Autopilot Coupled Missed Approaches

For most GA instrument pilots, the event that causes the most surprise and stress is an unexpected missed approach.  Don’t we all just make the automatic assumption when we listen to the METAR and hear the ceilings reported above the MDA or DA that we will see the runway?  With that glass half full mindset, arriving at the minimums and not seeing the runway can be quite a surprise, leading to possible unsafe operations below the MDA or DA.  Having an autopilot that can handle the missed approach flying while the pilot cleans the plane up can be an excellent resource.

First, a note on mindset.  In IFR training, I teach pilots personal minimums.  I want all my customers to set ceiling and visibility personal minimums that are above the MDA or DA to help with the go/no-go decision.  Most of my customers have personal minimums in the 600-1000 AGL range and 2-6 mile visibility range.  Those are good, safe numbers that give wiggle room above most minimum altitudes on approaches.  Going into the mountains, these personal minimums need to change due to the fact that a lot of mountain approaches have very high minimums, sometimes in the 2000-3000 AGL range.  These approaches also have much more complex missed approach procedures.  I would recommend a 5000 AGL ceiling personal minimum for anyone going into Aspen, Eagle, or Heber, Utah.

With personal minimums in a pilot’s (electronic) flight bag, this leads to a mindset shift when listening to a METAR.  First, if the ceiling is below the pilot’s personal minimums, some pilots call off the approach and go to the alternate.  If the pilot isn’t quite that cautious, but the AWOS is reporting ceilings below 500 AGL but above minimums, I teach my customers to plan on going missed.  If the mindset is, “I’m going to be flying the missed approach”, then a pilot is much more prepared for the missed approach procedure.  Then, if the runway comes into view above the MDA or DA, it’s much easier to a pilot to adjust the mindset from missed approach to landing, rather than vice versa.  Plus, pilots “get on their game” if you will, when a “real deal” approach is being conducted and a missed approach is planned for.

Now, onto autopilots.  In a Cirrus with the GFC 700 autopilot and anything equipped with a Garmin GFC 500 or 600 autopilot, pushing the Go Around button at the minimums leaves the Autopilot coupled.  It does not shut off.  This technology has also made it’s way into most airplanes that have the G1000 NXi (I flew a TBM earlier this week where the autopilot stayed coupled when the Go Around button was pushed).  The Flight Director pitches up to a climb pitch attitude and goes into GA mode, keeps the wings level, then the pilot just has to add power, clean the plane up and press the NAV button on the AP controller.

One common autopilot that has become popular in the last 10 years is the Avidyne DFC 90 autopilot.  This is a great autopilot as it’s a slide in replacement for the STEC 55x, which was not a great autopilot.  The DFC 90 is a digital autopilot certified for the Cirrus, Beechcraft Bonanzas, the Cessna 182 and the Piper PA46-350P Mirage and PA46-350T Matrix.  The autopilot utilizes a digital signal from either a Garmin G500/G600 TXi, Avidyne PFD or an Aspen PFD.  It is not compatible with the Garmin G1000.

There is no Go Around button for the Avidyne DFC 90, but there is a way to stay coupled when flying a missed approach.  All autopilots are programmed to follow a glide slope and not level off, which means, even if the pilot puts an altitude in the Altitude Select box, altitude capture will not arm when the autopilot is in GS mode.  Basically, if the AP is flying a glide slope, it will fly the airplane into the ground unless the pilot stops it.  

The trick on the DFC90 is just above the MDA or DA, push the ALT button on the AP controller to capture whatever altitude the plane is at.  The autopilot then levels off the airplane, but stays in the lateral NAV/APPR mode.  The pilot then has to add power so as not to stall, clean the plane up (flaps and gear), then, based on whatever GPS unit is installed, activate the missed approach procedure.  Since the autopilot is still in NAV/APPR mode, once the missed approach procedure is activated, the autopilot will keep tracking the course.  The pilot then engages IAS mode and sets the missed approach altitude in the altitude select box, and away it goes.  

A lot of glass panel airplanes have the ability to input minimums somewhere on the PFD.  Always do this because when the airplane reaches the minimums that are input, a verbal call will come through the headset saying “minimums!”.  This is the cue to press the Go Around button (Garmin Autopilot) or push the ALT button (Avidyne DFC90).  

One note:  all early G1000 airplanes that had the GFC 700 autopilots (with the exception of the Cirrus) do not stay coupled when the Go Around button is pressed.  So, for those Cessna, Mooney, Beechcraft and Piper owners who have the legacy G1000 units with the GFC 700 Autopilot installed, pushing the Go Around button turns off the autopilot and the pilot must start hand flying the airplane.  Be Ready!

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