December 8, 2016
Controlled flight into terrain
Controlled flight into terrain
In January 2008, the National Transportation Safety Board (NTSB) issued Safety Alert 13, warning pilots of a rash of accidents involving controlled flight into terrain (CFIT).
The unique aspect to these accidents is that many were under ATC control at the time of the accident and all were in night-time visual conditions.
Accident pilots were either operating under instrument flight rules or visual flight rules, which seems to indicate that neither operation is inherently safer than the other.
The NTSB gives several recent CFIT examples, including a Learjet, two Beech–Raytheon King Airs, a Cessna 182, a Piper Saratoga and Cherokee. All of these accident occurred in what I call “terrain challenged” areas; that is, areas that are anything but flat!
The major “take-home” lesson from all of these accidents is that they were probably avoidable.
“Controlled flight into terrain” is a phrase that invokes images of a pilot asleep at the controls. Unfortunately, the truth of the matter is that these pilots were likely far from asleep, but rather were simply unaware of their position.
In many cases, pilots rely on air traffic controllers (ATC) to keep them clear of obstacles. After all, controllers have minimum vectoring altitudes and low-altitude alerting systems to keep pilots out of trouble, right?
Well that may work some of the time, but I have personal experience that proves it doesn’t work all the time. All it takes is a unique set of circumstances to come together at the right time and even if a controller finally spots a altitude problem, it’s already too late.
Preventing CFIT is not simply a matter of proper navigation radio setup, safety pilot monitoring of the flight, nor familiarity with the area alone, but a combination of all of these factors.
Since reliance on the controller alone is not advisable, pilots must become intimately familiar with the expected flight routing and underlying terrain. However, the real key is the maintenance of situational awareness at all times during the flight. This means keeping track of the current position by all means possible.
The instrument pilot would seem to have an easier time of keeping track of their position, since much of their flying is done via reference to ground or satellite based navaids. But when radar vectors are flown, it is much easier to lose track of the aircraft’s position.
The level of situational awareness necessary during radar vectors can be debated, but I like to be at a level so that I could proceed on my own should radar contact be lost. It takes a lot of effort to maintain that level of awareness, but it’s preferable to becoming a permanent fixture on a mountainside.
In the safety alert, the NTSB goes on to make several additional recommendations, most aimed at the VFR pilot. They recommend that a careful study of sectionals or other topographic references is made prior to visual operations at night.
This is good advice, but it is only as good as the pilot’s ability to maintain the pre-planned course over the ground. Remember that at night in poorly lit areas terrain may be invisible and a horizon reference may not exist. As a result, it is recommended that VFR pilots flying in these conditions follow IFR practices for terrain clearance.
Climbing on a known course to safe altitude and then cruising at 1,000 above the ground or highest obstacle, or 2,000 feet in mountainous terrain, is a good idea.
A GPS-based terrain awareness unit is also good for keeping a safe distance above the ground. Bear in mind however, that GPS units are only as good as the installed database, so be sure to have an updated database at all times.
A few words about VFR flight and air traffic control are in order. Many pilots are under the impression that if they are in contact with ATC (flight-following for example) that their terrain protection has improved somehow. In many cases, this just isn’t so!
Control in visual conditions usually comes with a phrase like “maintain VFR,” and that means the onus of cloud and ground separation is squarely on the pilot’s shoulders.
Of course that doesn’t mean that the controllers will ignore a hazard if they see one, but you can’t count on them seeing it all the time since they have no requirement for positive altitude control of most VFR flights.
Also, the limited terrain warning features that are available from radar facilities are generally not configured to watch VFR traffic. However, controllers can activate this feature at the pilot’s request. Be aware that it is designed to watch for IFR altitude excursions, especially en route, and aircraft operating VFR below those altitudes may be given numerous false alarms.
The bad thing about false alarms is that the more you get, the more likely you are to ignore them in the future. That defeats the purpose of getting them in the first place!
In the end, situational awareness of terrain is really a function of the time the pilot has to spend attending to it. If it takes every bit of skill the pilot has just to fly the aircraft, then navigation and terrain awareness will likely suffer. This is an especially important consideration for novice pilots.
However, experienced pilots can be overwhelmed by complex aircraft as well, so finding a way to mitigate the potential loss of awareness is critical. Autopilots can come in handy in these situations, but they should not be over-used since complacency will set in over time.
The idea here is that the autopilot can take over flying while the pilot maintains supervision of the controls and monitors the navigation equipment to assure terrain clearance.
An extra pilot is also a good idea, but make sure he or she is in the control loop at all times. If the second-seater has little or no idea what you are doing, or plan to do, their assistance in maintaining vigilance for flight hazards will be diminished.
Controlled flight into terrain should be an avoidable accident. However, the pilot must be aware of their surroundings at all times. The pilot must be able to catch when ATC gives a bad vector and know what the correct vector should be in that case.
Anything less is flying blind and synonymous with a game of Russian roulette. Fly smart, fly aware, and let’s put a stop to these types of accidents!
This month’s Pilot Primer is written by Donald Anders Talleur, an Assistant Chief Flight Instructor at the University of Illinois, Institute of Aviation. He holds a joint appointment with the Professional Pilot Division and Human Factors Division. He has been flying since 1984 and in addition to flight instructing since 1990, has worked on numerous research contracts for the FAA, Air Force, Navy, NASA, and Army. He has authored or co-authored over 180 aviation related papers and articles and has an M.S. degree in Engineering Psychology, specializing in Aviation Human Factors.