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GPS For IFR

Evaluating Student Understanding

We received a thought-provoking telephone call from a designated pilot examiner the other day. He voiced a familiar concern: "How can I evaluate an applicant for the instrument rating who brings an airplane equipped with an IFR certified GPS?" That's a very good question, and it's one that pertains to flight instructors as well as pilot examiners.

Many flight instructors are proficient operators of at least one approach-certified GPS, and their services are increasingly in demand as pilots equip with GPS. But many more instructors have little or no experience with satellite navigation. Trust me on this; GPS is not like VOR. A substantial commitment to study and practice is required before a pilot can fly IFR GPS in safety and confidence. You can't figure out how to operate it by looking at the panel. And proficiency with one brand of GPS by no means guarantees proficiency with any other. The receivers all do essentially the same thing, but how they are operated varies greatly from manufacturer to manufacturer and, to a lesser degree, from model to model within a product line. As the products evolve and pilots gain experience, GPS should become more "intuitive." But, for the moment at least, flight instructors should specialize in teaching one manufacturer's product.

When you're proficient in teaching and flying with one unit you can expect to do a creditable job of evaluating student performance on the others. Here's what I told the examiner to help him construct his evaluation action plan. Instrument pilots should demonstrate proficiency in the following GPS operations:

¿ Understanding the basics of GPS navigation requires some new concepts, terminology, and procedures such as:

  • Great circle track navigation;
  • Receiver autonomous integrity monitoring (RAIM);
  • Turn anticipation;
  • Fly over and fly by waypoints; and
  • Differences in charting between NOS and Jeppesen. Instructors must be certain their students understand the basics of how GPS works, how to know if the navigation information is reliable, and how to comply with approach and missed approach procedures.
  • Programming a waypoint and flying direct-to is the core GPS pilot operation. It's surprising how many IFR GPS owners can't or don't do anything but fly direct.
  • Holding on a waypoint: GPS is designed to navigate direct from one waypoint to the next in a sequence of waypoints. Once a waypoint is reached, the receiver sequences to the next waypoint, so in effect you're always going someplace. In order to hold, waypoint sequencing must be interrupted, and the pilot will have to maneuver with respect to a specific course. Avoid using published holding points when evaluating pilot performance. Instructors should simulate ATC instructions to hold on a specific course at a designated fix.
  • Programming an instrument approach procedure: GPS approach procedures consist of a sequence of waypoints stored in the memory of the receiver. Pilots must know how to select the approach they want and arm it. When the aircraft is within range the approach mode will become active, and the procedure can be flown.
  • Flying a GPS approach procedure from an initial approach fix: This will involve selecting the appropriate initial approach fix, navigating to it and, through a series of waypoints, navigating to the missed approach point.
  • Abandoning the procedure prior to reaching the missed approach point and flying vectors to the final approach segment of the procedure: This is where things can get interesting. Some GPS receivers require a considerable amount of button-pushing and knob-twisting to get set up to repeat the approach. You'll want to know your student can maintain situational awareness, communicate, navigate, and aviate while close to the ground.
  • Flying a missed approach procedure that requires navigation other than direct from the missed approach point to the missed approach holding fix: GPS receivers automatically suspend waypoint sequencing at the missed approach point, so pilots must take some action to sequence the receiver to the missed approach holding point. Once this is done the receiver will navigate direct to the MAP, but that isn't always the way the missed approach procedure is designed. You must be assured your students can "climb on runway heading to 4,700 feet before turning left direct to the MAP and hold."

There are many more GPS functions available on today's receivers. Flight plans can be programmed and stored, nearest airports and navaids can be seen, moving maps can be displayed and scaled, and a wealth of airport and frequency information can be accessed. That's all nice to know information that's effortlessly acquired by black-belt GPS users, but the core operations are the ones that are essential. Proficiency in these will ensure safe GPS navigation.

By John Steuernagle

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