100LL,
I'm not sure they left out the prohibition against starting the final segment with the weather below minimums; 135.225(a) prohibits beginning the proceedure if the weather report is below minimums.
Where it falls short is addressing what to do if the weather goes down after beginning the approach.
The permissive and omissive nature of the language of regulation dictates that where something is not specifically prevented, it is allowed. In this case, one is prevented from beginning the approach if the weather is below minimums. Because no prohibition exists against continuing if the weather goes below minimums after starting the approach, then it becomes permissive in nature. In other words, while one cannot begin an approach below minimums, if it goes down after starting the approach, one is not prevented from continuing.
In the case of conducting the approach to an airport without approved weather (ie, eligible on-demand operations), a greater prohibition exists, namely that this opportunity of continuing is withheld until crossing the FAF.
I think what you're looking for isn't so much missing, as not adequately clarified in the language of the regulation. It's there, just not as well as it could be.
You bring up an interesting point, which was why the language of what to do upon reaching DH/MDA was included in this section...after all, that's more a landing issue than the approach issue. An approach naturally terminates in either a landing or a missed, and a landing must begin with an approach. The language of the regulation is a long way of saying "allowed to take a look-see." I believe the paragraph regarding pilot option upon reaching minimums on the approach is included to fully convey the concept that the pilot is allowed to fly the approach and see if the weather is above minimums. It also makes clear that merely because the regualtion permits the elible on-demand operator to continue with the weather being reported down, inside the FAF, the pilot is NOT allowed to continue past minimums unless it has come up or is up upon reaching approach minimums on the approach.
In reading the regulation as it presently stands, again, I'm not seeing any prohibition against continuing the approach at any point, for non-eligible-on-demand operations, once the approach has begun, if weather drops below minimums. In other words, one cannot begin the approach if weather is below minimums, but where the old language allowed one to continue after the FAF if weather went down, the new language doesn't prevent it at any time after the approach has begun. The new language may said to be more liberal.
Where the new language is more specific that this opportunity exists (to continue to minimums and have a look) is only to fields that require eligible on-demand authorization, as spelled out in 135.225(b),(c), and (d).
As I read this regulation more and more, I don't see anything preventing a pilot from beginning the approach under 135.225(a) because the reported weather is at or above authorized landing minimums, and then continuing if reported weather drops below.
We all know that weather can go up and down and be better than reported on arrival because of ragged ceilings, shifting low clouds, drifting fog, etc. Even frosted transmissiometers or celiometers...flying the approach to see if we break out isn't uncommon, where allowed. Accordingly, the language of 135.225(a) tells us we can't start the approach if the weather is down, but doesn't prevent us from flying the full proceedure once we've already started, should the weather suddenly go down. Essentially, it permits similiar liberties to a Part 91 approach only, except that we can't actually start the approach if weather is reported below minimums. Once begun, we are not prevented from continuing.
As I read it, I believe the only real restrictions here apply to eligible on-demand operations to airfields with limited or no weather reporting capability. This makes sense.
DC8Flyer asked:
Curious question for part 121 ops. You cannot continue an approach, if, while outside the FAF weather (vis that is) drops below minimums. So lets say for the sake of argument, you are being vectored below the GSIA you are inside the published FAF (maltise cross) but have not intercepted the glide slope yet. Tower calls and says the vis is down to 1/4 mile. Can I continue the approach?
Flx57 pointed out that you haven't reached the FAF if you're being vectored inside the published FAF (below GSIA), and haven't yet intercepted the glide slope. If you're being vectored below the published glide slope intercept altitude, the FAF occurs when you intercept the glideslope at that altitude. Accordingly, if you aren't on the glideslope yet, but are beneath it, then you haven't reached the FAF.
With this in mind, 121.567 provides that your approach limitations are provided by the certificate holders OpSpecs:
§ 121.567 Instrument approach procedures and IFR landing minimums.
No person may make an instrument approach at an airport except in accordance with IFR weather minimums and instrument approach procedures set forth in the certificate holder's operations specifications.
121.613 prevents departing if weather will be below minimums at ETA:
§ 121.613 Dispatch or flight release under IFR or over the top.
Except as provided in § 121.615, no person may dispatch or release an aircraft for operations under IFR or over the top, unless appropriate weather reports or forecasts, or any combination thereof, indicate that the weather conditions will be at or above the authorized minimums at the estimated time of arrival at the airport or airports to which dispatched or released.
The meat and potato(e)s of your question, however, are found in 121.651...which has also undergone some changes.
If you're flying an approach to a runway served both by PAR and an ILS, you may begin the final approach segment with the weather already reporting below category 1 minimums, so long as both the ILS and PAR are operative and used, and the proceedure isn't Cat II or III. Note that it also contains landing details that go beyond mere approach authorizations, essentially reiterating 91.175 with respect to requirements to go below minimums (which I have ommitted for brevity):
d) A pilot may begin the final approach segment of an instrument approach procedure other than a Category II or Category III procedure at an airport when the visibility is less than the visibility minimums prescribed for that procedure if that airport is served by an operative ILS and an operative PAR, and both are used by the pilot. However, no pilot may continue an approach below the authorized DH unless the requirements of § 91.175(l) of this chapter, or the following requirements are met:...
The prohibition against beginning the final approach segment, to which you referred, if the weather is below applicable minimums, is found in 121.651(b):
(b) Except as provided in paragraph (d) of this section, no pilot may continue an approach past the final approach fix, or where a final approach fix is not used, begin the final approach segment of an instrument approach procedure -
(1) At any airport, unless the U.S. National Weather Service, a source approved by that Service, or a source approved by the Administrator, issues a weather report for that airport; and
(2) At airports within the United States and its territories or at U.S. military airports, unless the latest weather report for that airport issued by the U.S. National Weather Service, a source approved by that Service, or a source approved by the Administrator, reports the visibility to be equal to or more than the visibility minimums prescribed for that procedure. For the purpose of this section, the term "U.S. military airports" means airports in foreign countries where flight operations are under the control of U.S. military authority.
The authorization to continue if the weather goes down after the FAF is found in 121.651(c), as follows (again, edited for brevity):
(c) If a pilot has begun the final approach segment of an instrument approach procedure in accordance with paragraph (b) of this section, and after that receives a later weather report indicating below-minimum conditions, the pilot may continue the approach to DH or MDA. Upon reaching DH or at MDA, and at any time before the missed approach point, the pilot may continue the approach below DH or MDA if either the requirements of § 91.175(l) of this chapter, or the following requirements are met:...
To sum that part up, unless you have company authorizations to the contrary, and unless an ILS with PAR is available and used, you can't begin the final approach segment if the weather isn't above applicable mins, and if it goes below after the FAF, you may continue to have a look with the standard requirements established to go below MDA/DA/DH. If you're being vectored below the glideslope intercept altitude (GSIA) and have not yet intercepted the glideslope, you are outside the FAF, and the permission to continue as specified in 121.651(c) doesn't apply to you.
Remember that while ICAO defines the final approach segment as "That
segment of an instrument approach procedure in which alignment and descent for landing are accomplished," the FAA defines it as "
The segment between the final approach fix or point and the runway, airport, or missed approach point." (Pilot-Controller Glossary). The FAA's terminology is more restrictive, and applies specificially to operations from the FAF-inbound.
