5.3 degrees is not trivial in the TB20 either. You need gear down and full flap at the FAF, and the speed about right i.e. 80-90kt. I have done it. The KFC225 will fly it too, with full flap and gear down.
I wonder what the steepest is that an SR22 can fly?
Speaking of avionics, I can’t face having to choose somebody to install it. There is really a very poor choice. And it would be a 30k+ job, to do it properly (not a bodged-in GNS430W).
It is not good practice to drop full flap in a twin when you cannot commit to land (for example because you are in IMC or haven’t yet got a landing clearance.)
You do it, of course, to get in, but it is a risk.
Thing is, manufacturers usually don’t publish Vbg for flaps and gear down, as it seems nonsensical to do that. But for the above mentioned exercise, one would need this number in order to find out which speed to stay away from in order to minimize the glide, i.e. to manage to keep on a steep glideslope. The trick is to either go very slow (something like 1.3x Vs, but that might upset the controller) or fly at Vfe. In between is probably too close to Vbg.
If unable, a dive and drive would probably be the best thing in terms of procedure minima.
The other issue is keeping enough power on the engine(s) not to cool it/them too quickly. That also means keeping the cowl flap(s) retracted so being unable to use their drag.
I flew this approach last summer – final approach loses 6000 ft on a 5,4 degrees slope. Keeping the engine happy was indeed the problem, even with full flaps and speed brakes (Cessna 400 Corvalis). In the end I stopped following the glide when I broke out under cloud around 3500 ft, then I added a little power and made a circling approach, thus managing to keep CHT’s in the green. The Twin Otter coming in next did not seem to have a problem with the descent angle, it is really made for this kind of flying.
Anders wrote:
Are our aircraft “certified”?
There is the question about how to establish minimum RVR/VIS. Of course, it is allowed to use Jeppesen or similar products (GM1 NCO.OP.110), but the prescribed method for establishing minimums only works for final glide angles up to 4,5 degrees (CAT A & B aircraft):
GM3 NCO.OP.110:
(a) In order to qualify for the lowest allowable values of RVR/CMV specified in Table 3.A, the
instrument approach should meet at least the following facility requirements and associated
conditions:
(1) Instrument approaches with designated vertical profile up to and including 4.5° for
Category A and B aeroplanes, or 3.77° for Category C and D aeroplanes, where the
facilities are:
(i) instrument landing system (ILS)/microwave landing system (MLS)/GBAS landing
system (GLS)/precision approach radar (PAR); or
(ii) approach procedure with vertical guidance (APV); and
where the final approach track is offset by not more than 15° for Category A and B
aeroplanes or by not more than 5° for Category C and D aeroplanes.
(2) Instrument approach operations flown using the CDFA technique with a nominal vertical
profile, up to and including 4.5° for Category A and B aeroplanes, or 3.77° for Category C…
Although it seems the restriction is void when flying non-CDFA NPA’s, aka dive-and-drive? I am not sure I can make sense of that.
These are obviously much easier with turboprops or aircraft with speedbrakes. Jets and turboprops will usually find it easier than piston aircraft. With the power there is less of a concern with hanging out the laundry ie if you need to drop gear and landing flaps and go to idle and you should be OK. Most however will have speedbrakes.
But these sort of aircraft need an annex added to the POH for steep approaches.
The Mustang has a supplement for 4.5 to 5.5 degree approaches which has different reference speeds and normal procedures including speed brakes extended until landing.
I fly each of the London City ILS approximately a dozen times every 6 months, in a PA31. It isn’t too tricky but you must plan ahead and most of the salient points have already been covered. Interestingly, we operate the same PA31 out of Shoreham and the 5 deg approach is much more challenging here as you have to contend with a far more narrow and short runway.
flew this approach last summer – final approach loses 6000 ft on a 5,4 degrees slope. Keeping the engine happy was indeed the problem, even with full flaps and speed brakes (Cessna 400 Corvalis). In the end I stopped following the glide when I broke out under cloud around 3500 ft, then I added a little power and made a circling approach, thus managing to keep CHT’s in the green.
Why would you try to keep the CHTs in the green during final approach?
boscomantico wrote:
Why would you try to keep the CHTs in the green during final approach?
Exactly, shock cooling is hardly an issue once you have been at a low power setting.
