Return-Path: Sender: (Marvin Kaye) To: lml@lancaironline.net Date: Sat, 11 Oct 2003 22:50:00 -0400 Message-ID: X-Original-Return-Path: Received: from cepheus.email.starband.net ([148.78.247.123] verified) by logan.com (CommuniGate Pro SMTP 4.1.5) with ESMTP id 2633154 for lml@lancaironline.net; Sat, 11 Oct 2003 18:29:04 -0400 Received: from regandesigns.com (vsat-148-63-101-227.c002.t7.mrt.starband.net [148.63.101.227]) by cepheus.email.starband.net (8.12.9/8.12.9) with ESMTP id h9BMTNqi013597; Sat, 11 Oct 2003 18:29:27 -0400 X-Original-Message-ID: <3F88841E.6020703@regandesigns.com> Disposition-Notification-To: Brent Regan X-Original-Date: Sat, 11 Oct 2003 15:28:46 -0700 From: Brent Regan User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.0.2) Gecko/20021120 Netscape/7.01 X-Accept-Language: en-us, en MIME-Version: 1.0 X-Original-To: Lancair Subject: Of Men and EFIS Content-Type: text/html; charset=us-ascii Content-Transfer-Encoding: 7bit The myth of VFR Synthetic Vision.

There is a visceral and compelling attraction to panel glass. Something about the tech look, the bright colors or the perceived superiority makes pilots drool and lust to fly behind same. The manifestation of this lust is a sometimes irrational desire and a willingness to lay aside logic and critical thinking. No wonder airplanes are traditionally identified as female since they stimulate those same, ancient neural pathways.

Before I continue and for those not already aware, I am one of the four lead engineers that created the CFS EFIS 2000 and the certified CFS Flight Logic EFIS systems so my opinions are not to be trusted. I am a lowly, money grubbing fool who's only objective is to destroy the fine work of brilliant engineers. At least that is how some competitors describe me ;-) .

Why EFIS? Simple. Positional Awareness. Where am I? Where am I going? How do I get there? All question that need to be answered in real time with a maximum of gross accuracy and a minimum of effort. Some of this information (e.g. attitude) needs to be accurate on a time scale of seconds while some (e.g. flight path to destination) needs to be accurate on a scale of minutes. All are critical to the success of the flight. Success being defined as being alive after getting to where you were going.

In a traditional, steam gauge IFR environment the pilot takes abstract symbolic information (needles and numbers) and mentally constructs a three dimensional "picture" of the dynamic status of the airplane. This picture has 18 degrees of freedom. They are; latitude, longitude, altitude, horizontal velocity, horizontal acceleration, vertical velocity, vertical acceleration, lateral velocity, lateral acceleration, roll angle, roll rate, roll acceleration, pitch angle, pitch rate, pitch acceleration, yaw angle, yaw rate and yaw acceleration. Phewwww! Some of the important ones like altitude, horizontal velocity, vertical velocity, pitch angle, roll angle and yaw angle (aka heading) have direct reading indicators, some are indirect (e.g. Slip Indicator) and some combine information, localizer / glideslope for example. All this must be managed by the pilot to produce a series of control inputs (roll, pitch, yaw and power) while doing all the other things that are needed for flight (engine management, communication etc.). It is notable that our brains did not evolve specifically to meet these challenges. Fortunately, bipedal locomotion gave us the balance and planning skills needed for flight.

All this mental gymnastics consumes a significant portion of your available brain power so anything that makes things easier would be a good thing. Enter the microprocessor, champion of the mundane, repetitive task. Who would ever have thought that you could pass lightning through glass and get computers. So what did the avionics engineers do with this marvel of engineering? They made electronic versions of steam gauges and, like the first digital watches, they replaced a reliable, mature, and inexpensive technology with less reliable prototypes of lower performance...but they cost 50 times more.

Only when electronic gauges become more reliable and cheaper than their mechanical forebears should they directly displace the latter.

Electronic devices are fantastically complex. Their apparent reliability and simplicity are the product of thousands of engineers working for millions (billions) of hours designing the raw materials, subsystems and assemblies and then teaching them the language of on and off. This complexity leads to adaptability and can be harnessed to simplify the demands on our biological, non upgradable computers.

The "outside the box" guys concluded that rather than imitating mechanical gauges it would be better to rethink the whole user interface to make life in the cockpit less demanding. Synthetic Vision (what I would see without the clouds), Velocity Vectors (what direction am I going), Highway in the Sky (how do I get there) and Terrain Avoidance (dodging the cumulous granite) are the products and, like the computer GUI and mouse, these ideas were quickly adopted. Any respectable engineer can now buy off the shelf hardware, write a bunch of code and brew up an EFIS demo that would make Linberg pee his jodhpurs. Once the path is cleared, building an EFIS demo is not a terribly difficult task. This was evidenced by the plethora of glass at OSH. Making that product reliable in the flight environment turns out to be the real trick.

For want of a nail the shoe was lost. For want of a shoe the horse was lost. For want of a horse the battle was lost. For want of a battle the war was lost. For want of a war the King was lost. The message is that the details matter, sometimes more than the big ideas. As in building an airplane, building an EFIS that looks good on the ground is 90% of the task and finishing it so it will operate and survive in use is the other 98%.

