Are Needle, Ball, and Airspeed Obsolete?

With the advent of the Glass Age, I’ve been seeing more and more pilots question the need for traditional needle/ball/airspeed instrument skills. Why bother to learn the technology of yesterday, they ask?

On the surface, this question makes sense. After all, who even manufactures aircraft with non-glass panels anymore? Heck, even the venerable Legend Cub is being built with a Dynon D10A these days. At my home field, we have a Waco UPF-7 (a 1930′s era open-cockpit biplane) with a Garmin glass panel. It looks more like you’re sitting on the bridge of the starship Enterprise than in a barnstormer ready to dust crops.

There’s no doubt that glass panels have fewer insidious failure modes than analog instruments. Instead of an attitude indicator that slowly rolls over (possibly taking the pilot with it), you get a giant red “X” leaving no doubt about the quality of the AHRS data.

And, lest we forget, many of the pilots who balk at an six-pack instrument panel probably don’t see one that often. They fly newer airframes, experimentals, turbines, and read industry publications that rarely even show a non-glass instrument panel. Out of sight, out of mind. So the question is a good one, but my answer may surprise you.

In my opinion, the traditional analog instruments are not obsolete, if only by virtue of the fact that out of the 200,000+ GA aircraft in existence, probably 90% of them have the older style panel. These airplanes are mostly certificated in the Normal category, and it would be neither cost effective or legally possible to put newer style instrument panels into those aircraft at the present time.

Of course, if you have an RV-X and only plan on flying that airplane and it’s got glass and you can fly it proficiently (including partial-panel, whatever that may look like in your ship), then there is no need to be able to fly with a turn coordinator, altimeter, and airspeed indicator.

On the other hand, when I train students to fly IFR in glass airplanes like the SR22 and Columbia, I ensure they can fly a traditional six pack as well via simulator training. There are several reasons for this:

  • I want them to be a complete instrument pilot able to fly more than just an Avidyne or G1000
  • Second, I want them to understand the way analog instruments work since there are analog instruments even in those glass aircraft, and they have different failure modes and different scans than an AHRS-based system
  • Third, it’s harder to go “back” to analog instruments than it is to go “forward” to glass panels if you’re already a rated and experienced pilot, so I want the heavy lifting to be done while we’re already doing the heavy lifting: during primary instrument training.

I disagree with those who feel instructors are anti-GPS, anti-glass, attached to older technology, or provide unrealistic failure modes for no good reason. I know none who have that attitude. On the other hand, we often turn those devices off or direct a student’s focus elsewhere because it’s necessary for training. If we don’t push your workload to the breaking point, fail instruments and radios, etc. then we’re not doing our job.

Anyone can fly IFR when everything’s working. I’ve seen pilots who aren’t even instrument trained do it. But when you’re on one engine or partial panel in the clouds, a passenger is airsick, you need a bathroom break, the fuel is getting low, it’s night, and you’re tired, that’s not the time to find out how well you perform when stress is high. That’s why we push you hard. If you ever have a bad day and come out the other side in one piece, you’ll understand that.

RNAV Approach Quiz

From the “you learn something every day” file comes a fascinating Air Safety Foundation quiz on RNAV approaches.

For the non-pilots and/or non-instrument rated among us, RNAV is short for “random area navigation” and for the most part refers to satellite navigation — in other words, GPS. It’s not called GPS because there are other area navigation methods such as loran, omega, inertial navigation, and so on.

But they all do the same basic thing, which is to allow a pilot to fly from any random point in the world to any other point. Prior to RNAV, radio navigation consisted of flying from one ground-based station to another. A highway in the sky, if you will, but one firmly tied to the ground. These ground-based stations are housed in little buildings scattered around the country which transmit signals the aircraft’s navigation receiver can follow. The problem is, these buildings are not movable. They’re expensive to build, maintain, and monitor.

With RNAV, pilots can create virtual waypoints anywhere. RNAV systems therefore have more capability than the older ground-based navaids. If you’ve ever used a GPS, then you’re part of the RNAV revolution.

Of course, there has to be a down-side, right? Nothing is free in aviation, and so it is with RNAV. RNAV systems tend to be computerized and therefore more complex. They also tend to fly in the face of thing we’ve learned about IFR navigation. Curving approach paths, precision approaches without an ILS, etc.

For example, every instrument-rated pilot knows that in order to proceed below the published minimums for an Instrument Approach Procedure, three criteria must be met. In general terms, they are:

  1. The flight visibility must meet the published minimums for that procedure
  2. The aircraft must be in a position from which the pilot can make a normal landing using normal rates of descent
  3. The runway environment (pavement, lights, paint, etc) must be in sight

Aside from an esoteric 100′ rule dealing with a specific part of the approach lighting system, there are no exceptions. Or at least, that’s what I thought until the RNAV quiz taught me about “fly visual” segments.

“Fly visual” segments are typically seen on approaches to airports in mountainous areas. Treat them as red flags: If you see one, take some extra time and give the procedure a closer look.

There are a couple of reasons for this. First, as discussed in the main portion of the course, the visibility required for the approach is sometimes less than the length of the “fly visual” segment-meaning that the pilot can legally continue beyond the DA/MAP without the runway environment in sight, provided he/she has the required flight visibility. Obviously, this leaves a certain amount of room for interpretation. If you find yourself in such a situation, and there’s any doubt about whether to proceed (particularly if you’re not familiar with the local terrain and landmarks), it’s best to opt for the missed approach.

It’s also worth thinking about why the “fly visual” segment exists in the first place. Why did the designers of the approach essentially choose to “slide” the entire approach away from the airport by the distance of the visual segment? In many cases, the underlying reason is that terrain in the missed approach area would necessitate unreasonably high minimums if the MAP were in its normal position. By displacing the MAP a few miles, the designers can build a missed approach segment that doesn’t have terrain problems (a situation well illustrated by the NDB/DME or GPS-A approach at Hailey, Idaho).

Of course, the terrain is still out there, and the danger for pilots flying such procedures is that the unanticipated need to initiate a missed approach beyond the MAP can lead to obstruction conflicts (or, to put it more bluntly: a collision with a mountain).

The bottom line? For procedures like the one at Hailey, never continue the approach past the MAP unless there’s absolutely no doubt about the outcome.

Sounds like fun. Not! Imagine having 1/2 mile visibility and coming to the end of your RNAV highway in the sky, yet being permitted to continue flying visually without the having the airport in sight. TLAR (“that looks about right”) navigation at its best.

The scary thing about these approaches is that they occur in mountainous areas. By definition, these areas having high density altitudes in the summer and are prone to icing in the winter. A mountainous approach is one time I would want to start my missed approach segment earlier rather than later in order to assure adequate terrain clearance during the climb.

The RNAV Approach Quiz is free, and it was far more informative than I had anticipated. Normally I breeze through these things with nary a thought, but I really had to stop and think about some of the questions. And I must admit there were some things in there I didn’t know.




Switch to our mobile site