Safety Publications/Articles

Foundation Perspective

The GPS syndrome

Are instrument pilots being 'dumbed down'?

Totally enamored with your new IFR-certified GPS box? Ready to toss your VORs and ADF equipment out on the tarmac? Before answering, consider the following scenario:

The pilot was on the final leg of a cross-country flight. He had installed a new IFR-certified GPS in his airplane a year ago. He had become very comfortable with the new unit, and he often declared that it was one of the best things to ever happen to his flying. In fact, the new IFR-certified GPS unit was now his primary (or more accurately, his only) source of navigation. The moving map told him where he was, and many formerly arduous IFR tasks were now automated.

Weather at the airport was 800 feet and three miles' visibility, and ATC cleared him for the GPS approach to Runway 22. This wasn't the approach he had programmed into the GPS, and in the process of reprogramming he lost 300 feet of altitude, and his heading deviated 30 degrees. Fortunately, he recovered before ATC noticed.

Then the unbelievable happened -- the GPS display went blank, and the whole unit shut down, including the integrated com. He noticed that the GPS circuit breaker had popped. He reset it, but it immediately popped again. He tried unsuccessfully to reset it two or three more times. A sense of panic began to set in as he scrambled to find the ATC frequency and set it in his second nav-com radio.

The controller gave him a heading to intercept the localizer for the ILS 31 approach. By this time the pilot had to admit to himself that without the moving map, he didn't really know exactly where he was, but he followed the ATC instructions.

He was two miles from the localizer when the controller cleared him for the approach. While getting out the approach chart he flew through the localizer, made a 45-degree banked turn back to the localizer, and flew through it again. He was finally able to track the localizer, but by this time he was far above the glideslope with the outer marker behind him. Rather than diving at the ground to intercept the glideslope, the pilot wisely informed ATC that he was going to do a missed approach and try again.

The next approach was better, but he never was able to properly stabilize the aircraft. He executed some S-turns on the localizer and porpoised down the glideslope. Fortunately, the weather was well above minimums, and the pilot made a safe landing. (Note: This pilot was current according to FAR 61.57, but the regulation only calls for six approaches in six months, all of which could have been nonprecision GPS approaches.)

This scenario probably happens rather frequently, based on the performance of some pilots with GPS-equipped airplanes to whom I recently have given instrument proficiency checks (IPCs). It appears that instrument pilots who were at one time highly skilled are now joined at the hip to their GPS boxes -- to the exclusion of all other navigation equipment. While conducting an IPC in a GPS-equipped airplane, I normally turn off the GPS sometime during the flight and have the pilot fly without it. Frequently the pilot becomes confused and disoriented. The pilot who is used to flying along a magenta line on the moving-map display may have difficulty centering the CDI on the VOR radial or intercepting a radial. When deprived of a moving map, GPS-centric pilots are deviating more and more often from localizer courses.

There is no question that GPS is the navigation and approach system of the future. It enhances safety and improves situational awareness, and, once mastered, it makes IFR flying much easier. But those who totally embrace the new technology and abandon their basic IFR skills are taking an unwarranted risk. Two GPS units are better than one, just as it is with two nav-coms. But even then, it's still wise to maintain conventional IFR skills. What if a pilot flies an airplane with no GPS or another brand of unit with dissimilar controls? What if there is a complete electrical failure and one has to rely on the VOR feature of a handheld radio? That's when you really need your IFR skills. As instructors, we can bring a sense of perspective to pilots and students whom we train and teach them not to, dare I say, put all their eggs in one basket.

While the deterioration of skill when tracking VOR radials, localizers, and glideslopes is notable, another frequent oversight is failure to positively identify navaids. When going from waypoint to waypoint on a GPS flight plan, pilots don't have to identify stations. But when using conventional navigation, station identification is essential.

I recently conducted an IPC in a GPS-equipped airplane, and I told the pilot to ask for the ILS approach to Runway 29 at a nontowered airport. About 10 miles out, I had to remind the pilot to identify the localizer. There seemed to be a carrier, but no code identifier. The pilot noted there was no notam that the localizer was down and there were no flags showing a failure of the localizer. A call to ATC and the FBO indicated no known problem with the localizer. The pilot said, "There must be a problem with the code generator in the localizer." Since it was severe VFR, I let this comment pass and allowed him to proceed, and ATC cleared us for the approach. The GPS showed us almost to the localizer, so I shut it down, simulating a failure. The CDI was close to center, and the pilot turned to what he thought was the localizer. He intercepted the glide-slope and proceeded down. There were still no flags, but no identifier either.

As we proceeded toward the runway, I noted that the wind from the right was moving us left of the extended centerline. Before long we were lined up on a road that ran behind the terminal, about one-half mile left of the runway centerline. The CDI was still centered. (Why there were no flags is still a mystery.) Had we continued, we would have touched down in the parking lot of the local Burger King. I had the pilot remove his hood and do a missed approach. Later, the FBO attendant told us that a lawn mower had clipped the localizer antenna about 15 minutes before our arrival. I hammered home this mantra to the pilot: "No code, no approach." Had this pilot been in hard IFR conditions, I'm not certain there would have been a successful outcome.

Another pilot with whom I flew would use the GPS to track airways and wouldn't use a VOR as backup. He would simply follow the magenta line that designated the airway and occasionally check the digital readout of the aircraft's track and VOR radial. When I shut down the GPS, he mistakenly entered the frequency 112.3 in the VOR instead of the proper frequency of 112.6. As it happened, the VOR station on 112.3 was off to the left by only 20 degrees and 30 miles farther than his intended VOR. Noticing his mistake, I reminded him to identify the station. A few years of GPS flying had desensitized him to the need. He heard the ID code and informed me he had the station but didn't bother to check if it was the correct identifier.

After about 10 minutes, I turned the GPS back on. The pilot was surprised that the GPS showed him left of the airway. The pilot immediately concluded that his VOR was "out of tolerance." I then pointed out the error of the wrong frequency. Yes, the GPS would have kept him on the airway, but in this case the GPS failed, and the pilot had to count on his basic VHF navigation. The errant track he pursued could have taken him into higher terrain, resulting in a controlled flight into terrain accident.

Identifying a navaid is more than just hearing the sound of the code. Pilots must know what the code is saying. Most pilots don't know Morse code, so they must rely on the printed dashes and dots on their charts to make a proper identification. Teaching students to remember to always identify stations is a hard lesson to get across and one of the first procedures they forget after they get their rating.

When conducting IPCs, it is essential to determine that a pilot's conventional IFR skills are up to snuff as well as his or her GPS competence. Instructors need to drive home the notion that we cannot just sit back and let the GPS box do all of the thinking for us. GPS is just another tool in the toolbox, not the pilot in command. Instructors need to stress that pilots must continue to practice conventional IFR procedures without the aid of a GPS. While using an IFR-certified GPS as a primary navigational source, it is essential to have the conventional VHF equipment running in the background as a cross-check and ready to take over if needed. GPS is a marvelous invention, but we shouldn't go flying IFR without a safety net. Keep those basic IFR skills sharp.

Richard Hiner retired from the AOPA Air Safety Foundation as vice president of training. He can be contacted at [email protected].

By Richard Hiner

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