The improvement in aviation safety is astonishing. No major US airline has suffered a fatal crash since 2001. Before this incredible 20-year period, the longest stint without a major airline fatal crash was barely more than two years.
Even regional airlines that previously did not come close to the safety record of the majors are now posting a near perfect record. In the past 20 years there have been only two regional airline fatal crashes, and the most recent was at Buffalo, in 2009. That’s more than 12 years ago.
We don’t have equally precise data on general aviation safety because we don’t know the exposure—the number of flights—as we do with the airlines, but all indicators show steady improvement in the GA record, too.
Though many factors contribute to the enormous advance in aviation safety—including some great flying and a solid dose of luck in the case of Sully and Skiles in the Hudson River—the single greatest factor is development of GPS.
Think about it. Before GPS we never knew our exact position and track. Of course, the ILS aligned us with the runway centerline with near perfection, but that was only for a tiny portion of the flight. And our location along the localizer track was fixed by marker beacons. Two, or at most three markers, told us for an instant our position with decent precision. Even with an ILS DME available, we only see our progress in tenths of a mile, which is little better than Kentucky windage compared to GPS.
Many of we oldsters spent much of our careers trying to fix our position with a clock. We had to estimated groundspeed and then compute that into an along track position by timing from the last fix crossing. And that fix may have been something no more precise than the intersection of two VOR radials. That seems crazy today.
The real safety improvements are the technology that flowed from knowing exact position fixed by WAAS GPS.
For example, the first ground proximity warning system (GPWS) relied primarily on a radio altimeter that looked straight down to measure height above terrain. Much better than nothing, but when flying toward rapidly rising terrain the GPWS pull-up warning would come to late. It happened to an airline crew at Cali, Colombia.
With GPS position, track, height, and velocity data constantly available, today’s terrain warning systems look ahead. The system stores a terrain map, compares that map to your GPS fixed position, track, and altitude and computes terrain clearance ahead. These systems show us areas where terrain clearance is marginal, and then if we persist in flying too low, they yell at us to climb.
GPS has also made possible synthetic vision. Now we can see not only the runway ahead, but any terrain features or obstructions nearby. Syn viz is so good, and so realistic, it’s really easy to fly an “instrument” approach using only the syn viz display. Many of us have done it in Level D simulators. I was fortunate to fly such an approach for real—with a safety pilot in the right seat, of course—with the Gulfstream test pilots when they were developing the first syn viz to be certified.
The penultimate safety advantage made possible by GPS positioning is Garmin’s Autonomi emergency automatic landing system. Autonomi—now certified in several airplanes—can, with the push of a button, autonomously select the nearest suitable runway, fly the airplane to that runway, and safely land on it.
Automatic landing has been used in airline airplanes for decades, but those Category III systems only operate on specially approved runways. Autonomi can land at any runway that has a precision approach such as an LPV or ILS. Incredible.
GPS also makes possible traffic warning derived from ADS-B position reporting. The entire ADS-B system depends on GPS position fixing in each aircraft. Because ADS-B automatically reports each aircraft’s position it’s possible to compare those positions and altitudes and calculate a collision threat and issue a timely warning.
Another very important GPS-enabled safety feature is weather in the cockpit. The images of Nexrad radar come down from the satellite to our airborne receivers, but without the precise GPS position fix we couldn’t see our location relative to the radar returns. I know, there are latency issues between when the radar tracked the weather and when we see it, but still, Nexrad radar in the cockpit is a huge safety advantage we oldsters could never have imagined just a few years ago.
GPS has also contributed to safety in some smaller, but significant ways. For example, fuel planning. We always had the clock to keep track of fuel burned per hour, but with GPS we know with precision fuel burned per mile. And exactly how many miles to the destination. And precisely where any suitable diversion airport may be. There was little excuse for running out of fuel before, but with GPS, there is absolutely none left.
I still see student pilots lugging around sectional charts and E6B computers and plotters. Maybe that’s OK, kind of like new sailors learning to tie a bowline. And maybe it will teach new pilots what we oldsters already know—GPS is the best thing to happen to aviation safety ever.