April 1, 1994
By Bruce Landsberg
Build an aircraft the very best you can, then wait five minutes. Someone will pop up with a better idea to improve it. All of us have wished for changes to the airplanes we fly to make them safer, better performers, more comfortable, and more contemporary. The list of better ideas offered here is presented with the greatest respect for those who have actually designed and built something rather than just indulging in Monday-morning quarterbacking. Most of the ideas are not original and have come from various sources. Some are common on business jets and airliners but have not found their way into lighter aircraft because of certification roadblocks or cost factors. Some already exist in the marketplace and should be incorporated into many more aircraft. We have deliberately focused on the simpler things here, with a few exceptions. Lowspeed aerodynamics have been pretty well researched, and there might be some small gains, but most of that magic has already been used up. Convenience and safety go together. The fewer distractions in handling the equipment, the less likely we are to get distracted, which results in a measurable increase in safety. That profound thought has guided the design principles of many recently designed aircraft, but the older ones were built before this logic came into wide use. So, to the manufacturers, the dreamers, the doers, and the certifiers, let's think about how we can improve the future rather than accepting the "facts" as to why we can't.
In jets and cabin-class twins, a whole segment of the instrument panel is dedicated to the proposition that pilots generally do a lousy job of monitoring the gauges. This has been the thinking of auto manufacturers as well. The proliferation of "information centers" on late-model cars attests to the fact that we can easily and inexpensiveIv monitor important items such as oil pressure, engine temperature, open doors, electrical malfunctions, headlights being left on, low fuel, bad brakes, and much more. Some of the light aircraft manufacturers now incorporate this technology into their current production machines, but even then, they sometimes fall short of the mark. Here are my suggestions. Some are nice to have and others are essential, and as always, we have to consider weight, cost, and panel space tradeoffs.
Normal items that should be monitored by a green annunciator include landing/taxi and position lights, picot heat, windshield heat, and heated propellers, if we're fortunate enough to have that kind of equipment. If the selected function fails, the annunciator should flash to alert the pilot. Normal mode annunciations allow the pilot to quickly confirm, without looking for a switch on a typically hidden subpoenal, that a certain function is being performed. How many times have you left the landing lights on for longer than needed after takeoff? If a heated prop fails, wouldn't it be nice to know rather than waiting for the inevitable imbalance and vibration that will come with ice accumulation? Troubleshooting would be much easier.
Fuel pressure and quantity are vital to continued engine operation and should be shown in green or yellow, as appropriate. Electric pumps used for takeoff and landing would be green, and those used just for priming and as a backup to the primary pump should be shown in yellow to confirm their operation.
Low-fuel warning lights should be independent of the fuel gauges and would go a long way to eliminating some of the 190 or so fuel mismanagement accidents we have every year. It wouldn't matter how much fuel the gauge showed or whether the tanks were full or not. You could even ignore the fancy fuel totalizer. Very simply, when the light came on, the pilot would know approximately 15 minutes of fuel remained in that tank. Ignore the warning at your own risk. Maybe that's why some refer to annunciators as "idiot lights." Lights and systems do fail, but the human factor has traditionally been much more unreliable.
Critical functions, such as oil pressure, vacuum system pressure, and electrical system health (ammeter/voltmeter), should be shown in red and should flash when a problem arises. The small needle movement on many existing gauges that signifies the difference between routine operation and potential calamity is hardly attention grabbing. We need to know of a problem sooner rather than later.
A few general comments about annunciators: First, group them in an area of the panel that is close to the normal scan. Second, make sure they are visible even in a bright, sunny cockpit, and, finally, draw attention to a status change by flashing a master warning light or the individual function light until the pilot acknowledges by pushing a button or taking corrective action.
On sophisticated aircraft, there is a check list call-out to the effect that the annunciator panel is clean and green" for takeoff, meaning that there are only normal lights illuminated. It is one last confirmation that the aircraft is ready to fly, that we haven't forgotten a critical item, and that all monitored parameters are in the proper range. These lights don't always prevent catastrophe, but it might help. One key ingredient of annunciator systems is to keep them simple and false alarms to a minimum. The air carrier folks tell many stories of doing battle with nuisance warnings that serve to desensitize rather than warn.
