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Re: Split switches

Subject: Re: Split switches
From: Robert L. Nuckolls III <nuckolls@aeroelectric.com>
Date: Wed, 2 Feb 2000 08:00:09
 <3.0.6.32.20000201231924.008d04b0@aeroelectric.com>


>Bob, Regarding your idea that the switches should match. . . I would suggest
>that there are some switches in the cockpit that should not match, and I
>think the master/alt switch is one of them. When I look at the overhead
>panel of the MD80 I fly at work, I see a myriad of different switch types.
>Some twist, some toggle, some have round heads, some flat. A couple even
>have a little row of "landing lights" fixed to their toggle.  All this is
>done for a reason. . . To help differentiate one from another at a glance.
>Now the Kitfox certainly has fewer switches to worry about, but I would
>argue that the MASTER switch should stand out (maybe this is why Cessna and
>Piper paint it red). Whether it's because I want to shut everything down
>quickly prior to a deadstick landing, or just to have it stand out in hopes
>that I don't walk off and leave it on (never happened to me personally, but
>I've heard. . . ), I see no reason, aesthetics aside, it should look like
>the others.
>
>Okay, I guess I could paint your switch red, but I still think mine looks
>pretty cool.

   Inadvertent switch operation is a factor we'll be addressing
   in the latest chapter to the book which I'm writing now. The
   easiest way to deal with this is in panel layout. Consider
   a single row of switches with a layout like l-mag, r-mag/start,
   dc power master, alt field breaker, e-bus alt feed (or aux
   dc power master, aux alt field breaker (if used) fuel boost/prime, 
   pitot heat, landing/taxi lts, nav lights, strobes.

   When one is interested in killing everything in a hurry, the
   ship is made cold with the switches at the far left. Switches
   at the right are grouped in order of operation. Strobes on
   first. If it's dark, nav lites next, other exterior lights
   next. There's a buffer between power control switches and
   appliance switches with controls where inadvertent selection
   doesn't represent an immediate concern.

   One can put little plastic booties over switches to color
   code them.  The recomendation for "sameness" is driven by 
   several considerations. Low cost, ease of replacment (one
   nut and a few fast-ons), ease of initial fabrication,
   mutliple suppliers for the same switch.  I'm trying to
   break the old paradigms where we EXPECT things on airplanes
   to be expensive to buy (unique, unsubstitutable, type 
   certificated), expensive to replace (only your friendly $40/hr
   certified wrench twister is allowed to do it), and carved
   in stone by traditional-flyer-think that starts with
   us as pilots and becomes more viscous as you move up the
   ladder toward Jane Garvey's office.

   One of the reasons that the future of single engine airplanes
   is so bright is that amateur built aircraft already dominate
   the modern fleet and will soon dominate the total fleet.
   We can only improve on that by increasing people's comfort
   level with application of critical review to their own airplane
   based on how they plan to use it and without the "assistance"
   of government or traditionalists. Split-second, bad decision
   scenarios exaserbated by panel ergonomics has always been
   a heavy tool wielded by doom-sayers amoungst us. In fact,
   the vast majority of injury and death in airplanes comes from
   poor pilotage followed by sudden onset of situations from
   which there is no escape. The numbers of folk that met
   their demise cause they hit the wrong switch while on
   short final to a big rock are, I suggest, very tiny if
   indeed they even exist.

   Which brings up another point I've been pondering with
   respect to crashworthiness. An engineer I work with at
   Raytheon used to do accident investigations. He noted in
   passing one day that airplanes in which the battery
   was NOT ejected from the wreckage often caught fire.
   Not once in his experiece did he see an airplane burn
   if the battery was thrown out from the wreckage. We got
   to talking about a g-switch in the battery master contactor
   control circuit. Then I asked him, had the airplanes
   NOT burned, was the crash such that anyone MIGHT have
   gotten out.  He thought for a time and said "no."

   When you hit the mountainside, pull the wings off, 
   ice-up and stall, run out of gas, or hit another airplnae,
   I'll suggest that the position of your switches when 
   you hit the ground is insignificant. We are in far
   greater danger from failures of pilot judgment,
   inattention and skills than from anything mechanical 
   or ergonomic. 


       Bob . . .

     --------------------------------------------
     ( The only time you don't fail is the last ) 
     ( time you try something, and it works.    )
     ( One fails forward toward success.        )
     (                     C.F. Kettering       )
     --------------------------------------------
       http://www.aeroelectric.com



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