Instrument flying myths: What you don’t learn in training!

By Donald Talleur and Richard Talleur

Most people take pride in the accomplishment of becoming a licensed instrument pilot. Likewise, most of those people feel ready to venture out into the "goo" on their own quite soon after becoming instrument qualified. Unfortunately, there are a lot of myths and pitfalls of instrument flying that are frequently overlooked or forgotten during training. While these pitfalls are not all that terrible in some cases, they can surely make your life miserable unless you’re aware of them.

The first myth of instrument flying is indeed a pitfall of which all instrument pilots should be aware. The ceremonial checking of the VOR indicators before flight into instrument conditions is an old tradition and practiced by all pilots we’ve come into contact with. However, there are many ways to check your VORs and many pilots pick the worst method of checking them. We’re referring to the "dual" method of checking VORs, or the practice of aligning two VORs to the same frequency and bearing and noting the error between the two. If at least one of the VORs is working perfectly, you have a decent test of the other’s accuracy. However, consider the problem of having two VOR indicators that are both inaccurate. If they both happened to be in error in the same direction (same number of degrees of error in the same direction) they’ll appear to be in agreement with each other. This may lull the pilot into thinking they have two good VOR indicators, when in fact they have two bad indicators. For this reason, unless you’re really sure about what bearing you should see when you do a "dual" VOR check, we recommend that you stick with a ground receiver checkpoint or VOT to test the VORs.

The second myth of instrument flying is that "what you file your instrument flight plan for is what you’ll get." In reality, this is true only if you know what you’re going to get (from Air Traffic Control) and file it that way ahead of time. Generally, if you simply pick a route that is most direct to your destination you probably get cleared for something that resembles what you asked for. However, depending on the requested altitude, the assigned route might be slightly modified so you do not conflict with traffic that would normally use your original requested route at some other altitude. Be prepared for these small modifications even if you are "cleared as filed." The controller is allowed to give you that clearance and still make minor modifications to the actual routing once airborne. The corollary to this myth is that "what you are cleared to is what you have to fly." While we would never suggest that you deviate from a clearance without first being cleared to do so, if you would like a routing other than what you are cleared for, simply request it. Generally, the controller will work with your request, but be prepared for possible delays in route, especially if your requested route conflicts with other standard routes used by Air Traffic Control.

During basic instrument training, most pilots are taught about minimum altitudes for obstacle clearance and minimum altitudes for navigation reception. However, one area that is frequently glossed over is minimum communications reception altitude. If you’ve ever flown in mountainous terrain or at the minimum en route altitude far from the controlling facility then you’ve probably experienced loss of communications capability. This brings a whole new meaning to the idea of "lost comm." The radios are not really dead, but because of your aircraft’s position, line of sight to the communications outlet is lost. In this case you may need to think twice before squawking a radio failure emergency. If the loss of communications is due to the signal being obstructed by terrain then you don’t really have a radio emergency. As long as you are still on your route as cleared, you should regain contact at some point. One other myth about radio communications is that if the route between two navigation aids is charted (and as such we can expect to be able to receive navigation aids that define that route) that we should also be able to use voice communications along that route. Assuming that line of sight to the communications outlet is not obstructed, the aircraft’s radios still have to be strong enough to receive and transmit over that distance. Many radio sets are not capable of receiving much beyond 40-50 miles because of the calibration of the unit. We have seen old radios that performed even more poorly than this!

Myth number four says that since you’re going on instruments to your destination, you don’t need the visual charts on board. While the extra charts can be cumbersome to carry along, they can also be lifesavers in the event that a diversion to a visual airport is required.

Things to consider:

1. Visual airports won’t be listed or have airport diagrams in the instrument approach plate booklet.
2. Many important visual landmark features are left off instrument charts.
3. Airspace boundaries are not obvious on the instrument chart. One can think of many scenarios where having visual charts and information on board would be helpful. For instance, total loss of the electrical system is likely to put you "in the blind" in terms of location. Assuming you can get out of the clouds safely, having those visual charts will allow you to use pilotage to get to an alternate field.

One last and very insidious pitfall is assuming that it is safe to casually glance at the destination approach chart shortly before arrival. In fact, many instrument approaches are so complex that any one of a dozen small errors in chart interpretation can have disastrous effects. It is for this reason that thorough review of the destination and alternate airport approach procedures are recommended prior to departure. Not withstanding the departure, which may require a climb gradient beyond what your aircraft is capable of, arrival procedures may also exceed the capabilities of some light aircraft. For instance, using the ILS Runway 13 at Provo, Utah (U.S.) as an example, we see an approach procedure that is not only procedurally complex but requires expert management of the navigation radios to fly it successfully. This approach combines all the fun things that most of us try to avoid, into one dangerous looking approach (example: restricted airspace, mountainous terrain exceeding 11,000 feet MSL, hold and DME arc entry procedures and a missed approach procedure that reads like a Clancy novel). This is not the type of approach you can review 10 minutes prior to arrival and hope to fly safely. Some thought as to how to manage the radio setup is required. In addition, a thorough review of your aircraft’s performance is mandated. Just one example may not convince you that approach review should take place prior to departure, but experience has shown that unfamiliar approaches, such as this one, rank high in any risk assessment of a flight.

While instrument flight can be a rewarding and fun experience, it is full of potential dangers that can lure the unsuspecting pilot into nasty situations. It is important to look for the hidden dangers and understand how to deal with them. It is also important to know what procedures are the safest so the myths and pitfalls can be avoided. Hopefully we have dispelled some of these myths and alerted you to some of the pitfalls.