Avionics reflections from the rear view mirror
Brian Wilson walks us through some hair-raising experiences with aircraft cockpits over the decades to help illustrate how far Business Aviation avionics have come over the 37 years of his aviation career.
It was another hot and humid Saturday afternoon in South Florida, and I could feel the sweat running down my back as I carried my avionics test equipment aboard the B727-200. This aging jet had been used entirely as a freighter carrying anything from fresh fish caught in the Caribbean to young stallions destined for the lucrative horse racing tracks in Florida.
As I sat down on the torn fabric that encased the worn-out cushions of the pilot’s seat, the rancid combination of heat, humidity and fodder from the last haul seemed overwhelming. As my focus honed in on the avionics, it struck me that cockpits from that era more resembled the ones in the Smithsonian museum than today’s state-of-the-art glass and touchscreen panels.
With that said, there was one reliable system in that dated cockpit that today’s young pilots have probably only read about in their training manuals: Within that panel were two fully-functional Automatic Directional Finders (ADFs), which in its rudimentary form is no more than an AM radio with a bearing pointer. Once tuned to the proper channel my favorite college football team was soon broadcasting play-by-play action across the cockpit speakers – fancy that, my young aviators!
Fast-forward a decade and I was sitting in the jump seat of a Gulfstream GI due to take-off from Madrid on a night flight to Brussels. The crew had not been satisfied with the performance and accuracy of the VLF/Omega navigation system recently installed and insisted on me joining the flight to share their experience.
The two turboprop engines shook the fuselage as the aircraft left the runway and ascended into the evening sky. Due to this being an all-night round-trip the crew was well prepared with espresso coffee, unfiltered cigarettes and jovial conversation spoken exclusively in Spanish. It was not long after we leveled-off that it was apparent the VLF/Omega systems were not receiving a viable signal and the crew reverted back to VOR/DME, a sophisticated form of dead reckoning.
Having just met my crew over a short briefing prior to the flight, and this being a start-up company with many new pilots, I was now searching for the emergency evacuation procedures in case the frigid North Sea or the English Channel became our ‘unscheduled’ destination.
Only after the young co-pilot turned to me and said in broken English “Eiffel Tower” did I feel comfortable we were on the right track. You see, we didn’t have a Multi-Function Display with a moving map and our flight plan, our position and weather on the screen. I had brought along a map of Europe for which I drew a line from Madrid to Brussels, and Paris was one of the intersecting cities!
Another occasion found me kneeling at the end of the pedestal of a Lear 55 as we were testing the radar stabilization operation that had been squawked numerous times by the crew. The flight was scheduled after lunch to better our chances of ‘painting some weather’, and the typical afternoon Cumulonimbus clouds didn’t disappoint us that day. One good thing about flying in Florida besides the flat terrain is having 1.5 million open acres of the Florida Everglades to one side and the Atlantic Ocean on the other side. On this occasion we requested a space over the everglades so we could paint ground clutter and adjust the stabilization.
The crew and I were focused on making calibrated turns, climbs and descents while adjusting the calibration potentiometers encased in the radar indicator. Having completed our mission we turned our attention to outside the cockpit for the flight back, only to see the clouds and pending rain storms scattered across the horizon…
The return flight had us going around, under and through thick formations of clouds and precipitation causing slight turbulence and blind spots from all sides of the aircraft. It seemed like ATC was vectoring us to a new heading every few minutes and warning us of traffic doing the same to escape the prevailing and shifting weather.
Since TCAS was just being introduced at that time, and coupled with high equipment and installation costs, we didn’t have the system onboard. I quickly realized that we did have our own primitive avoidance system; it was ATC warning us of the position of the local traffic and the three of us peering out the cockpit windows to locate and avoid potential danger!
The Evolution of Cockpits
The complexity of the cockpits in that era went hand-in-hand with the stick-and-rudder skills of the crew. There was a direct correlation between the standard set of six instruments in the cockpit of the aircraft in which these pilots did their initial training and the ones they were flying.
The crew had to be very cognizant of everything inside and outside the cockpit often relying on their own initiative and perception, commonly referred to as “flying by the seat of their pants”.
Any seasoned avionics technician in that day could fix most cockpit squawks with a #2 Phillips screwdriver, a Simpson multi-meter and a set of wiring diagrams.
The first generation of pilot instruments was electro-mechanical (i.e. they had internal servo motor-generators that mechanically steered the instrumentation for pitch, roll and azimuth). Remote Instrument Amplifiers were needed to interface the existing systems like the flight director computer, vertical and directional gyro with the ADI and HSI.
These instruments soon were being replaced with Electronic Flight Instrument Systems (EFIS). These color Cathode Ray Tubes (CRTs) were heavy and had a high current draw, but brought reliability and redundancy to the cockpit. The early generation used three small 4-inch displays driven by remote Display Processing Units (DPUs).
The third display was actually a second EHSI mounted in the center panel that had a weather radar display feature when paired with a compatible radar system. The three-tube system quickly evolved into a five-tube system with a fully functional MFD replacing the legacy radar indicator.
Advancements in technology resulted in the CRT generation being replaced with Liquid Crystal Displays (LCD) that ran cooler, were smaller, and reduced or eliminated the amount of the remote units required to run the displays. Since the earlier models replaced the ADI and HSI they had a vertical profile which was commonly called the ‘portrait’ display. Newer models, which had a horizontal (‘landscape’) profile, quickly caught on as almost all the previous instrumentation was swallowed up in this new architecture.
Today’s cockpit resembles more of a spaceship from a Hollywood movie, with high-resolution flat-screen monitors positioned end-to-end across the panel.
A pilot’s interaction with the aircraft is transcending from two hands on the yoke to one on the side-stick controller and the other on the point-and-click trackball controller. Crew members can rely on increased safety and advanced situational awareness due to technologies not available to the business aircraft just 25 years ago, including TCAS II; EGPWS; RVSM; Enhanced Vision System (EVS); Head-Up Display (HUD); GPS/WAAS/LPV; Synthetic Vision; and Runway Awareness and Advisory System (RAAS).
Many pilots who have flown for 25-plus years will recall their own harrowing experiences with cockpit panels of yore, and wholeheartedly agree as to how today’s systems have reduced workload and improved safety, particularly as the number of aircraft flying increases each year.
NextGen (US) and SESAR (Europe) will address this particular concern with new technology for the cockpit and the Air Traffic System, allowing aircraft to fly closer together both laterally and longitudinally in the same way RVSM tightened the vertical limits.
In the 37 years I’ve been in aviation (military, commercial and business) it is the cockpit that has seen the most profound changes. I can only imagine what today’s engineers are drafting for the next generation, but I will always remember when a simple AM radio was all I needed!