When To Leave Final.
Airline pilots rarely get anything but vectors to an ILS. Even more rare with GPS approaches are VOR approaches. I still stay sharp on these non-precision approaches, however, thanks to my /A-equipped 1970's Piper Cherokee.
In the training for the airline, we frequently fly the VOR-B into Missoula, MT. It's a fairly straightforward approach, honestly. However, the descent rate after the final step-down fix (ERRIK) to the runway is quite steep to land straight in on Runway 30, even if a left base entry is made--about 3400 feet of altitude in about 6 miles. That six-degree descent rate wouldn't meet our stabilized approach criteria. Flying a left base makes the descent rate barely manageable.
Let's say the ceiling is at 4000 feet and we have the requirements of 91.175 met. When are we legally permitted to leave the final approach course (FAC), enter a left base, and begin final descent? Could we legally leave the FAC before ERRIK?
The airline pilot in me says that legally, a circling approach is a visual maneuver and it's technically legal to leave the FAC when you have 91.175 met. The CFII in me says that leaving the FAC outside of the TERPS circling radii is silly and possibly dangerous.
In the jet it's a catch 22. If we leave the FAC early, we can safely maneuver the airplane and be stabilized for an easy landing on 30 while maintaining visual terrain clearance (this is what they teach). If we stay on the FAC too long we risk either missing the approach or getting pressured into an unstable descent.
I'm not ruling out the technique that I'd do in the Cherokee, which is to fly the FAC over the threshold and enter upwind for a full left-traffic pattern. It's just a more difficult maneuver in the jet.
The regs have all sorts of guidance on when it is legal to leave the vertical profile of an approach. However, I can't seem to find any guidance on when it is legal to leave the lateral profile, i.e. the final approach course.
St. Louis, MO
We sent this over to Mark Kolber, our regs guru, and he replied:
There's no reg on when one can maneuver away from the FAC, and no formal General Counsel interpretations I'm aware of. But there is some related guidance in the Instrument Flying Handbook. Note the last two sentences:
"The circling minimums published on the instrument approach chart provide a minimum of 300 feet of obstacle clearance in the circling area. During a circling approach, the pilot should maintain visual contact with the runway of intended landing and fly no lower than the circling minimums until positioned to make a final descent for a landing. It is important to remember that circling minimums are only minimums. If the ceiling allows it, fly at an altitude that more nearly approximates VFR traffic pattern altitude. This makes any maneuvering safer and brings the view of the landing runway into a more normal perspective."
This is definitely not a legal opinion, but that tells me the obvious. The purpose of an IAP is to get you in position to make a normal landing and, the more normal the better. With your 4000-foot ceiling, I think we are in the neighborhood where some of the cases I listed in the circling article and the FAA's recent guidance on traffic patterns pretty much require IFR traffic to fit into the VFR traffic pattern. I'm not sure how you come to the conclusion that circling with a 4000-foot ceiling is potentially unsafe. I'd think exactly the opposite.--MK
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