AVmail: September 16, 2013

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Letter of the Week:
Factoring Human Factors

I was interested in the article on the KSN770 published in the Sept. 13 AVwebFlash, in which it states that "graybeards may still prefer [to use] a transfer key" as opposed to using touchscreen controls.  I'm not a graybeard (is there a politically-correct term for female pilots, too?), but I am a human-factors engineer, and I'm always amazed at the proliferation of touchscreen and data-entry techniques in today's avionics.

For example, the first time I flew in a plane with a "digital" transponder (i.e., one with pushbuttons for the digits rather than the old-fashioned rotary knobs), I thought this was a great idea.  It would be much faster to enter four digits rather than twist a knob four times.  And I thought it was cool to have a specific "VFR" button to change the squawk to 1200.

But then, as I was flying in IMC in moderate turbulence, I got a request from ATC to change my squawk.  I couldn't stabilize my hand to hit the right buttons to get the squawk entered in.  My hand was bouncing along with the plane.  Eventually, I was able to enter the squawk, but it took me quite a long time.  And this is a simple operation, and fortunately one that's not intended to occur all that often.

Consider modern MFDs.  I look at the "soft keys" surrounding the screen and have to laugh.  When I design objects for military and other government systems, I'm required to comply with MIL-STD-1472 human factors designs.  Among other things, these call for all buttons to be at least three quarters of an inch wide.  Some of the MFD buttons are less than half this width, and are separated by only a few millimeters.  How is someone supposed to hit the right button while in turbulence?

My experience with the (poor) avionics human factors design has caused me to make modifications in my own designs:  I include a "perch" for the user to hold onto when selecting a button or a touch-screen to better enable them to accurately enter information in turbulence, whether that turbulence is due to air currents or bouncing down the road in an HMMWV.

But I still wish the avionics companies would hire some good human factors engineers rather than designing stuff that is flashy and looks cool!

Shelley Rosenbaum Lipman

G100UL Is Ready

Thomas Yarsley expressed concern about Embry-Riddle's fuel testing program using G100UL.  Tornado Alley Turbo has been running this fuel in a turbonormalized IO-550 for a couple of years now.  They carry 100LL in one tank and G100UL in the other so the engine monitor can show any differences.

G100UL appears to be a true replacement for 100LL.  It can be made in any refinery, does not require a dedicated delivery system (no lead), and can be mixed in any proportion with 100LL with no ill effects.  The goal is to have it STC'd for a wide range of high-performance engines no later than 2014.

Paul Hekman

Scud Running Memories

I loved your article on scud running.  I purchased a Super Cruiser in 1994 and learned to fly it in Ireland.  I was taught by a crusty old instructor, and scud running was on the syllabus.  About a month before my flight test, with about 50 hours under my belt, I was sent on a solo 80-nm cross country with 800-ft. cloud base and three to four miles visibility.  Every lesson contained in your story was briefed before departure.  It was a very smooth flight.

After getting my test, I was quite a competent scud runner.  Like Hack, I'd usually only do it if the visibility was good (six to eight miles), and if it wasn't, it had to be very stable air.  Ireland is small, so I knew my way around extremely well.  Despite having a GPS, I'd always have a map open and keep my finger on my location on the map.

I've only scud run once in the U.S., following a colleague in close formation through a part of the world he knew well.  Eventually the weather became too low for me, and I just put down in a farmer's field.  He proceeded on.  It helped that I was flying a Cub.

I totally agree that scud running has become very dangerous.  Last time I was in Ireland, wind turbines and cell phone towers were everywhere.  It's just not safe to do it any more.

I really liked the trip down memory lane.

Serena Ryan

No Place for Politics

Rick Durden says "the best piece of legislation ever to pass Congress over the determined opposition of Republicans, the G.I. Bill of Rights."  In fact, Harry W. Colmery, a former Republican national chairman, is credited with writing the first draft of the G.I. Bill.  Furthermore, Edith Nourse Rogers, R-Massachussets, helped write and co-sponsored the bill.  It is true that over the years, Republicans have opposed some amendments.  But Durden's characterization is inaccurate and offensive.  You should publish a retraction immediately.

Geoffrey Beale

AVweb responds:

It was indeed Harry Colmery who came up with first draft of the G.I. Bill introduced in the House on January 10, 1944.  In 1984, it was revamped by Democrat "Sonny" Montgomery, and that revision became the Montgomery G.I. Bill.

And while this information might be interesting, it has nothing to do with scud running, which was the topic of the article.  It should have been edited out.