December 8, 2016

Instrument rules: Differences between the U.S. and Canada


Instrument rules: Differences between the U.S. and Canada


The goal of instrument flying is the same no matter where in the world you do it; to get through the clouds or low visibility to a landing at the destination airport. Without it we’d be stranded on the ground, sometimes for days, waiting for the weather to improve.

Luckily technology, some of it pretty old, allows us to forge ahead through the muck. However, although the goal is the same, the rules from one country to the next are not always identical.

Granted, I’ve never found any rules that varied from the general concept of keeping pilots safe, but safety is a qualitative thing, and one regulatory body’s interpretation of how things should be done is not always the same as another’s. Sometimes there are differences in how airplanes are flown, the missions, the weather patterns, and terrain issues that require rules that might differ from one country to the next.

Regardless of the reasons, awareness of those differences is important. What follows is not an exhaustive look at the differences between the U.S. and Canada, but those that I’ve caught during my review.

During an instrument departure from an uncontrolled airport in Canada, it’s recommended that the pilot contact ATC if more than 60 minutes will elapse between the stated flight plan departure time and actual takeoff. Failure to do so leads to the SAR process being activated. In the U.S., if a clearance is issued for the departure from an uncontrolled airport, the pilot must contact ATC within 30 minutes of the clearance void time or else SAR procedures will be initiated. Also, there are few situations that allow for an IMC departures from an uncontrolled airport in the U.S. without a clearance since almost all departures would enter controlled airspace shortly after takeoff.

I understand there are places in Canada where the entire flight could take place in uncontrolled airspace, so a clearance is not needed prior to departure in those cases.

And since we’re talking about uncontrolled airspace, it’s a good idea to compare Class G airspace operating procedures. In Canada, it’s recommended that 126.7 be used to broadcast intentions during instrument flight. If the airport has a MF, the pilot shall broadcast intentions on 126.7 prior to switching to the MF indicated for approach and landing.

For departure, pilots should broadcast intentions on both 126.7 and the local MF prior to departure. In the U.S. there is no particular Class G airspace where the pilot would normally be flying en route, but certainly many “G” airports with instrument approaches. So there is no equivalent to 126.7 for instrument flight in the U.S.

All instrument flights would be in contact with ATC until needing to switch to the “MF”; referred to the CTAF (common traffic advisory frequency). Most uncontrolled airports in the U.S. have one of a myriad of discrete CTAFs, but in the case an airport does not, then 122.9 is the universal frequency to use.

As with Canada, in the U.S. it’s advisable to blindly broadcast intentions on the CTAF prior to landing and prior to departure.

When airborne, 8.3.2 of the Canadian Rules of the Air and Air Traffic Services en route procedures require a report when TAS at cruise or flightlevel changes more than 5% of that specified in the flight plan. Be aware that in the U.S. the rule also includes the caveat that a 10 knot change, if larger than 5%, is part of the reporting criteria.

This difference only becomes important if you are flying a fast aircraft. If you are relatively slow in the first place, then you’ll usually trip the 5% rule prior to reaching +/- 10 kts.

RAC 8.5.1 discusses recommended climb and descent procedures. Specifically, it indicates that “climb or descent should be made at the optimum rate consistent with the operating characteristics of the aircraft.” The FAA makes the same recommendation for climbs and descents in the U.S. but adds that ATC expects that climb to taper off, within the last 1,000 feet prior to level-off, to 500-1,500 feet-perminute.

Of course they also have a mandatory report if you are unable to maintain a 500 foot rate of climb or descent. It’s not clear that you must report if you desire not to climb or descend at 500 fpm, but everyone here is in general agreement that since ATC expects at least 500 fpm, if you don’t plan to give them at least that much, then you should let them know.

Sometimes it’s desirable to climb to visual conditions on top of a cloud layer. In Canada the request to do so is made by asking for “1,000 feet on top” IFR flight. Several restrictions apply when flying 1000 feet on top during an IFR clearance. When flying in the U.S. if a request is made using the Canadian “1000 feet on top” terminology, it might be confused with the “VFR-on-top” clearance that is commonly used to get on top of a layer.

