Multiple approaches, approaches in icing, and a few tricks.

[bobcaygeon]

It largely depends on how the approach is designed, not so much about the aircraft itself. For example, if the FAF is closer to the runway and there is a lot of altitude to loose, you will need more than 3 degrees. On the other end, if the FAF is farther away and there is not much altitude to loose, you'll need LESS than 3 degree.

The rate of descent for a groudspeed/dive angle are published behind the CAPs.

WHy would you plan less than 3 degrees, that is what we are all trained for? Why would you not just calculate what altitude (AGL) you have to cross the FAF at to get 3 degrees, ensure that # is above the mimimun alt. and use the higher altitude?? I personally know that on approach you can't get into trouble if your a little high (I've spent a large portion of my career using speed levers, flight spoilers, landing gear, etc to correct my inattention, suduko is hard you know )

Just my thoughts

[george sugar]

Your suggestion, bobcayeon, is in fact what is being worked towards. New approaches are being charted in accordance with a 3 degree path, rather than the minimum obstruction clearance plane. There are a few older-criteria approaches still out there, e.g. NDB 24 YHZ, that are very shallow. Certainly, charted altitudes are minimum, and if the three-degree slope requires you cross the FAF higher than the charted number, there is nothing wrong with that.

I would qualify your statement about being a bit high not being a potential for trouble, though. The inherent failing of the V/S method for an SCDA approach is that the descent at the FAF is commonly commenced a bit late, and the rate of descent is not sufficiently adjusted for this or for changes in wind conditions closer to the ground, frequently leaving the aircraft high at the VDP/MDA point. There is a tremendous temptation to increase the rate of descent upon visual contact at MDA, with the aircraft being high, and this often results in an unstable approach (as defined with a sink rate greater than 1000 fpm) in the visual segment close to the ground. This can result in ground contact prior to the runway. Alternately an over-run can occur when a subsequent over-correction to the high sink rate is applied, if the runway length is limiting and landing occurs beyond the touchdown zone.

As it states in the CBAAC, one should not have to change anything upon reaching MDA if the SCDA has been flown correctly. If drastic alterations to the flight path are required, then something is obviously not right, and a missed approach is likely the safest thing.

[sdjfkosdjf]

It largely depends on how the approach is designed, not so much about the aircraft itself. For example, if the FAF is closer to the runway and there is a lot of altitude to loose, you will need more than 3 degrees. On the other end, if the FAF is farther away and there is not much altitude to loose, you'll need LESS than 3 degree.

This is the beauty of an SCDA approach. In your example above, say that the FAF crossing altitude was lower than what would permit a 3.0 FPA, you would artificially raise the FAF crossing altitude to make it a 3.0 degree FPA.

In essence, you would cross the FAF at a higher altitude (that what the charts publish), and start your 3.0 degree FPA from there, all the way down to the DA (MDA). This is safer, instead of starting a shallow FPA, with more power on.

[sdjfkosdjf]

I would qualify your statement about being a bit high not being a potential for trouble, though. The inherent failing of the V/S method for an SCDA approach is that the descent at the FAF is commonly commenced a bit late, and the rate of descent is not sufficiently adjusted for this or for changes in wind conditions closer to the ground, frequently leaving the aircraft high at the VDP/MDA point. There is a tremendous temptation to increase the rate of descent upon visual contact at MDA, with the aircraft being high, and this often results in an unstable approach (as defined with a sink rate greater than 1000 fpm) in the visual segment close to the ground. This can result in ground contact prior to the runway. Alternately an over-run can occur when a subsequent over-correction to the high sink rate is applied, if the runway length is limiting and landing occurs beyond the touchdown zone.

I would have to say that if all calculations are made correctly, and applied correctly, often you will break out of cloud on the PAPI (if available). Sometimes, you will maybe break out slightly above, or below the PAPI. In essence, you are trying to make a non-precision approach into as-close-to a precision approach as possible, but never quite.

[xsbank]

Just to clarify one important point: unless you are working for a company with ops-specs you are NOT entitled to treat an MDA as a DH. Not many companies have this.

Also, you may find that the stabilized non-precision approach works great if you have adequate vis, but if you pop out of cloud at mins. on an ersatz glide slope, you will be considerably closer to the runway than with a dive-and-drive and you will have to decide to land 'immediately' or you will be too high/long to land. In any case, a non-precision has much higher mins and along with the prohibition from decending below MDA you will have to add the 50' or so to MDA to avoid descending below it, making it even more difficult. The Europeans are all going to stabilized now but sometimes what you gain in a stabilized approach you lose with the attendant dive for the runway.

