another interesting one for us to ponder….that is, just because something
is not a rule or regulation doesn’t mean that its not right….or the right
thing to do |
#3 (April 2007):
I wanted to start this Near Miss with
some smart, piffy comment about the philosophy of cause and effect. If
I can put a couple of good examples as a lead in, I thought, people would
much more quickly grasp my real intent. Off I go and do a web search on
“cause and effect” straight into Wikipedia and this is what I get:
| “If x is a necessary cause of y; then
the presence of y necessarily implies the presence of x. The presence of
x, however, does not imply that y will occur.” |
How about this one:
| “If x is a sufficient cause of y, then
the presence of x necessarily implies the presence of y. However, another
cause z may alternatively cause y. Thus the presence of y does not imply
the presence of x.” |
Mmmmm…bugger…all I’ve done is confuse myself.
So let me take the simple approach. At last year's October Scale Day the
crash of an electric model prompted a Board of Enquiry to be set up to
investigate the cause/s of the crash. Why? Two reasons, firstly the plane
overflew the car park on its way down narrowly missing some cars (but more
importantly a couple of young kids playing in the car park…thus being serious
enough to warrant an Enquiry) and secondly, one of the main reasons we
set up any Enquiry is so we can all share learning’s from an incident in
an effort to stop it happening again.
What made this incident interesting is
that the conclusion was reached that no one could actually determine the
cause which led to the effect (i.e. a plane crashed !).
In fact there may have been any of a number
of possible causes ranging from the weather, receiver glitches, frequency
interference, or even contingent causes (e.g. a previous hard landing)
may have caused something else which then caused the effect….I know I know
…Wikepedias got to me.
This is a bit of a shock to me and maybe
to you….we should always know cause and effect… isn’t that how the world
runs…how are we supposed to learn anything if this doesn’t apply….this
is more serious than a mere model crash….back to Wikepedia…and yes here
is the answer…
| “...it may be impossible to know that
certain laws of cause and effect always apply - no matter how many times
one observes them occurring. …. the best that we can do is to maintain
an open mind and never presume that we know any laws of causality for certain.
“ |
Now before I go any further let me state that
I’m definitely not saying/implying that the pilot in this case tried to
save the plane above all else, it’s very doubtful he had any control at
all.
What I am saying though, is that, sometimes
when you look back at things you can’t piece together what actually happened
and what caused what.
All that you are left with is the
fact that we know a plane is going to crash, regardless, and sometimes
the only safe thing to do is….DUMP IT…FLY IT INTO THE GROUND, GET IT AWAY
FROM WHERE IT CAN CREATE AN EVEN BIGGER PROBLEM.
This is hard, counter instinctive….for
me at least… I LOVE my models….how can I fly them into the ground?
It’s a bit like the stories we hear about
the full size pilot steering his crippled plane clear of a built up area
no matter what the personal consequence.
So here follows the real message and learning
from this inquiry:
| …. sometimes knowing what caused a
crash doesn’t matter, there is no learning, sometimes the only thing that
matters is managing the effect…..what we did when its on the way down and
what we did to minimise the effect….regardless of what it means to us personally. |
|
Ciao Dino
|