The Rest of the Story

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I thought I had covered the whole subject of the controller/pilot interface pretty thoroughly. In the January 2008 issue ("The Controller Failed to Inform..."), I used two accidents to illustrate the perils of depending on the controller to keep out of weather and away from high terrain. In the July issue ("Saved by the Controller") I presented the other side of the story, describing two of the many cases where the controller did in fact save a pilot from almost certain harm. Then last month I shared advice from a book by John Stewart on how pilots can do their part in "Working With Controllers."

A seven-page letter I received from Craig Drake, a general aviation pilot who works as a controller at Denver Center, convinced me that there was a lot more on this subject pilots need to consider. Because Craig is both a pilot and a controller, he has a unique perspective on some of the topics I had covered. It turns out that the whole issue of why a controller may not warn a pilot about bad weather or high terrain ahead is much more complicated than I ever imagined. It just so happened that I was on my way to Denver to provide Error Prevention Training to Lockheed Martin Space Systems and United Launch Alliance employees the following week, and I arranged an appointment for a tour of Denver Center so I could see for myself what Craig was talking about.

Like many pilots, I assumed that controllers have a terrain display similar to what is available on even some of the most inexpensive GPS units. It seemed like it should be simple for a controller to see an airplane heading towards high terrain and issue a low altitude safety alert, and it was hard to understand how a controller would not issue an alert when appropriate, or could even vector an airplane towards higher terrain. As Craig says, "The FAA says it's our job, training manuals say that we will do it, and perhaps tragically, some pilots may depend on it in low visibility conditions."

Craig explained to me that it is not at all that simple. He showed me his display for the sector he often works west of Denver. The display looked to me like a puzzle maker had gone wild and tried to fit as many oddly shaped pieces of different sizes as possible into one area. Each piece, which is actually referred to as a polygon, has an associated altitude called the Minimum IFR Altitude (MIA) that provides 2,000 feet of terrain or obstruction clearance in mountainous terrain from the highest obstacle out to four nautical miles from its boundaries.

The terrain within each polygon may include mountain peaks and valleys that vary in elevation by many thousands of feet, yet the radar display doesn't show any mountains or valleys, "just large areas encompassed by high altitudes that the majority of airplanes we give VFR flight following to will never reach," and all airplanes departing from or approaching an airport in a polygon will of necessity be below the MIA. For this reason, the low altitude alerting system, which is set to alert the controller when an airplane is below the floor of the MIA for that polygon, is automatically inhibited for VFR airplanes and for anyone close to their departure point or destination. Otherwise the alarms would be going off all the time.

For example, the MIA in the vicinity of the Continental Divide is 16,000 feet, with higher areas around Mt. Evans and the Rocky Mountain National Park. Yet Craig says that every VFR day he watches numerous airplanes crossing that area at 11,000 feet or less, 5,000 feet or more lower than the MIA. The only way Craig could be sure they are going to make it would be to use a Sectional Chart located above his console to try to plot the moving airplane's location and then determine the terrain elevation at that specific location. Obviously a controller who is busy working numerous airplanes will not have the time to do that unless it is an emergency situation.

Thus the controller is in a tough position. Most of the mountain airports and VFR airplanes requesting advisories in that area are between 4,000 and 8,000 feet below the published MIA. If the controller issues a terrain advisory to every airplane arriving, departing or transiting the area below the MIA, pilots will get annoyed and will quickly disregard those advisories. On the other hand, if an airplane that did not receive an advisory crashes, then everyone wants to know why the controller did not warn the pilot.

Craig said that many controllers try to strike a balance by routinely advising VFR traffic of the MIA in that area. Some pilots seem to understand what is going on, but others get confused and reply that they can't fly that high or that they don't have oxygen. Occasionally pilots just cancel flight following. Even worse, if a pilot who is tracking down a valley in poor visibility receives a safety alert because he is below the MIA, he may turn towards the higher terrain on either side when he would have been safer proceeding straight ahead, and the controller would be blamed for turning the airplane into the terrain.

Craig said a similar situation exists regarding the weather information available to controllers. They now have Nexrad available on their display, which is much better than the old system of displaying lines to indicate moderate precipitation and H's for heavy precipitation. However, the Nexrad "seems to be far more sensitive ... and seems to cry wolf a lot. I have issued 'extreme' weather to pilots and had them reply, 'center, there's nothing out there!' " On the other hand, the center display may not show anything, and yet airplanes are requesting significant deviations for weather along that route. After issuing many "false alarms" or watching airplanes fly through what appears to be extreme weather with no problem, it is understandable that controllers may be hesitant to issue weather guidance to pilots.

Craig had some interesting comments about the incident I discussed in which the controller turned a Learjet that had just departed VFR towards higher terrain at night without any warning to the crew about the terrain. As I mentioned in my article on "Working With Controllers," controllers take into account the presumed experience and professionalism of the pilots they are dealing with. They obviously can't treat a student pilot the same way they treat an airline or corporate jet pilot, and professional pilots would be offended if controllers handled them like a student pilot.

Craig told me the controller would assume that a Learjet was flown by professionals who had carefully planned their departure as they are required to by the FARs, and that they "certainly would not be flying towards the mountains if they were not going to climb." The controller would also be aware of the incredible climb capability of a Learjet, but would not be aware that the crew was leveling off to stay VFR below the clouds unless the crew told him.

Thus controllers are between the proverbial rock and a hard place. On the one hand, pilots don't want controllers trying to fly the airplane for them, and numerous safety alerts to VFR airplanes that are flying through mountainous terrain would get old very quickly. On the other hand, it is very easy for a pilot on flight following or on an IFR flight plan to be lulled into complacency that the controller is watching and will tell him if he is approaching high terrain or bad weather. Pilots flying IFR en route receive more protection because the controller knows when they descend below the assigned altitude, but VFR airplanes flying in mountainous areas and IFR airplanes on departure or approach do not have the same protection, because by definition they will be flying near the ground and below any designated safety alert altitude.

As always, it is our responsibility as pilots to carefully plan all aspects of every flight. It can be reassuring to know that a controller is keeping an eye on us, but being in radar contact does not in any way reduce our responsibility as pilot in command to stay on top of all aspects of the flight and to be prepared for whatever lies ahead. It is especially critical to take the time to plan a departure or arrival at night in an area with high terrain in the vicinity. Anyone who departs VFR planning to pick up an IFR clearance in the air is on their own until they reach the MIA.

Above all, remember that controllers can't read minds. They can only help a pilot who calls them at the first sign of trouble and clearly communicates their situation without holding anything back because they are afraid of getting in trouble. Greg Dyer, the manager of Airspace and Procedures at Denver Center, said that for every 50 pilots who get into a difficult situation and are asked to call after they get on the ground, there is usually only one pilot who actually gets a violation. In most cases, as long as there was no loss of separation and the pilot seems to have a good attitude and understands how to avoid that situation in the future, there will be no further action or at most the pilot will be asked to talk to an accident prevention counselor.

As Craig says, "If you are in doubt and you aren't getting the help you need, declare an emergency and ask the controller to get a sectional and help you get to an airport or to lower terrain. If you fail to communicate the seriousness of your situation you may only hear, 'The MIA in your area is 16,000 feet,' which won't help much when there is a cloud deck above and the road you were following at 8,000 has disappeared. Please understand that if you are below my MIA, then only you can determine if you are at a safe altitude."