That’s perfectly reasonable on a normal approach with a decent cloudbase but in fog and poor visibility I would advise against it. If you are on an ILS in crap RVR you will be at an airport with more than enough runway to land safely even without flap. The changes in trim and pitch attitude plus the ballooning effect associated with landing flap make your life unnecessarily more difficult in an already challenging situation.
125m is the min RVR for takeoff for an operator with LVO training, though that is in EU OPS rather than any of the non-commercial sections. As far as I am aware, 400m is the min RVR for takeoff without any LVO approvals but I would have to go hunting through the documents to prove it to you.
I would certainly not choose to accept a seat on an SEP departing in any RVR at those figures though!
Now, that depends on the autopilot. Both the GFC700 and DFC90/100 are perfectly fine with full flaps.
But since I have the 4-blade prop is see no necessity to go slower than 95 or even 100 on an IAP. So I stay with flaps 50 until VMC, pull the power, flaps 100… land with 73-77 … The braking effect of that prop reminds me of a thrust reverser …
I agree, it is a bad idea to change the configuration until visual.
I also agree, departure in poor viz is little different to a night departure or flying over a low undercast. If the engine quits, it is all the same, down to luck and very little skill. It boils down to either accepting a very small risk or dont do it, and I am guessing the risk of flying a cross country of any length at night carries a greater risk.
Accepting an approach to low minima is inherently the most risky based on the number of accidents because there are all sorts of possibilities of loss of control or impacting the surrounding terrain.
I recall reading approaches to minima at night are the hardest thing we do in flying.
The key to an approach in marginal visibility/cloud conditions is that it must be stabilised. No speed or configuration changes below a predefined altitude, and maintain that speed and configuration until the flare. At the ATO where I completed my IR-ME it is 1000 feet in IMC and 500 feet in VMC. If not stabilised by then, go around.
On the DA40 the Vfe for landing flaps is so low that I use approach flaps and 90 KIAS until visual at 500 feet or I land with approach flaps. If the ceiling and visibility is craps I shall be at 80 KIAS by 500 feet.
On an instrument runway the LDA should be more than enough in such planes that you do not need full flaps.
One good reason to a avoid changing flap setting down low is the possibility of an asymmetric deployment.( but that probably never happens on a Cirrus 
)
Edit: replaced clue by key…
One good reason to a avoid changing flap setting down low is the possibility of an asymmetric deployment.( but that probably never happens on a Cirrus
What is that supposed to mean?
What does happen, both to the Cirrus and to DA40s is that pilots land in the wrong configuration. It’s a matter of flying style WHEN you set full flaps, but any experienced instructor (like me :-)) can tell you that a normal landing is always one with full flaps. Today full flaps are even taught in crosswind and bumby conditions, because it’s still the safest and best way to land. All the big schools teach it like that, the “50 flaps in gusty conditions” is, more or less, a thing of the best.
When was the last time you saw an airliner land without full flaps?
(running for shelter;-)), because I know what’s coming now.
Doesnt it mean the flap deploying full on one side but not deploying full on the other – am I missing something – not that it is very likely?
When was the last time you saw an airliner land without full flaps?
All the time. Most transport category aircraft have several certified landing flap settings; crosswind and runway length are the main factors for choosing which to use.
The difference is the final approach speed is 120-150kts which is an easy speed to fly an instrument approach in the approach will also be fully stabilised 1000’aal with no configuration or speed changes whatsoever.
but any experienced instructor (like me :-)) can tell you that a normal landing is always one with full flaps.
An SEP is certified to land with flaps in any position, and performance charts are available to determine landing distance. I think insisting on destabilising an approach below 200ft in minimum RVR is a very daft idea indeed. Surely good airmanship is adapting one’s technique to suit the circumstances?
No, the standard landing in any airliner is full flaps. And that’s the way it is taught at every airline I know of. Of course every airplane CAN land with partial flaps, and it might be necessary in very special cases, but setting full flaps for landing really has nothing to do with “destabilizing” the approach.
Correction: Re-checked and realized that some airliners do have more than one final flap settimhg for landing, like the 737’s 30 or 40 degrees. Still, I would recommend full flap landing for every landing.
Of course a partial flap landing is a non-event in most light planes. But many SR22 s have been damaged by tail strike when no flap landings were practiced!
Correction: Re-checked and realized that some airliners do have more than one final flap settimhg for landing, like the 737’s 30 or 40 degrees. Still, I would recommend full flap landing for every landing.
The normal flap setting for the 737 is F30 for landing. F40 is used on short, wet and contaminated runways and in low visibility to improve the view over the nose. You do not want to be landing Flap 40 in a strong crosswind as you can help it as it makes the aircraft a pig to handle.
The A320 series have Conf 3 and Conf FULL as normal landing flap settings. I am not yet rated on the bus but know from bar chat that both are in general use on the line.
The 747 has both F25 and F30 available as normal landing flap settings. I have only flown it in a sim ride for a job so missed the finer points, but again the manufacturers saw fit to offer crews a choice of landing flap settings, each with their pluses and minuses.
In each case it is an airmanship decision which setting to use. In the case we’re discussing, I humbly submit if you wish to land full flap you fly the approach for the last few miles in that configuration but in either case, buggering about with flap selections below 200ft in poor vis is not great thinking in my view.
We have already discussed the particular difficulties associated with a landing at minimum RVR in making the transition from instrument to visual flight with limited references. Selecting final flap requires:
- activating a switch
- reducing power
- monitoring speed decrease
- controlling the balloon
- adding power to stabilise approach speed
- adjusting to a new pitch attitude with no visual horizon
At CAT I minima at min RVR you will probably not even see the threshold at minima, merely enough of the approach lights to continue. If you wait until you see the runway you will start the process between 170-130ft and suddenly find yourself over the runway catching up with the whole picture.
Yes, of course it’s possible and doesn’t require superhuman skill but why on earth are you making an already challenging approach more difficult?
PS I fly for one rather large airline and am just moving to another, so perhaps have a bit of an idea what their training departments teach…
… buggering about with flap selections below 200ft in poor vis is not great thinking in my view.
We can agree on that, and I would never do that except in VMC if necessary. In VMC I will set full flaps when the landing is assured, in IMC once below the clouds.
I was not aware of the different flaps settings for the 747, but now I would say that both of these settimgs can be considered “the full flap setting according to the situation”, they will not land with less flaps than that, right? You know that better, it seems, but I’d say a landing with less then these settings wouldn’t be safe.
I am more specialized on the little stuff ;-) More and more the philosophy changes towards full flaps landings for all conditions. For example it’s taught like this in the Cirrus transition training. As I said, many SR2xs were damaged when pilots tried no flap landings, because the AOA at touchdown would become to big and the tail would hit the rwy …