Isn't it amazing that most of the attitude indicators in light aircraft, the center of the instrument scan, don't have a warning flag? I have watched many times in simulators and once for real where pilots happily followed a dead gyro to where the successful outcome of the flight was in serious question. When a gyro fails, it usually takes a few minutes to spin down, and if the pilot is not carefully cross-checking other instruments, it can become a real problem under instrument meteorological or night conditions.
We need more bugs in the cockpit, and I'm not referring to the multilegged or the computer software kind. Bugs are rotatable marks on flight instruments that allow pilots to remind themselves of a particular heading, speed, or altitude. They have been used in every airliner and sophisticated business aircraft since the early 1960s.
The first bug I ever saw was on the heading indicator of a Piper Arrow that had a wing leveler. It was a triangular-shaped pointer that traveled around the circumference of the heading indicator and could be set to select any heading that the wing leveler should fly.
If autopilots and airline pilots need reminders, what about the rest of us?
Airspeed bugs point out the reference speed on climb-out and ap- proach. Most jets have several. How many accidents do we have where airspeed control is a factor? A $3 plastic marker sure couldn't hurt.
The same concept applies to altimeters. I rigged up a poor-man's altitude reminder on a Mooney I flew, using an old thumbwheel switch, and many of us use the rotatable card in the automatic direction finder to remember the assigned altitude. How difficult would it be to build some sort of reminder into an altimeter rather than resorting to an afterthought?
The angle-of-attack (AOA) indicator has been around for decades and is routinely used in high-performance aircraft. It measures the angle of attack directly, unlike the airspeed indicator, and automatically compensates for aircraft weight and G loading in steep turns. It shows the target AOA for climb-out and approach, usually by a needle that drifts toward a red sector of the dial if the AOA approaches the danger zone.
Many serious accidents occur in single-engine fixed-gear aircraft during maneuvering flight, which are frequently ascribed to the pilot's failure to maintain airspeed. Would a good AOA warning system help? I think so, and it should be installed on training aircraft, so pilots begin to understand what AOA really means, particularly in steep banks and pull-outs from dives where the indicated airspeed is well above the normal stall speed.
Some instruments are bigger than they need to be and take up valuable panel space that could be devoted to more useful equipment. Commander is using smaller instruments on its redesigned 114B, and Beech is to be commended for reducing the size of the power instruments on the new 36 Model Bonanzas and 58-series Barons. They gave up very little readability, though the addition of digital displays within the analog gauges would be even more helpful. Why couldn't this be done on other aircraft cost effectively? It makes you wonder.
Good visibility is essential to safety. I enjoy looking at aircraft structure as much as anybody, except when looking for traffic, airports, landmarks, scenery, runway lights, windsocks, etc.
Some airplanes have really good visibility; you know the designers made that a priority. With others, it was obvious that compromises were made, and the cockpit visibility is less satisfactory.
Some early model aircraft had superb visibility, taking into account seating position and general cockpit design. Often, when an aircraft is redesigned, the height of the glareshield is raised to accommodate more equipment and annunciator panels. That reduces the forward visibility significantly. Alas, there seems to be no free lunch, but with miniaturization of electronics and gauges, we should strive to have it all.
Any number of aircraft designers put the magnetic compass smack in the middle of the windshield where it blocks the pilot's forward scan, even though this instrument isn't used much these days. What about putting it in a less prominent spot?
Designing instrument panels is both an art and a science, which is probably why only a few are really good. As we start to move into flatpanel dot-matrix/liquid-crystal displays and other twenty-first-century equipment, we should consider a basic tenet of human factors. Simplify and provide only the information that is necessary for safe and precise flight. Bring up abnormal indications quickly, and ignore routine indications. Manage by exception. For example, if engine functions were incorporated into the flat-panel display, oil pressure and temperature wouldn't need to be shown once they entered the normal range, though they could be programmed to appear under certain flight conditions such as when in climb or descent.
Circuit breakers are not usually a critical item, but the really important ones that might need to be disabled in a hurry, such as electric pitch trim, autopilot, landing gear motor, etc., should be in a conspicuous spot and color coded to help.
The same goes for toggle switches. Put them where pilots are unlikely to get the wrong ones, group them logically, and color-code them, so less squinting at legends on the panel is needed. The switches should be large enough to operate reasonably accurately in turbulence and should be placed such that they don't leave a permanent impression on the frontseat occupants in the event of a sudden stop.
