General consensus on when to add flaps on IAP.

Pachong

Pachong

Well-Known Member
Other than on a circle to land approach....when do you guys suggest adding 10 degrees of flaps for a straight in approach? I've been training with 2 CFIs and get different suggestions....sometimes they tell me not even to bother. Is there a rule of thumb or anything? gracias...
 
If you are going to use them, I prefer to set them up about .5 from the FAF, so it is configured before the descent. In a 172, I don't use them.
 
Pachong said:
Other than on a circle to land approach....when do you guys suggest adding 10 degrees of flaps for a straight in approach? I've been training with 2 CFIs and get different suggestions....sometimes they tell me not even to bother. Is there a rule of thumb or anything? gracias...
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If you're going to use them, and that depends solely on the current conditions, then my personal preference is to drop a notch around a mile before the FAF on a non-precision approach, or on a precision approach somewhere around 1 dot below glideslope.

Most airplanes I've flown (with the exception of the BN2 and the PA20 on Floats which had two, or the T-Craft which didn't have any flaps) have had three flap settings. On straight in approaches I typically lower one notch outside the FAF, one inside the FAF and my last flap setting at landing assured. On a circling approach, I do one outside the FAF, then as required during the maneuver.

This also depends entirely on how fast you're going. If you'll be doing 200 to the marker with 2 notches of flaps, why not slow it up a bit outside or at the FAF with 2 notches of flaps so that you can hold 150 on the way down. Its maybe 7 miles from the FAF to the MAP at most, the difference between 200kts and 150kts over 7 miles is 42 seconds, you're not saving any real time by hauling that much ass down if you don't have to.

That said, I don't typically slow to less than 120 until landing is assured. No sense in taking up the time of people behind you.
 
It's airplane situation dependant. If I am fighting a headwind of say 20kts, it a 172 I won't bother. If I am winds calm in a 172, I will use 10 and have it done prior to the FAF. I like to have whatever I am doing configuration wise done by the FAF to keep my speed as consistant as possible.


I would say there is n "general consensus." Just do what works for yu or your student. But, I do know that in most 172's on a typical precision approach in light to calm winds 10 flaps and 1800rpm should make the airplane ride right down the glide slope at 90kts with very little correction.
 
How can there be a "general consensus" on a question whose answer depends on the pilot, the airplane, the conditions, and the traffic?
 
No flaps. You're already going at a snail's pace. In older 172's you need to slow to 85 to extend flaps anyway, so that means your groundspeed is what 75kt? No thanks. I'll maintain 90-100 IAS with flaps clean. Unless you're going into a really short runway, you don't have any trouble slowing to 60kt.
 
In training aircraft for the most part you should not need flaps for an approach. There are aircraft the do need at least 1 notch of flaps.

As an example in a 172R all you need is to set your throttle to ~2000RPM and you will be close to 90kts in level flight. Once you are trimmed for level flight all you need to worry about as far as a glide slope is concerned is reducing your throttle setting for a good vertical speed to follow a GS on an ILS. The trim will hold the Airspeed for the most part.

As far as an aircraft that can use 1 notch of flaps we have the DA40. The slick airframe and the sensitivity of the controls make the pilot a bit less stable on approaches. Toss T/O flaps in and you can easily keep your airspeed around 90 and now you just need to focus on flying the procedure.

Flaps are airplane and technique dependent. Really in the end it is what works best for you without ripping the flaps off the aircraft. :p
 
I would only suggest NOT to put in more than 10 degrees until you have the runway. It is extremely easy to slow a smaller airplane from 90 to 65 knots.
 
My technique is dependent on whether the straight-in is precision or non-precision.

If on a precision, I know I will arrive at the touch-down zone at 200', with at least 5000' to flare, slow down, and land. I may or may not drop 10 degrees at the outer marker, depending on aircraft performance and wind/wx conditions.

If on a non-precision, I know I might arrive over the touch-down at or above 400', and the runway may be shorter than 5000', so...

I drop the first notch or ten degrees at FAF beginning descent. Passing thru 1000' AGL, I drop the second notch, or twentyish degrees, and slow to 1.5 Vs1. If I arrive at MDA, and stil have not reached time or DME for MAP, I drop the 3rd notch or thirtyish degrees, and slow to 1.3while looking for the runway, so that when I see the runway environment, if I am on top of the runway, I can close the throttle and drop down onto the runway with no excess speed to kill.




Just kidding...;)
 
It depends on lots of things, a major one being the aircraft. As many have said it gets pretty slow in a 172 with any flaps extended. If you can stand the boredom then go for it I guess. What I do suggest is being stabilized throughout your approach, meaning getting all the needed changes done before/during glideslope intercept or the FAF. In a 172 I would remain clean until I broke out and then just dump em all.
 
Pachong said:
I've been training with 2 CFIs and get different suggestions....
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This is one great argument for flying with more than one instructor. One instructor can make you feel like something is a procedure, when really it is a technique. No wrong answer.


sometimes they tell me not even to bother.
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It's cuz you have a hell of a headwind and your instructor has to pee.
 
When you do the "time, turn, twist, throttle, talk, tires" and whatever other T you do at the FAF, I teach the use of 10 deg. flaps as part of the "throttle".
 
Some thoughts on the matter-
1. If you fly the approach faster than 90 knots your expected to use the Cat B minimums.
2. Some GA autopilots have limitations on flap usage.
3. Full flaps missed approaches in most piston powered airplanes can be a handful. If flying a twin on an approach with full flaps if an engine failure manifests itself during the missed, good luck. You'll need it.
 
One other caveat. If flying an approach in a piston powered airplane in icing conditions use flaps 0 unless the POH/AFM specifies otherwise.
 
Blackhawk said:
One other caveat. If flying an approach in a piston powered airplane in icing conditions use flaps 0 unless the POH/AFM specifies otherwise.
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And keep your speed up as much as possible.


With ice on the wings, you have no idea what your stall speed is now.
 
I fly C172s and Cherokee 180s. Personally I've always about 10 degrees or 2 notches in the cherokee. Once I'm out of the soup and I know I'm going to land. I usually do the approach at about 80 so it's not all that hard to slow down even if I break out at 500 feet or something like that
 
Blackhawk said:
One other caveat. If flying an approach in a piston powered airplane in icing conditions use flaps 0 unless the POH/AFM specifies otherwise.
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USMCmech said:
And keep your speed up as much as possible.


With ice on the wings, you have no idea what your stall speed is now.
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You'll be able to feel it when you start to get too slow. You won't know a precise numeric value, but based on how the airplane is flying at that point you'll be able to tell when you're on the ragged edge. Best bet is to keep the speed up, and if you want to use flaps only use a single notch. If you're out of the ice, a single notch of flaps might give you a helpful bit of lift to slow up a little. It all depends on the plane and on the conditions. When you're in those conditions, remember, speed is your friend, but don't go off the end of an icy 6000' runway when you came in at 150Kts instead of 90 and couldn't force it on in time. If you need to, feel it out on the way in to land, find out where the airplane feels the worse someplace other than on short short final. Also, remember that if you're a less than salty pilot that what you consider to be a "lot of ice," may or may not be. Just use common sense. In the words of a man with way more experience than myself, "talk like your balls need a wheelbarrow, fly like they haven't dropped."
 
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