Last time we talked about a VFR training flight that tangled with mountainous terrain in the dark, and there was some discussion regarding synthetic vision or syn-vis. I had recommended the old-fashioned way of looking at the chart, VFR or IFR, to determine the Maximum Elevation Figure (MEF) or the Minimum Obstruction Clearance Altitude (MOCA) and Off Route Obstruction Clearance Altitude (OROCA).
A few of you wrote to suggest how helpful it was having the world electronically presented. We agree. A few old-timers will remember TWA 514, a Boeing 727 that slammed into a ridge just west of Washington, D.C.’s, Dulles Airport on a stormy VOR approach. The crew debated what “cleared for the approach” meant and what was a safe altitude for descent. That changed the whole system and lead to the formation of NASA’s Aviation Reporting System (ASRS). That landmark accident is required reading for anyone not familiar.
In the aftermath, all airliners were mandated to be equipped with ground proximity warning systems or GPWS. It sort of worked but didn’t look sufficiently forward. Airplanes continued to have terrain encounters and an improved system called enhanced GPWS was mandated. This has worked really well but not quite perfectly. (Airline readers may wish to weigh in on this.) With GPS, flat screen displays, and terrain mapping, GA moved into a new era about 15 years ago. If you’ve got the good stuff on board there really is no excuse to hit the ground or an obstacle. But it’s moderately to extremely expensive and updates are recommended.
A short hangar story: On a recent daytime VFR flight into the D.C. Special Flight Rules Area (SFRA) I was cleared into that sacrosanct airspace and told to remain clear of Class Bravo airspace. The floor of that airspace is 1,500 feet, and the small, but immovable ridges were coming up below me.
It was windy and bouncy down low. I asked ATC if they might grant another 500 feet as the last generation terrain map (not syn-vis) on my GPS unit was showing lots of yellow and a “terrain advisory.” That means less than 1,000 to go to touchdown. The box was insistent, as it should be. The terrain database was original to the unit—circa 2007. To be sure, while we’ve had an earthquake in the D.C. area (not political) the hills just haven’t moved all that much since then.
The tower topography, however, has changed and is changing drastically, and so tiptoeing through the tulips is not recommended even with a current database. A data point for your consideration: It’s too soon to know about any ground proximity systems aboard a VFR Piper Lance that collided with a wind turbine a few hundred feet agl at night in MVMC to IMC conditions, resulting in four fatalities. (South Dakota in April 2014.)
On my return flight out of the SFRA, it was well after dark but great VFR weather. Slide out at low altitude VFR and remain clear of Bravo, refuse that clearance and work out a VFR clearance into Bravo, or file IFR? What would you have done?
Syn-vis is excellent and my uneducated guess is that we will see fewer controlled flight into terrain (CFIT) accidents going forward, especially if the FAA relaxes the requirements for lower cost panel-mounted gear. It should be considered supplemental and installed with fewer restrictions than what currently exist. Pilots also need to understand that the good is not perfect so a terrain avoidance plan is still an excellent idea.
Belt and suspenders may not be stylish, but I guarantee your posterior will not be exposed. Would like to hear from you—both good and not-so-good experiences—regarding syn-vis and other electro-vision devices.
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