Problems that could arise by not understanding the difference are:

1) In the U.S. there are no separation services with a VFR-on-top clearance, so pilots must see and avoid all other aircraft,

2) VFR cloud clearances must be adhered to, and those vary depending on the type of airspace you’re flying in,

3) There is no restriction on how well defined the tops of the cloud layer is under U.S. regs. If you think you’re on top, and you’re maintaining VFR conditions, then you’re good to go!

4) I’m not sure about the Canadian regs on this, but in the U.S., once you are VFR on top, you can cancel the IFR clearance and flight plan entirely and continue on your way, as long as you can stay in visual conditions of course!

During en route, and sometimes terminal operations, holding may be required. While general holding procedures do not differ between Canada and the U.S., some terminology does differ. First, on the rare occasion that holding pattern entry terminology is used by ATC, realize that a “teardrop entry” is the same as an “offset entry.”

The other two types of entries to a hold are referred to in the same way in both countries. The shuttle procedure is also a term that is not used in the U.S. In fact, I’m not sure we have any holds that are set up for descents or climbs in mountainous areas, although they certainly could be used for that should the need arise.

So if you fly down to the lower states and you need to descend or climb in a hold, ask for it in plain English because no one will know what a “shuttle” is!

Visual approaches are another area where rules differ between Canada and the U.S. Although they can be issued by ATC or requested by the pilot in the same basic ways in both countries, the minimum weather requirements differ. The U.S. visual approach generally requires at least VFR conditions (1,000 AGL ceiling and three miles visibility), while in Canada, 500 feet above the minimum IFR altitude, and three miles visibility is required.

While this difference is not important as far as ATC issuing a visual approach clearance, it may be important if the pilot is trying to request this type of approach.

We all know by now that landing out of an approach requires certain criteria to be met. Besides having the required visibility, visual references that would allow a safe landing are also necessary. Canadian arrival procedures 9.19.3 discusses landing minima, and those visual references that may be used to meet the requirements for continued descent to a landing from DH or MDA.

Further, the landing visibilities are considered to be advisory in that they provide the minimum visibility to be able to see the necessary airport visual references to safely land.

The U.S. rules for landing out of an approach differ in two important ways:

1) Parallel runway edge lights are not listed in FAR 91.175, which covers operation below DH or MDA. So seeing those lights, and not the landing runway references, would not be legal visual references in order to proceed with a descent out of DH or MDA in the U.S.,

2) In the U.S. the visibility must be at or above that listed in the approach minima, or else a landing cannot be made in the U.S. However, if the pilot should determine that the prevailing visibility is at least as high as the charted minima, upon reaching the DH or MDA, then that visibility may be used instead, and if the other necessary visual references are available, a landing can be attempted.

Canadian rules recommend advance notice of intent if a missed approach is likely due to poor weather conditions. This simply gives ATC some advance idea of what you’d like to do if you can’t make it into the airport.

While the U.S. has no such recommendation, it is probably a good idea to follow the same guideline. However, as it stands now in the U.S., if no missed approach instruction has been given, the pilot assumes that he or she is to fly the published missed approach procedure. Presumably, at some point during the miss, ATC would inquire as to the pilot’s intentions for completing the flight.

Rules do differ between the U.S. and Canada, and while this article gives a flavor of those differences, instrument flying is largely the same task in both countries. Still, a review of those subtle differences is always a good idea. One good resource for a more thorough review of U.S. procedures and recommendations is the FAA’s Aeronautical Information Manual and FAR part 91. Be sure to review these prior to instrument flight in the U.S.!

This month’s Pilot’s Primer is written by Donald Anders Talleur, an Assistant Chief Flight Instructor and Researcher at the University of Illinois, Institute of Aviation. He has been flying since 1984 and in addition to flight instructing since 1990, has worked on numerous research contracts for the FAA, Air Force, Navy, NASA, and Army. He has authored or co-authored over 200 aviation related papers and articles and has an M.S. degree in Engineering Psychology, specializing in Aviation Human Factors.