Danger lurks in circling approaches
Air Facts Journal

Asheville airport

the circling approach maneuver is designed as a last resort, non-precision approach.

The very first question that should pop up into our head during a circling approach is “Why are we circling in the first place”? The next one is “What are our other options?” This should be followed shortly by even more questions:  “How truly important is it that we accomplish this now? What’s the risk vs reward? Are there advantages to waiting?”

Let us not forget that the circling approach maneuver is designed as a last resort, non-precision approach. A circling approach is one that, by dwindling numbers and its inherent design, forces the pilot(s) into a seldom used and high-risk evolution–often migrating us to an unexpected and seldom visited zip code of the threat/error management neighborhood.

Yep, we may see one of these in our initial or even recurrent training (one that is presented in a controlled, safe environment to only a couple of simulator-approved airports like KMEM and KJFK). Yet, anybody in their right mind will not volunteer to execute a circling approach when other options are available. Practicing/demonstrating a circle to land at an airport that one likely never will utilize is well, nonsensical at best.

Let us revisit the design of these Circle-to-Land approaches. The approach is designed with a mindset/expectation that the visual circling maneuver portion of the approach will be executed exactly as depicted on the chart (a circling approach is essentially a visual approach and gives the pilot(s) various options beyond what is depicted on the chart). The HAA (height above airport) is one that by design is biased on operational necessities along with the assumptions of four very salient and important cornerstones.

  1. A perfectly good airplane with everything operating as expected.
  2. A high degree of pilot proficiency, competence as well as currency (currency in Circling Approaches specifically).
  3. A known degree of familiarity with the airfield and surrounding terrain.
  4. An acceptable meteorological combination of ceiling, visibility, and wind.
Circling chart

ICAO minima for circling approaches is much higher than that stipulated in the FARs so consider higher weather minima.

Two additional notes of caution:

  1. ICAO minima for circling approaches is much higher than that stipulated in the FARs so consider higher weather minima (especially visibility and wind) than what is published as a proactive mitigation.
  2. A circling approach is a high-risk, low frequency event that it MUST be briefed.

No rushing through this scenario – no “John Wayne” procedural inventions or last -minute inspirations.

For purposes of our discussion, let’s break down this seldom-flown evolution into three phases: Mission Planning and Pre-Approach Briefing, Execution of Approach, and (if necessary) Missed Approach.

Mission Planning (prior to flight) and Pre-Approach Briefing (once airborne)

  • The more we front load, the better off we will be when the call comes to perform and deliver. Many of these options should be reviewed ahead of time, allowing us to familiarize ourselves with the expected tasks, options, parameters, and obligations.
  • While we do not want to rush or curtail the briefing, we do want it fresh on our minds. We also benefit from the latest weather updates. Perhaps just prior to the start of descent could be the optimum time–certainly completed no later than commencement of approach.
  • If we find ourselves rushing or cutting corners to complete the briefing, we most likely need to ask for vectors or holding to consider all the factors.
  • How truly important is this current approach to mission success?
  • When was the last time either pilot (single pilot) performed this exact approach?
  • Any NOTAMS applicable? Any aircraft inoperative items to consider?
  • What is the expected fuel burn? (‘Betcha is higher than you think)
  • What, if any, are the additional guidance and expectations for NIGHT circling approaches?
    • A proactive policy may very well be to prohibit night circling approaches
  • Weather updates?
    • Especially critical are visibility (orientation/depth perception), wind direction and velocities gusts.
  • There is a possibility of contamination such as icing/snow so it might be a good idea to review aircraft limitations on the subject. For example, some aircraft limit flaps and gear in icing until on approach or forbid the use of speed brakes or require a minimum thrust setting.
  • Particular attention to true airspeed vs. turn radius. (Higher TAS = different category aircraft = higher MDA) A higher TAS does yield a larger turn radius, even in the same aircraft approach category.
  • Specific discussion to neighboring terrain features such as buildings, towers, hills, trees. Where are the protected lateral radii?
  • New cicling

    Circling approach protected areas.

    What techniques will be utilized to comply with those obstacle radii? Outside of assessed radii, the MDA is no longer valid. If you depart MDA on the downwind or base leg, you’re on your own as far as obstacle clearance.