Here's a real high-tech idea that Piper uses and anyone could dupli- cate: Put the before-landing check list on the instrument panel. Keep the legal department away so that only operationally functional items are included. The downwind leg or approaching the final approach fix, when most landing checks are run, is a busy time when we don't want to be fumbling with another booklet, plastic card, or electronic check-list gizmo. It's a time to keep your eyes outside as much as possible. Most other checklist times afford us the luxury to use the aforementioned items without being so distracted with the aircraft and traffic.
Landing gear switches for retractable gear aircraft should be made as goofproof as possible. Inadvertent retractions do hundreds of thousands of dollars of damage every year. Beech is to be commended for the use of multiple squat switches on the main gear of its late- model aircraft. Squat switches are mounted on the main gear and prevent retraction when the aircraft weight is upon it.
Piper used to have one of the best automatic antiretraction and extension systems on the Arrow and Saratoga. It measured airspeed, and when the speed dropped below the trigger point, it would automatically extend the gear. The system assumed that if you were going that slowly, landing was imminent. Inadvertent retractions were prevented until the airspeed was high enough that the airplane.had to be airborne.
It performed admirably, and on short-field takeoffs where it was essential to retract the gear before the trigger speed was reached, there was a simple override to allow immediate retraction. However, this foolproof system occasionally was fooled. There were a few accidents where pilots departing from short fields forgot to use the override. The aircraft didn't clear the trees, and some innovative engineering was sacrificed on the courthouse steps. It's time to reconsider this type of system.
Cessna has some of the bestdesigned flap switches in the business, where approach flaps and landing flaps are easily selected by detent. The flaps stop automatically at the selected point. During rejected landings, simply select approach flaps and concentrate on flying the aircraft. Incidentally, the manual flaps on the Cherokee series, with their mechanical detents, are just as good. It can all be done by feel.
A full-flap warning system might be tied into the same throttle switch that is wired into the landing gear. If the engine is producing a lot of power, a light would remind us if the flaps are fully extended.
On large aircraft, trim tabs are usually indexed with numbers, as well as green bands, to indicate the proper setting for takeoff. This is done because even Arnold Schwarzenegger has to work at muscling a heavy aircraft that's mistrimmed. For our airplanes, marking the pitch trim wheel would be more a matter of convenience. Beech is the only manufacturer I'm familiar with that numbers ele- vator trim tabs on piston aircraft. It's very handy to be able to set "6" for takeoff and " 12" for landing with full flaps and know just about how much pull will be needed.
In the young days, before presbyopia set in, a single red or white light was all I needed to see what was going on in the cockpit at night. But having squinted at more than a few charts and looked for many switches since then, I have come to appreciate really good lighting. One of the reasons that the night accident rate may be so abysmal is simply that pilots can't see what they're doing.
Every cockpit should have flood and instrument lighting. Areas where charts will normally be placed, such as on the yoke or in the pilot's lap, should have pinpoint, dimmable white spotlights. Internal lights are nice on the gauges, and all legends should be illuminated. Electroluminescent panels, the kind that glow in the dark, are wonderful for reading the legends and switch positions. Nobody under the age of 45 should be allowed to design the night cockpit.
While we're on the subject of lighting, exterior lights could stand to be more conspicuous. Years ago, the FAA started a campaign called "Lights On" (or something to to that effect) to encourage pilots to use landing lights in the traffic pattern.
The forward-facing recognition lights that pulsate are a great idea, but many midair collisions involve one aircraft overtaking another from behind, above, or below. If we're serious about making see and better, this is an area that some additional emphasis, nice to see some rearward and sideways facing lights.
Aircraft seats should be supremely comfortable, and the slower the aircraft, the better they should be. A Cessna 172 should have better seating than a Lear because the occupants are going to spend much more time in them. Good lumbar support is a prerequisite.
Seats have much to do with safety because they must be adjustable to provide the pilot with the best outside view possible, reduce fatigue, and prevent injury by energy absorption in a crash. A good adjustment and locking system is essential and a bit tougher to engineer than for automobiles, because there are greater weight restrictions and the need to absorb potential crash energy from below.
A four-point harness restraint system is needed for each seat. All bizjets have them, at least for the crew. It has been shown many times that an effective upper-body restraint system is worth more than platinum in an accident.
