According to AIM 5.4.21(b):

When an early missed approach is executed [...] fly the IAP as specified on the approach plate to the MAP at or above the MDA or DH before executing a turning maneuver.

Hence if a pilot decides on a missed approach, he needs to wait until over the MAP to execute any turns on that procedure. One can only assume that is meant to prevent a climbing turn into a nearby protected airspace.

The following scenario puzzles me.

A pilot executes a LOC approach with a missed approach consisting of "Climb to 1000' then left climbing turn to 5000' direct to..." Sometime after the FAF the cockpit timer breaks. The MAP can no longer be identified by time. The pilot immediately starts climbing to 1000'. But when to start the left climbing turn to 5000'?

  1. The aircraft does not have other equipment that would positively identify the MAP, when is that pilot required to begin that turn?

  2. What if the aircraft has a DME? Is the pilot allowed to identify the MAP by distance rather than by time?


No, you can go missed anytime you feel you cannot complete the approach you are currently flying successfully. This includes anytime you are flying the final approach segment before reaching the VDP, if there is one, and all the way to the MAP at MDA.

A failure of a required piece of equipment needed to fly the approach properly would be a mandatory reason to execute a missed approach immediately. Doing otherwise is dangerous. Now if stepdown fixes can be identified by multiple means, then there is some redundancy, unless a piece of equipment eg DME, etc is specifically listed on the plate as required for the approach.

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  • $\begingroup$ AIM 5.4.21 specifically mentions the requirement not to fully execute a missed approach on a final approach segment until the MAP is reached. Climbs seem permitted, but turns are not. $\endgroup$ – mipnw Jan 10 '19 at 21:27
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    $\begingroup$ It would depend on what cause the need initiate the missed approach. In addition, unless comms are lost or some other reason, you usually will not fly the full missed approach procedure but will be handed over to approach controllers who will assign vectors. $\endgroup$ – Carlo Felicione Jan 11 '19 at 1:30

Well, I’m not an FAA guy so I can’t find the relevant FAR quote, but going more general:

ICAO Doc 8161 Vol 1 - Aircraft Operations I-4-6-1

6.1.4 Note 2

In the case of a missed approach with a turn at an altitude/height, when an operational need exists, an additional protection is provided for the safeguarding of early turns. When it is not possible, a note is published on the profile view of the approach chart to specify that turns must not commence before the MAPt (or before an equivalent point in the case of a precision approach).

There is a nuance difference between AIM’s “you are not supposed to turn” and the ICAO’s “if the turn area is not protected there must be a warning label”. The first is just procedural, the second ensures you will not hit a mountain.

  • If the missed approach only specifies ‘Climb 1000’ then climbing left turn to..’ then the airspace is protected even for early turns (between IAF and MAPt) and you can start turning as soon as reaching 1000’. It might get you in trouble with ATC (ie. they were not expecting you to do it), but it will not get you into a mountain side. If you can call ATC and explain that you are turning early because of a navigation/timing fault, you will be allright.

  • If there is also a ‘do not turn before [...]’ then you shouldn’t turn before, regardless if that fix is the MAPt or not. How to determine that fix or MAPt then becomes a navigation issue:can you use alternative methods? Gps? Dme? Vor radials? are you under radar contact? How about using the VSI climb rate to estimate 1 minute (climbing 700’ at 700 fpm). If neither, then you might be in an emergency situation.

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  • $\begingroup$ Thanks. Ok if it makes my question easier to understand you could interepret the same question with an added missed approach plate instruction that "turns must not commence before the MAP". I'm pretty sure that instruction does not need to be explicitly on the approach plate. You are not supposed to turn until you are over the MAP, AIM 5.4.21 (b). You cannot start turning upon reaching 1000' if you haven't reached the MAP, that is incorrect. Indeed it appears like my question yields => you are in an emergency situation. Several answers suggest so. $\endgroup$ – mipnw Jan 11 '19 at 10:33
  • $\begingroup$ And just as a side-note, I'm putting this into a comment: I cannot find any equivalent in EASA regulations for this , which means at least in EASA airspace, you are not expected to continue to MAPt $\endgroup$ – Radu094 Jan 12 '19 at 17:25

On Question 2: If there is a functioning DME on the airplane, and there was a DME signal that could be used, that is, a DME at the localizer or a DME at a VOR that is aligned with the approach path, yes you could use that, but it almost certainly the approach itself would be a VOR/DME approach and you would be using DME as primary anyway, with timing as a backup if the DME craps out.

If LOC only, your next best option would be to use a crossing radial from a nearby VOR as your primary MAP indication, and if there is one available it's usually depicted on the plate (then there's GPS of course).

You should always have a backup source for the MAP, so if it was LOC only with no nearby VORs and no GPS, so that timing is the only option, I would be using two stopwatches, or a stopwatch and my own watch as a backup.

Which gets us to Question 1: I was (theoretically) foolishly relying on single source timing and that is now gone, with no other source. Well, what else can you do but use common sense to do the best you can? Start counting down verbally from the seconds remaining when the stopwatch failed, and may add a few seconds extra just for kicks.

If you are well above MDA, you have lots of obstacle clearance margin for the missed approach procedure so it's not such a big deal to overshoot the MAP a little bit before you start turning (you could be executing a missed while in the middle of a circling maneuver at MDA on the other side of the airport, so overshooting the MAP a littl bit on final before climbing, even at MDA, is really not a big deal from that standpoint), so I would err on the overshoot side when implementing my best guess countdown. I'd be confident I wasn't going to run into anything.

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