Flight Visibility on non-precision approaches
05-08-2024, 04:41 PM
#12
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Joined APC: Aug 2006
Position: 1559
Posts: 1,534
Originally Posted by JohnBurke
If you're at minimums, your only concern is 'do I see the runway environment and can I descend from MDA?' If you have the approach lights, you can descend 100' below, and if you have the runway, come on down. That's not the time to be guessing what the visibility is. You needed the appropriate legal visibility to start the approach. To finish it, you need to be able to see the runway environment.
05-09-2024, 06:30 PM
#14
Prime Minister/Moderator
Joined APC: Jan 2006
Position: Engines Turn Or People Swim
Posts: 39,393
Originally Posted by MX727
All, good, but it's not 100' below mins, it's down to 100' AGL.
Originally Posted by Rama
JB is correct that having the approach lights in sight allow you to continue below MDA.
You need a ground reference to continue below 100' AGL, you need to see more than just the approach lights.
You need a ground reference to continue below 100' AGL, you need to see more than just the approach lights.
The 100' below mins is a common misconception since your typical CAT I has a DA which equates to 200' AGL... so 100' below that is the same as 100' AGL.
05-09-2024, 06:48 PM
#15
Disinterested Third Party
Joined APC: Jun 2012
Posts: 6,074
One can continue to one hundred feet, but that wasn't really the point.
The point was that one does not need to have, or verify, approach weather minimums (ceiling or visibility) when approaching minimums. What's being reported isn't nearly as important as what's outside the window. One is looking outside, or half-in-half-out, depending on one's role for the approach, and at such time as one looks up and sees the required visual references (and acknowledges them, as one's SOP may dictate ("continue," "landing, etc), one isn't asking at that moment in time if the current, up-to-the-second weather is still reporting above minimums, because one is inside the FAF/GSIA and looking for visual references. Those references may be the runway, or simply pre-runway references that allow one to descend a little lower, until one acquires the runway (or must go around).
That was the point. The question regarded whether one must have legal reported weather minimums, when arriving at minimums, and the answer is that one has what one sees out the window, at that point. It was noted by some that one should have the charted (or approved; eg, OpSpec, etc) minimums, but this is not correct. Those were needed to begin the approach; arrival at MDA on a constant descent approach, or DH/DA, one isn't going to (and shouldn't) check weather to see if there are changes; one is looking for the necessary visual references (Except cat III procedures when one may not see the runway before touchdown). So long as the necessary minimums were reported in order to begin the final approach segment, that element of the approach has been satisfied. Upon arrival at minimums, what's seen out the window is the order of the day. What's required and the altitude to which we can go depends entirely upon the procedure, the nature of the approach, in some cases the aircraft, in all cases of certificate holders, the certificate holder's approvals and authorizations, and of course, also the pilot and his or her qualification (and currency).
The point was that one does not need to have, or verify, approach weather minimums (ceiling or visibility) when approaching minimums. What's being reported isn't nearly as important as what's outside the window. One is looking outside, or half-in-half-out, depending on one's role for the approach, and at such time as one looks up and sees the required visual references (and acknowledges them, as one's SOP may dictate ("continue," "landing, etc), one isn't asking at that moment in time if the current, up-to-the-second weather is still reporting above minimums, because one is inside the FAF/GSIA and looking for visual references. Those references may be the runway, or simply pre-runway references that allow one to descend a little lower, until one acquires the runway (or must go around).
That was the point. The question regarded whether one must have legal reported weather minimums, when arriving at minimums, and the answer is that one has what one sees out the window, at that point. It was noted by some that one should have the charted (or approved; eg, OpSpec, etc) minimums, but this is not correct. Those were needed to begin the approach; arrival at MDA on a constant descent approach, or DH/DA, one isn't going to (and shouldn't) check weather to see if there are changes; one is looking for the necessary visual references (Except cat III procedures when one may not see the runway before touchdown). So long as the necessary minimums were reported in order to begin the final approach segment, that element of the approach has been satisfied. Upon arrival at minimums, what's seen out the window is the order of the day. What's required and the altitude to which we can go depends entirely upon the procedure, the nature of the approach, in some cases the aircraft, in all cases of certificate holders, the certificate holder's approvals and authorizations, and of course, also the pilot and his or her qualification (and currency).