  • Recall that we must remain at or above MDA until we are in a normal position to perform a normal rate of descent to landing. How is this determined without vertical guidance?
  • What is the calculated landing distance?
  • What is the runway lighting? VASI? PAPI? (Only accurate within 10 degrees of runway heading).
  • If you choose to fly a Circle-to Land approach to a runway without a VASI or PAPI, you are greatly increasing your vertical flight error path (possibility/probability). This is easily compounded in aircraft equipped with older avionics packages with limited screen presentations/displays.
  • Who flies visually, and who monitors instrument data?
  • Which way is the procedure turn – left or right? Who then flies and who monitors?
  • Consider the following as a proactive technique: “The pilot who sees the runway in the turn, should be the pilot who flies the approach.
    • An additional useful technique is to have the Pilot Monitoring attend to the throttles & manage IAS. Once again, everyone must be “on the same page of music”…
    • What is expected of the pilot flying? What is expected of the pilot monitoring?
    • Effective, timely, concise communication is the key.
  • Is the airport have an operable FAA tower or is it an uncontrolled field environment?
  • A well briefed “transfer of aircraft controls” is paramount.
  • Non-towered airports greatly raise the possibility of traffic conflicts.
  • What specific indicated airspeed will be flown/adhered to during the circling maneuver? What speed on final approach? Will the vertical speed necessary comply with required descent criteria? What are the possibilities of a GPWS activation? What procedures will be followed in the event of a ground proximity warning?
  • At what AGL altitude will the aircraft be in a stable/configured condition? (No later than). Be fully configured and on speed prior to receiving landing clearance.
    • FAA parameters are no lower than 500’ AGL for stabilized criteria
  • What specific runway lighting do we expect to see?
  • What are the criteria for a Missed Approach Command?
  • Is the Missed Approach altitude at or above the MDA?
  • Are there any applicable second segment climb requirements?
  • What specific lateral track will be flown in the event of a missed approach?
  • How will this differ if you are past the missed approach point when you execute the go-around?
  • “Chair fly” techniques to circle at a non-towered airport (for example, what happens if you are too high and unable to execute your originally envisioned circling plan? What is your backup circling maneuver?)

 

Execution of Approach

  • Mentally stay ahead of aircraft if loss of situational awareness occurs–ANNOUNCE IT–speak u –secrets will not be to your benefit.
  • Work your hardest at maintaining an accurate lateral track. Remember higher airspeeds = larger turn radius.
  • Speed should be target (Vref) + 10 kts, in full landing configuration until the final approach segment. Then, transition to Vref + 5 kts + ½ the wind gust. Note that this adjustment may be aircraft specific as some manufacturers use other additives or no additives at all.
  • A common technique used in past times is to correlate the GS to target vertical speed. This will work well up to about 10 kts of headwind. The rule of thumb is VSI = ½ groundspeed times 10.
    • GS = 90 VSI= 450 FPM
    • GS =100 VSI= 500 FPM
    • GS= 120 VSI= 600 FPM
  • This is a great technique for the pilot monitoring to help the pilot flying to call out the VSI as the turn to final is made.
  • Another valuable technique is that once you are within 45 degrees of final rollout, request tower to “turn up” the runway lights. Once you see the change in illumination, you have another confirmation that you are where you’re supposed to be.
  • Strive to be wings level and on the correct rollout heading with an acceptable rate of descent as close to 500 feet AGL. While this is the normal FAA requirement, some circle to land approach profiles will place the aircraft slightly below 500 feet at MDA.
  • Use automation to your benefit as each pilot has their own comfort level. The use of automation can lead to a significant reduction in workload. Then again, if you lose your situational awareness to what the automation is doing (also known as mode awareness), you have dug yourself a deeper hole at the critical time when you can least afford it. Personally, I would hand fly the turn to final (once leaving MDA). Bottom line:  let there be no doubt in your mind as to the capabilities of your automation.
Low approach in Pilatus

Use automation to your benefit as each pilot has their own comfort level.

Missed Approach

  • When in doubt, go around–no question about it!
  • Much better to sing “Glad we did rather than sure wish we had.”
  • Prioritize getting away from the dirt and stay within the obstacle radii as you establish yourself on a published portion of the missed approach.
  • Are we executing the correct Missed Approach Procedure? Know where you are going before you get there.
    • Confirm that the Missed Approach Altitude is at or above the Minimum Vectoring/Sector Altitude

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