The Missed Approach: A Briefed but Rarely Flown Maneuver
The missed approach procedure may be one of the most briefed and least flown maneuvers that instrument-rated pilots accomplish. A pilot briefs the missed approach procedure each time they execute an instrument approach but is rarely required to fly one. To maintain proficiency, instrument-rated pilots and those in instrument training are required to practice executing the missed approach. Often, the maneuver is practiced upon arrival at the missed approach point – either DA (decision altitude) or the MAP (missed approach point) at MDA (minimum descent altitude). This tactic is sound because in real-world flying, arrival at the missed approach point is likely where the missed approach procedure begins.
When the Missed Approach Must Start Early or Late
But what if arrival at the MAP is not where the pilot needs to start the missed approach? What if going missed is required early? Or late – below MDA or DA? The AIM spells out procedures for some of these occasions but lets start with understanding how flying the published missed approach procedure keeps the aircraft clear of obstacles and on a safe path toward the next step.
FAA Standards for Missed Approach Obstacle Clearance
Before an instrument approach is certified the FAA TERPS (US Standard Terminal Instrument Procedures) team calculates required terrain and obstacle clearance based on a set of standards. The AIM gives us a clue to those standards – see below:
“Obstacle protection for a missed approach is predicated on the missed approach being initiated at the decision altitude/decision height (DA/DH) or at the missed approach point and not lower than minimum descent altitude (MDA). A climb gradient of at least 200 feet per nautical mile is required, (except for Copter approaches, where a climb of at least 400 feet per nautical mile is required), unless a higher climb gradient is published in the notes section of the approach procedure chart.
When higher-than-standard climb gradients are specified, the endpoint of the non-standard climb will be specified at either an altitude or a fix. Pilots must preplan to ensure that the aircraft can meet the climb gradient (expressed in feet per nautical mile) required by the procedure in the event of a missed approach, and be aware that flying at a higher than anticipated ground speed increases the climb rate requirement (feet per minute). Tables for the conversion of climb gradients (feet per nautical mile) to climb rate (feet per minute), based on ground speed, are included on page D1 of the U.S. Terminal Procedures booklets.”
Key Takeaways from the AIM on Missed Approaches
(1) The missed approach clearance corridor begins at the MAP, be it DA or MAP at MDA.
(2) The required climb is the standard climb rate for instrument – 200fpnm.
(3) If a higher climb gradient is required, it will be listed on the chart.
What If You Need to Go Missed Before the MAP?
What if the pilot decides to execute the missed approach procedure prior to arrival at the MAP? The AIM addresses this scenario as well –
“Reasonable buffers are provided for normal maneuvers. However, no consideration is given to an abnormally early turn. Therefore, when an early missed approach is executed, pilots should, unless otherwise cleared by ATC, fly the IAP as specified on the approach plate to the missed approach point at or above the MDA or DH before executing a turning maneuver.”
Restated, if the pilot is required to go missed prior to arrival at the missed approach point they should continue the lateral course guidance until reaching the MAP and then begin the missed approach as turning on course early may pose a collision hazard. Makes sense, right? The pilot can begin the go around procedure and start the climb early, but no turns until after the MAP.
Executing a Missed Approach Below MDA or DA
Seems simple enough, but what if a missed approach is necessary after descent below MDA or DA like in the case of an unstabilized approach or a vehicle on the runway?
The missed approach procedures on the approach plate are designed for executing the missed at the MAP. Missed approach execution below MDA or DA does not align the airplane on the same vertical path as the published missed approach. How can the pilot ensure that the climb rates can be met and that the airplane will be clear of terrain and obstacles?
Incorporating Departure Procedures for a Safe Climb-Out
One method is to brief any departure procedures or takeoff minimums for the desired runway as part of the missed approach brief. This technique ensures that all climb rates can be met during the missed approach procedure.
Lets look at takeoff minimums for KLUK. If we read the takeoff minimums for runway 21 we can see that the greatest climb gradient required for departure is 439 fpnm.
Assuming a 100KIAS groundspeed, that equates to a 732 fpm climb required. If the pilot went missed after arrival at the MAP, climbing at least 732 fpm will keep the aircraft clear of terrain and obstacles. Incorporating this required climb rate in to the brief is recommended to ensure a safe climb out if a late executed missed approach is necessary.
A safe pilot is ready to execute the missed approach at any time when transitioning to the terminal environment of an airport. Proper flight planning and approach briefing ensures that no matter where the missed approach decision is made, the procedure can be executed safely.
Make good choices.
