Thursday, January 30, 2014

Approach Flaps

Since I'm not flying as much due to the wx I find myself reading more on the forums. I found this topic of when to add flaps on an instrument approach in one of the cloud buster sections.
If shooting an approach what are your thoughts on when to put in approach flaps? Do you configure at the Initial Approach Fix (IAF), Final Approach Fix (FAF) or when you break out?  Some pilots seem to add flaps prior to the FAF so as not to disturb the aircraft configuration and continue on a stabilized descent.  Others, like myself, configure for 90 knots as we approach the FAF in order to time the approach based on the approach charts FAF to Missed Approach Point (MAP) information.
For the instrument student approaches are pretty intense to begin with, especially when coupled back to back to back. Despite us all thinking that our instructors just lived to torture us there was a reason the CFII’s like to pile it on. The overload teaches us to juggle more balls at once and once you can keep all the balls in the air safely it actually seems to slow everything down around you. When you can really juggle all the balls you find yourself looking for things do.  I was taught to set it and forget it at the IAF, configure for 90 knots and approach flaps, fly the approach.  However, in the real world we are often asked for best speed and that opens a different can of tennis balls.
Once I had the instrument rating in hand I flew with different pilots that possessed different ratings and levels of experience. Most of the folks seem to configure gear and flaps at the FAF.  In my Sundowner it’s not a monumental task to slow down so I find it best for me, just prior to the FAF, to configure for speed and fly the approach until I break out. I do this for two reasons; First, if I have to go missed I am clean and climbing with no tendency to power up and get nose high for a potential departure stall. Second, trudging along at 90 knots seems like forever so I like to keep the speed up and only make a configuration change once the landing is assured.

As they say, your mileage may vary. What do you do when flying the approach?


Geoff Nelson said...

I think it may vary by plane on it's effectiveness or not. For me, having one notch of flaps out really stabilizes my plane. Not that it's wild before that, but it makes a noticeable and beneficial change. Depending on my approach I'll drop the gear and the first notch of flaps at the FAF, but more likely just before. I'll leave it in that configuration till landing is assured. On the rare occasion my approach will end up close to minimums on a precision approach, I might put out the second notch out to start slowing from approach speeds towards my landing speed a little before the DH.

Gary said...

Geoff, thanks for posting. If I wasn't breaking out and I need to slow down a bit more approaching DH I would add a notch of flaps to the Sundowner too.

D.B. said...

I agree it would vary by aircraft - A 747 and a 172 are very different animals. But for most light aircraft (Sundowner and Bonanza) I fly the approach at 90 to 100kts, which is a bit fast for flaps. I would only lower them before breaking out if I was descending on a precision approach to a very low DH for a short runway, most of which don't have instrument approaches anyway. The ones with approaches are usually 4000/5000 ft or more. Besides which, it's easy enough to land on a longish runway without flaps if I was unable to reconfigure at 200 or 300 ft. Why bother with them before that? I'm in the keep it simple camp for the approach - make as few changes in IMC as you can.

D.B. said...

With my CFII hat on now, I think it is entirely up to you. I've never heard or read of any guidance from the FAA - only that while not mandatory, flying in a manner other than as listed in the POH can be seen as evidence of recklessness. What does the C23 POH say? Nothing, right?

Chris said...

Gary -

This is a timely post as I have been pondering this very issue lately. When I was training and still new enough at it for approaches to by a little overwhelming, my instructor suggested we slow things down a bit and I started configuring the airplane at the FAF similarly to what I would use in the pattern just prior to turning to base (flaps 10, 75 KIAS). This was a familiar pattern configuration and felt nice and stable. The examiner thought my technique was good and ATC hasn't complained, but as I've been reading on the subject recently, this is clearly slower than most pilots fly their approaches. I had recently resolved to fly them at 90 KIAS to better align with the times given on the plate for LOC approaches and help ATC with spacing.

90 KIAS is within flap operating range for me (Vfe is 103) and I was debating whether flaps at this speed made sense or not. It seems to me that, without flaps, the airplane is in great shape to go missed. On the other hand, flaps 10 at the FAF would minimize the amount of reconfiguration necessary for landing. I think I need to try it both ways and see what I think.

Gary said...

Chris, That's the best way to figure it out, go out and see what works for you. I'm sure you have the settings figured out for the level, climb and descent, now just fine tune.

I guess I got in this habit of no flaps until landing assured returning to KILG and dealing with ATC and charter jets, now an airline too.