05-10-2024, 01:48 AM
#16
Gets Weekends Off
Joined APC: Jan 2008
Posts: 1,224
Originally Posted by JohnBurke
One can continue to one hundred feet, but that wasn't really the point.
The point was that one does not need to have, or verify, approach weather minimums (ceiling or visibility) when approaching minimums. What's being reported isn't nearly as important as what's outside the window. One is looking outside, or half-in-half-out, depending on one's role for the approach, and at such time as one looks up and sees the required visual references (and acknowledges them, as one's SOP may dictate ("continue," "landing, etc), one isn't asking at that moment in time if the current, up-to-the-second weather is still reporting above minimums, because one is inside the FAF/GSIA and looking for visual references. Those references may be the runway, or simply pre-runway references that allow one to descend a little lower, until one acquires the runway (or must go around).
That was the point. The question regarded whether one must have legal reported weather minimums, when arriving at minimums, and the answer is that one has what one sees out the window, at that point. It was noted by some that one should have the charted (or approved; eg, OpSpec, etc) minimums, but this is not correct. Those were needed to begin the approach; arrival at MDA on a constant descent approach, or DH/DA, one isn't going to (and shouldn't) check weather to see if there are changes; one is looking for the necessary visual references (Except cat III procedures when one may not see the runway before touchdown). So long as the necessary minimums were reported in order to begin the final approach segment, that element of the approach has been satisfied. Upon arrival at minimums, what's seen out the window is the order of the day. What's required and the altitude to which we can go depends entirely upon the procedure, the nature of the approach, in some cases the aircraft, in all cases of certificate holders, the certificate holder's approvals and authorizations, and of course, also the pilot and his or her qualification (and currency).
The point was that one does not need to have, or verify, approach weather minimums (ceiling or visibility) when approaching minimums. What's being reported isn't nearly as important as what's outside the window. One is looking outside, or half-in-half-out, depending on one's role for the approach, and at such time as one looks up and sees the required visual references (and acknowledges them, as one's SOP may dictate ("continue," "landing, etc), one isn't asking at that moment in time if the current, up-to-the-second weather is still reporting above minimums, because one is inside the FAF/GSIA and looking for visual references. Those references may be the runway, or simply pre-runway references that allow one to descend a little lower, until one acquires the runway (or must go around).
That was the point. The question regarded whether one must have legal reported weather minimums, when arriving at minimums, and the answer is that one has what one sees out the window, at that point. It was noted by some that one should have the charted (or approved; eg, OpSpec, etc) minimums, but this is not correct. Those were needed to begin the approach; arrival at MDA on a constant descent approach, or DH/DA, one isn't going to (and shouldn't) check weather to see if there are changes; one is looking for the necessary visual references (Except cat III procedures when one may not see the runway before touchdown). So long as the necessary minimums were reported in order to begin the final approach segment, that element of the approach has been satisfied. Upon arrival at minimums, what's seen out the window is the order of the day. What's required and the altitude to which we can go depends entirely upon the procedure, the nature of the approach, in some cases the aircraft, in all cases of certificate holders, the certificate holder's approvals and authorizations, and of course, also the pilot and his or her qualification (and currency).
05-10-2024, 11:02 AM
#17
Gets Weekends Off
Joined APC: Jul 2005
Posts: 251
Originally Posted by cencal83406
Cat II & Cat III require the weather to remain at or above minimums throughout the approach. However, that’s not the flight crew’s job to determine. If ATC happens to provide an update to RVR while they’re inside the PFAF and that update is below the charted minima a missed approach is required.
Originally Posted by cougar
On the Final Approach Segment (FAS), if the weather report indicates below-minimum conditions, the approach may continue to DA/DH or MDA. Upon reaching DA/DH or at MDA, and at any time before the missed approach point, the pilot may continue the approach below DA/DH or MDA if the following requirements are met.
Some countries have specific caveats to this. For example, in the UK, the approach may be flown regardless of the WX/RVR but may not descend below a 1000' AFE if the weather is below minimums. Conversely, the approach may continue if below 1000' and the weather degrades below the applicable minimum.
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