Backup systems are pretty standard these days on new aircraft, but some additional attention should be directed toward the retrofit market and maybe some extra thought given to the weak-link theory.
Almost everyone flying much IFR these days has a backup vacuum sys- tem to drive the attitude and heading indicators. If you're not so equipped, I'd strongly recommend it. A request pending before the FAA would allow substitution of a non-tumbling electric attitude indicator as an optional replacement for the turn coordinator or turn-and-slip needle. It's a reasonable proposal and should be ap- proved. Sometimes we already have a solution that just needs some implementation.
As we put more electronic eggs into the communication and navigation basket, redundant electrical sources become essential. Dual alternators are an excellent idea if we can afford the weight. What about designing a lightweight power source?
The concept of an essential bus is a good one, and we aren't discussing urban transportation here. A bus is a power distribution system that brings the juice in from the alternator and battery, and all other circuits are tied into it. It happens occasionally that an electrical failure is not in the supply side-alternator or regulator-but that the bus or distribution system has failed. An essential or emergency bus system divides the distribution up, so at least one com and one nav system is functioning, along with basic lighting and landing gear. That's enough to get back on the ground safely.
The same concept applies to the audio panel. Redundancy would ensure that if a transmit relay blows, you won't be incommunicado even though both coms are working fine. A hand-held transceiver also can serve as a backup, but there should be an external antenna jack wired in so the hand-held's range can be significantly improved. The "Rubber Ducky" antennas that come with most hand-helds just don't have the punch.
Here is an area where we could spend days talking about what ought to be, but to keep this simple and focused, let's go with existing technology. Single-lever power controls for piston engines would simplify life in the cockpit. This would eliminate the mixture and propeller controls. jet pilots don't have to tinker constantly with powerplant adjustments-set the number you want on the gauge, and concentrate on more crucial things. Improper leaning, overboosting, and a multitude of other sins can be alleviated with this.
Electronic ignition, which goes hand in hand with the single-lever control, should also be incorporated. Easier starting, better temperature control, and greater fuel efficiency are some of the benefits of catching up to the twentieth century.
As mentioned earlier, we have far too many fuel-mismanagement accidents. The fuel system should be as simple as a brick. "On" or "Off are the preferred choices, with an appropriate lockout for "Off" and an annunciator to help prevent surprises, particularly when running on auxiliary tanks or crossfeed, which are unacceptable for takeoff or landing.
Barring that, for the retrofit crowd, a simple timer/fuel-flow transducer system might help. These exist but should be in wider use.
The military has done much to prevent after-crash fires by using selfsealing fuel lines with check valves to prevent fuel spillage. Perhaps some of this technology can be applied to light aircraft.
In the 1960s, before many pilots had instrument ratings, wing revelers were popular. Some of them operated fulltime, like Mooney's "positive control" system. The intent was to save the bacon if the pilot inadvertently got into the clouds.
I've heard that one of the Air Force fighters has an Aw Shucks" button. If the pilot puts the aircraft in an untenable attitude, the "Aw Shucks" mode of the flight control system rolls and pitches the aircraft back to upright and wings level. Granted, the govern- ment spends a lot more on its autopilots than we do, but because the technology has already been developed, maybe there's a way to apply this to our airplanes.
As I write this, the trip I'm hoping to make tomorrow is in doubt due to the possibility of airframe icing. One of the weak points in general aviation is that our equipment doesn't always meet the mission requirements. Little development has occurred on deicing and anti-icing systems for lightplanes for the past decade or so. Technical and cost barriers are there, to be sure, but the payoff could be significant, particularly if an icing system could be installed for less than $10,000.
We've all been told this stuff isn't easy or it would've been done by now. That may be true, but sometimes it's just the hardening of the thought processes that is defeating. Now, if Jimmy Doolittle, Clarence Kelly, and the Wrights were discussing this, we might get some action.
Recognizing that we've just scratched the surface, send your wish list to the AOPA Air Safety Foundation, 421 Aviation Way, Frederick, Maryland 21701. There may be an opportunity where good ideas could be explored further.
Aircraft Power and Fuel,
Aircraft Components and Gear,
Frazzled? What if your airplane could sense you're overloaded and take some piloting tasks off your hands?
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