Certification, in part, is the process by which a device is tested to show that it conforms to certain minimum standards of performance established for avionics. In order to pass those tests the device must be designed to pass them. Commercial and even industrial components are not designed to pass tests intended for avionics. The tests are divided into categories (Vibration, Shock, Lightning, Noise etc.) and levels depending on application. For example, helicopter vibration test levels are 10 times higher than turbine aircraft levels. Some tests can be conducted on a device installed in a specific airframe or, at a higher level, stand alone. The lightning test is a good example. One way is to install the device in an airframe and then shock the airframe. The device in now ONLY certified in that particular airplane with that exact mounting and wiring. Any change may require a re-test. Stand alone testing requires that each and every pin on the back of the device receive a 600+ volt, several hundred amp shock several times and live. This is why some certified EFIS systems fail when installed in composite airframes. The protection provided by the certified airframe was not present in the new installation and so a little P-static had it's CPU for lunch. Ouch.

Bottom line is that most experimental EFIS systems use commercial computers and automotive sensors. Designing a purpose built processor board takes a lot of time, money and talent and is hard to justify when you can buy one for a couple of hundred bucks. The bad news is that commercial Single Board Computers don't much like the flight environment will go tango uniform in short order. Having "been there, done that" I can tell you this from direct experience.

As it turns out the CFS EFIS 2000 was originally designed to be a certified system and many of the certification test were performed on, and subsequent modifications were made to the system. The Flight Logic System was a redesigned evolution of the EFIS 2000 because of the Capstone requirement to fit the display into a 6.25" wide radio rack. For this reason the EFIS 2000 is the only known "certifiable" experimental EFIS on the market.

At the latest Lancair Fly In I brought the "Paint Shaker" made famous in the CFS video and offered to do a head to head test. Blue Mountain was a no show and OP quickly declined as it would void the warranty.

"So what. I understand it is an experimental system. I'll just fly VFR." you say. To which I reply "Then why spend the money at all?". If you really only fly VFR then a synthetic vision system is a waste of money as you already have a better vision system that is free. It is called a windshield and it is something you should be looking out of rather than fixating on the pretty colored display. Navigation and moving map functions can easily be handled by a Garmin 530 or similar.

"I'll use traditional gauges as backup when I fly an experimental EFIS in IFR" you say. IMHO, this is a really bad idea for reasons of interference and pilot disorientation. Commercial computers and LCD displays emit all kinds of radio interference. These emissions can and do interfere or block COM, NAV and GPS signals. This is one or the reasons why your laptop needs to be turned off during takeoff and landing on a commercial flight. Laptops are not tested to see if they interfere with navigation equipment. Has the experimental EFIS you are considering been tested?

Pilot disorientation is not something you would expect from a synthetic vision display but it becomes a real problem when the picture does not match reality. As I mentioned before, big color displays are compelling, especially the more realistic ones. If the AHRS starts to tumble (due to an iced pitot tube, for example) your brain WANTS to follow the picture and not that ugly little standby attitude indicator. The best thing to do in this case is turn the EFIS (and it's autopilot) off and try to remember how to fly the standby gauges. Expect to use your Unusual Attitude Recovery skills.

Remember that the things that are most likely to kill most EFIS systems (shock, vibration, electrical discharge, pitot icing) are the most often found in IFR conditions. In other words, it is most likely to fail when you need it the most.

Of course, there are things that will kill a computer that most engineers never considered. Take neutron radiation for example. When one of these energetic particles decays in a computer's RAM it may cause a bit to flip which, like the lost nail, can bring the entire system down UNLESS Error Correcting Code (ECC) RAM is implemented. This is one of the reasons that high reliability network servers always have ECC RAM. Now, granted, the effect is small (7E-13 SEUs/bit/hour) on the ground but in the flight levels the radiation levels are orders of magnitude higher an so an event every few hours should be expected. Does your experimental EFIS have ECC RAM?

More Information at: http://www.boeing.com/assocproducts/radiationlab/publications/Single-Event_Effects_in_Avionics.pdf

Quick Quiz:
What is the job with the highest radiation exposure (mRAD/Year)? X-Ray Technician? Nope. Nuclear Power Plant Worker? Nope. Try Flight Attendant. They get a higher dose than pilots because the cockpit has thicker walls and better shielding.

In conclusion I would offer the following:

If you only plan to fly VFR then you don't need Synthetic Vision, Terrain Avoidance or Highway in the Sky.

If you fly IFR then you need an EFIS that can pass the DO160 Certification Tests because a failed EFIS is worse than no EFIS at all.

There is a world of difference between "We haven't noticed and problems." and "We have exhaustively tested the system and passed the requirements for certification and installation in over 600 aircraft types." Any engineer can say they have addressed all the problems but until they try to prove it through testing they won't even know of ALL the problems.

If you can't afford price of quality then you can't afford to throw away half that much on something you don't need or can't use. Follow Kirk's advice and install traditional gauges and a Garmin / UPS moving map. Be patient, the prices will come down and you can always spend the money later (once spent, getting it back is problematic).

Remember that the market is full of prevaricators. Kirk's first hand account and Lancair's actions seem to run counter to the BM Press Release.

Consider the future existence of the offering company. Will you be able to get updates and repairs in one year? Ten years?

I haven't even touched on all the things that can go wrong in software.

Your money and your safety are at risk. Be sure of your facts before making a decision and WHATEVER you do, don't listen to me. I am just a lowly, money grubbing fool who's only objective is to destroy the fine work of brilliant engineers.

Regards
Brent Regan