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-   -   RNAV and visual approach (https://www.pprune.org/tech-log/614636-rnav-visual-approach.html)

Vessbot 27th Oct 2018 09:02


Originally Posted by 763 jock (Post 10293646)

There is no circling minima on the RNAV 35 procedure. Unless you are able to maintain VMC (as above), the only option is to fly one of the other approaches to its associated circling minima.

Simples.

This isn't the OP's scenario, but for the sake of argument let's say the ceiling was something high like 2500 and you're 1000 below it maintaining required cloud clearance, what's wrong with getting cleared for a visual approach and executing it, regardless of what you were cleared for before? How is that different from the routine multitude of times we are cleared for an IFR procedure and then (partway through it) cleared for a different one?

Edit: come to think of it, this is not a counting the number of angels that can dance on the head of a pin exercise, I've done exactly this in the past. (USA).

sabenaboy 27th Oct 2018 09:03

Dear Lantirn,

I'm very familiar with CFU airport and I share your feelings. I go there regularly. It's indeed ridiculous that ATC would not allow you to do a visual after breaking clouds on the RNAV35.
Anybody familiar with the airport will know that there are no close in obstacles on downwind or base leg for RWY17. You're flying over the water! So as long as you're VMC below the clouds and have the terrain in sight north and west of the airport, flying the visual approach as you intended is a perfectly safe and sensible thing to do!

763 jock 27th Oct 2018 09:18

Also very familiar with CFU. Been flying there every Summer for the last 25 years.

I'm not an ATC expert. But the chart says "not authorised" for the RNAV circling. So I would imagine ATC can only offer the RNAV approach when 35 is in use. What you choose to do on the day is up to you. Just don't screw it up if you are bending or flexing the rules.

I've seen at least two careers come to an abrupt end when things went wrong operating outside the rules on "visuals". One involved actual damage, the other very nearly ended up in the water at CFU.


sabenaboy 27th Oct 2018 10:24


Originally Posted by Lantirn in post #10
Of course 6.5.3.2 is a good reason for ATC do deny any visual approach. But i have flown many visual approaches there.

6.5.3.2 is only about the case where ATC initiates the visual approach, not when it's the pilot asking for one.
(A Squared already gave that reply in post#20)


Originally Posted by FlyingStone in post #22
Night visual turned into CFIT. Read here.

That proves that it's not a good idea to let a civil judge with zero aviation expertise make the judgement in such a case. It's absolutely ridiculous that an ATCO gets blamed for a stupid pilot flying into terrain after requesting and getting a visual approach!

Originally Posted by hkgfooey
Why not simply ask for radar vectors for downwind 17 which will bring you to the MVA of 2900 ft or fly the LCTR A approach with a CAT C/D circling minma of 1700 ft and then left base for 17. I would see that as better than the RNAV 35 anyway as you join a left downwind with the runway in sight out to the left all times.

Because CFU airport often has a thin stratus cloud layer at around 1600' but with great visibilty as soon as you get under it. The OP wouldn't be asking the question if he could see the runway at 2900 ft. :ugh:

TOGA Tap 7th Nov 2018 07:14

During the circle to land part on an instrument approach pilot must :

1) see the landing runway at at all times during the circle and
2) stay within the prescribed distance radius as per aircraft category.
3) maintain prescribed MDA
4) keep speed bellow max for aircraft category

The combination of MDA, distances and speed during level part of a circling app protects you from all obstacles and terrain.
You are not obliged to see them - you just look for the landing runway - just as you do in a straight in approach.

It is an instrument approach as any other.

Visual approach s quite different - you must see the surrounding terrain and obstacles all the time and be able to safely avoid or overfly them. Speeds and altitudes are up to you.

So the determining factor is the ability to see enough of terrain and obstacles.

Now the question is: can you follow a straight-in segment of a published instrument approach until breaking out of clouds and then require visual approach instead of continuing with circle to land as published?

It is possible providing the pilot can see the terrain and obstacles.

ATC person is not aware how familiar ( or non-familiar ) is the pilot with the surrounding terrain nor what pilot actually sees from the aircraft.

By night with some rain showers acting as curtains terrain and obstacles are simply not visible.

Also Calgari accident shows that the ATC can be found to be partly responsible in case of an accident - depending on what the particular judge thinks about it.

I am not expert for procedure design but I suppose that something in the particular RNAV approach makes circle to land impossible.

So in this situation where there is no published circle to land, wx not ideal, night, foreign crew etc... ATC should be very reluctant to issue a visual approach clearance.

And pilots should not press them for one.

Day time may be different.


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