[RFN]

The real beauty of these SCDA approaches really comes at the moment of breakout. Done properly, like others have posted, the most that should be required to transition to a normal flare is very small corrections.

With the "dive and drive" when you see the runway environment, a larger power reduction, trim reset etc etc is required, whether you see the field or not. The momentum transfer from straight ahead to a descent is not instant, and can result in a bit of ballooning, an increase in airspeed, or both. In the bush, being too high crossing the threshold is 99% as dangerous as being too low.

Using a GPS (or the occasional DME) distance (corrected a bit for distance from the GPS waypoint to the threshold), combined with a RadAlt readout in more or less level terrain, can go a long way towards confirming whether or not the SCDA is progressing as it should. 3 miles at 900ft, 2 miles at 600ft and 1 mile at 300ft should work out great. The PNF can be extremely usefull here, and it's more accurate than just descending at 800ft / min because the chart says so.

One other thing that most of us know, but still bears mentioning.

There is NO night VFR in the bush. There just isn't. A black hole "visual" approach should be flown the same way as an IFR approach. Don't be turning 1 mile final at night into Ogoki Post or wherever. The visual cues that you might be sinking may not be as obvious, or not there at all. You realize that you are sinking, and you pull in that turn to final, especially if your ball isn't quite centered, and we will be offering our condolences to YOUR family.

[xsbank]

Another debriefing point is the use of stabilized approaches to a circle. Many times with the w/x near mins if you use an LNAV/VNAV approach, you will arrive too close to the runway to which you are approaching in order to have enough room for the circle, depending, of course, on your a/c category. A dive and drive may be better for the circle.

[bobcaygeon]

XS

There are so many airports in this country that shouldn't have a circling approach its pathetic. Unless there are terrain issues circling approaches should almost be non-existent. Why are we still using NDB or VOR A's when a straight in GPS approach that costs about $2 to create and 10 minutes of a computer guys time to enter into a database? The hardest thing is try to create more 5 letter waypoints that can be pronounced or even somewhat resemble a word.

Canada's approach to aircraft safety is pathetic, they spend almost nothing, tax the crap out of it, and are trying to SMS their way out of enforcement.
As a user I am willing to contribute to the creation of WAAS approaches where we fly. Throw us a bone (ie a tax break or something) and make the certification process affordable. Right now I have the choice of an L39 or a navcanada RJ to do the certification flight. It is retarded at best.

IMHO

[Liquid Charlie]

I there is only 1 reason for multiple approaches - If you pooched the profile and you need to go back for another approach - to me that's not multiple since if you pooch it again there is a larger issue at play -- so that leads me that there is only one reason for multiple approaches -- the wx is below minimums and you are trying too hard -- go to your alternate -- ironically, unless you are driving around with an MT airplane one usually only has fuel for one approach anyway -- get set up -- make the first one count and if you miss you won't get in anyway on the second one.

VRP's and constant decent rates - been there -- will work where this is distance/speed information but before GPS and no reliable wind information it was pretty hit and miss - the other issue is you come to your VRP and commence a missed approach you might not be at the actual missed approach point and therefore if not careful could execute the missed approach and not be within the protected airspace if a published turn were executed at that point.

The world has changed -- we now have gps/fms that will give us precision approach most anywhere -- and will do temperature corrections -

The only place I understand that there is no temperature correction indicated is on a WAAS enabled LPV approach since the unit is dealing with GPS altitudes above the ground --

[Vandriver]

My personal SOP for multiple approaches is this: If, on the first approach you have ground contact at or above the MDA/DH (or sometimes during the MA) but no required reference to land a second approach should be tried. This is often the case in winter when SB/BLSN can make visibility variable, even over the short distance from FAF to MAP. I believe the terminology is "localized phenomenon". This doesn't usually happen except on NP approaches, (read: NDB) where there is a fairly wide zone of inaccuracy due to the nature LF navigation and aerodrome lighting is not really great (ie no rabbits or RILS etc.). In my experience this second time is usually a MA as well, but it has from time to time worked out. If there is no ground contact, chances are your dealing with a cloud ceiling and a second attempt would almost certainly be a missed approach so you may as well save the time, fuel and hassle and head to you alternate. Naturally, there are times when you have to temper this idea with some actual thinking. Ice on the approach, night, and multiple other factors may make a second attempt unwise even if you do get ground contact on the first go. After all we are paid to think, right?