When should the missed approach procedure be executed?

Question

When flying a straight-in precision or non-precision instrument approach, when should the missed approach procedure be executed?

Note that this is being asked in the context of FAA regulations, but ICAO answers are also welcomed. Understanding the overlap or differences is also appreciated.

Example 1

While flying the KLEX ILS 22 you find yourself 3.0 DME at 1900 MSL. You call missed and begin climbing. A moment later you are passing 2000 MSL and 2.8 DME. When do you begin your the missed approach procedure, specifically the left turn direct HYK for the hold?

Let's add another scenario to example 1, what if you were give alternate instructions of climb to 1000 then climbing left turn to 270, climb to 3100? Would that change anything about when to execute the turns in the missed approach procedure?

This example is a precision approach. It is also specifically a situation where the aircraft is going missed well before DA/DH. And it includes a second portion where alternate missed approach procedure has been provided by ATC.

Example 2

While flying the KLEX LOC 22 you pass the FAF BRIDL at 3200 MSL. You descend to 1520 and level off where you remain in IMC with no visual references. When do you begin the missed approach procedure?

This example is a non-precision approach. It assumes that the approach is continued at MDA and visual references will not be seen.

Answer 1

You should start your turn at the MAP. A little after is also fine- you are protected for the distance required to climb from DA to 2000 feet from the MAP at 200 fpnm- approximately 3.1 nautical miles past the runway threshold, in this case.

In scenario 1, by going missed early you've left yourself no way to identify the MAP. Whoops! If you had timed the approach, you could have used the time to MAP table on the chart- though this is for the LOC MAP and about .7nm past the ILS MAP, it doesn't provide you any worse obstacle separation all of a sudden just because you were using the glideslope.

In scenario 2, the only way the MAP is identified is by distance from the FAF, and you need to time the approach, and not turn until after the time has elapsed.

Remember that in both cases you will need to do some calculations if you change your groundspeed while going missed early.

Answer 2

Example 1

When executing an early missed approach, the aircraft should continue on that segment of the approach until reaching the point where flying the slideslope would have reached DA/DH, or the MAP for that approach, before beginning any turns associated with the missed approach procedure. In this case the aircraft went missed at 1900 and needed to reach 2000 to begin a turn, so two conditions must be met before making the left turn direct HYK for the hold: above 2000, and having reached the MAP.

The same is true in Example 1 if alternate missed instructions were given. The aircraft should continue to the MAP before executing a turn.

This does not rule out the possibility that ATC gives vectors when you report going missed. The AIM also states that vectors should be followed if given by ATC when the missed is reported.

There is some ambiguity in terms of identifying the point where the aircraft would have reached DA/DH had the glideslope been followed. In the case of this approach, that point does not coincide with an identifiable DME or fix. This is a good reason to time all approaches. Navigation equipment vary from aircraft to aircraft, but generally TOGA or pressing a SUSP button will cause IFR certified GPS units to release the required inhibition of sequencing into a missed approach. The lateral track of the final approach segment that you're already on will continue to be tracked until reaching the point programmed into the GPS. If available, I believe this is the most accurate way to identify the MAP on a precision approach.

Example 2

Another reminder to time all approaches. Continue either until the time associated with your groundspeed has elapsed, or other means of IFR certified navigation are available as mentioned in my answer for Example 1. Continue on the approach until reaching the MAP before making any turns. Climb to the missed approach altitude is permitted at any point that a missed approach is executed.

References

AIM 5-4-21

Obstacle protection for 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).

Instrument Flying Handbook 10-21

If the missed approach is initiated prior to reaching the MAP, unless otherwise cleared by ATC, continue to fly the IAP as specified on the approach chart. Fly to the MAP at or above the MDA or DA/DH before beginning a turn.

Answer 3

When you see the chart with Times and Speeds at the bottom of an approach, that means its a timed approach. The instrument needed is a clock, which is required in all IFR certified and legal aircraft.

The answer to your question in both scenarios is printed on the bottom of the approach plate next the the times and airspeeds. It reads FAF to MAP is 6.6NM. The missed approach point is 6.6NM from the FAF (near runway threshold). You are permitted to start the climb early when performing a missed approach but not the turn. The turn must wait until reaching MAP.

You should be hitting start on your clock at the FAF for timed approaches.

In scenario #1, you started climbing early, you won't be able to use DH/DA as the point where you begin the missed approach, so you can use either the TIME for your appropriate approach speed, or if equipped, GPS to identify 6.6NM from the FAF. Keep in mind that to use TIME you would need to be climbing at the approach speed you were using. So if your approach speed is 90 kts (and you're using 4:24 min), you would need to be climbing at 90 kts for the TIME in the chart to accurately reflect the location of the MAP.

In scenario #2, you're supposed to start the clock at the FAF, that is the only way to identify the MAP if you don't have GPS. However, if you have GPS, it will identify the MAP point for you, that is where you should start the climbing left-hand turn if you're already at or above 2000 ft.

In conclusion, the MAP for this approach is 6.6NM from the FAF. It can be identified by the DH/DA on the ILS, TIME, or GPS if so equipped.

Answer 4

Example 1: Per the missed approach procedure, you would start your left hand turn at 2000 ft. As long as the aircraft is either on the localizer or localizer back course, this should provide obstacle clearance for the immediate climb out. At 2000 feet you can begin a turn toward the Lexington VOR/DME, climbing up to the Minimum Sector Altitude, which provides obstacle Clearance within a 25 mile radius of Bridl LOM. As to a missed procedure specified by ATC, you would simply follow the instructions of ATC.

In Example 2, your MAP would be the threshold of runway 22, as specified on the plate.