Landing Flaps on Base or Final?

[Lou]

Peter, I think the philosophy I was taught is you are stable in a configuration in which you can initiate a Go Around. My procedure is to approach at 90 kts. If you can't make out the runway when you reach minimums it's power and go. But if you have full flaps it would be power, retract flaps and go, which is a bigger configuration change at the most perilous point of the procedure, ie in IMC at minimums. When you are in TO flaps, you make the runway, dump the LDG flaps, slow up and land. But I would be interested in hearing about different procedures.

Gord, it's tough to find DA40 experienced instructors in Canada. It's also good to remember that most young instructors are clocking hours to get to the airlines, and say a lot of "young person" things. The one who told you that the DA40 "glides more" is a case in point. You can fly a very tight circuit in our planes, and in full flaps and and a forward slip, it will drop like a rock slow and safe. In fact, it's a fun thing to do. One last comment, IFR isn't more exciting, it's more procedural, safer and gives you a much better understanding of the "system". For me it was a "oh I get it now" thing. So now if I am travelling, it's IFR, but if I am having fun, it's VFR.

[CFIDave]

Most Instrument instructors here in the US teach having the plane "fully configured" for landing just prior to the final approach fix (FAF) when conducting instrument approaches -- leading to a stabilized approach doing about 90 knots on a DA40, or about 100 knots on DA42/DA62 twins. On Diamonds this means half flaps (T/O flaps on DA40/DA62, Approach flaps on DA42). That means you don't put in full flaps until short final when you have the runway "made," which then slows the aircraft down to Vref (1.3 times Vso) as you cross the threshold. One reason for only using half flaps past the FAF is so that you're properly configured for a missed approach (or unanticipated go-around).

[Rich]

Most Instrument instructors here in the US teach having the plane "fully configured" for landing just prior to the final approach fix (FAF) when conducting instrument approaches -- leading to a stabilized approach doing about 90 knots on a DA40, or about 100 knots on DA42/DA62 twins. On Diamonds this means half flaps (T/O flaps on DA40/DA62, Approach flaps on DA42). That means you don't put in full flaps until short final when you have the runway "made," which then slows the aircraft down to Vref (1.3 times Vso) as you cross the threshold. One reason for only using half flaps past the FAF is so that you're properly configured for a missed approach (or unanticipated go-around).

The problem I have with what I see today is to make a VFR pattern-operations final approach always being flown like the final stages of an instrument approach. And not in heavy iron, mind you, these are even in 150/152/172's. Student call in turning base and I'm trying to find the plane where I figure I'd be, but no, the fish-finder shows it in the next county.

BTW, I've heard many a pilot state they like to fly patterns such that if they lost an engine they could still make the runway. On an instrument approach that's not going to happen. The typical precision approach path is typically designed to be roughly 3 degrees. The DA40's best no-wind glide angle is stated to be about 6.5 degrees. Just sayin'.

[haykinson]

BTW, I've heard many a pilot state they like to fly patterns such that if they lost an engine they could still make the runway. On an instrument approach that's not going to happen. The typical precision approach path is typically designed to be roughly 3 degrees. The DA40's best no-wind glide angle is stated to be about 6.5 degrees. Just sayin'.

But on approach you are carrying more speed (90kt) than best glide, which means you may be able to turn that extra speed into enough altitude to give you the glide to the runway.

This may be worth a test. Fly a wide pattern, set yourself up on a long final at approach speed, and chop the power to idle while on glideslope and see if you've got enough energy to make the runway at Vg.

[Rich]

There is good reason for a shallow, 3-degree approach in IMC. In VMC in a DA40 (and many other planes) there is not. Keep in mind also that very commonly on final you will have at least a bit of a headwind.

[jb642DA]

BTW, I've heard many a pilot state they like to fly patterns such that if they lost an engine they could still make the runway. On an instrument approach that's not going to happen. The typical precision approach path is typically designed to be roughly 3 degrees. The DA40's best no-wind glide angle is stated to be about 6.5 degrees. Just sayin'.

But on approach you are carrying more speed (90kt) than best glide, which means you may be able to turn that extra speed into enough altitude to give you the glide to the runway.

This may be worth a test. Fly a wide pattern, set yourself up on a long final at approach speed, and chop the power to idle while on glideslope and see if you've got enough energy to make the runway at Vg.

To test this - Start in level flight at 90 knots and pull power to idle. Time how long it takes to slow to "best glide" (for your weight) and then convert that to the distance traveled over that time.
I bet the extra 14-22 knots at the start (based on your weight) won't allow you to "stretch the glide" much at all.


From the AFM:
3.1.2 CERTAIN AIRSPEEDS IN EMERGENCIES (I had to convert chart for formatting)

Flight Mass ___________Airspeed for best glide angle (Flaps UP)
850 kg/1874 lb ______60 KIAS
1000 kg/2205 lb _____68 KIAS
1150 kg/2535 lb _____73 KIAS
1200 kg /2646 lb ____76 KIAS

[ultraturtle]

Pretty good mix of twin and single owners replying to this thread, and I think some may have forgotten the whole point of carrying a spare motor around.

If it is all about making the runway in case of engine failure:

• - If flying a single engine, 1-1=0, so there may be some merit to waiting until short final to select landing flaps.
  - If flying a twin, 2-1=1, so you can make the runway if an engine fails at any point in the flight. In case of engine failure while fully configured on final, add power and rudder on the operating engine side, select approach flaps and land.

I'm a big fan of stabilized approaches with no configuration changes on short final. Hauling a spare motor around gives me the redundancy that makes it a smart move every time.

[TimS]

This one is interesting. Admittedly, I never did IFR training in the U.S., but here in Europe I was taught to follow the concept of a stabilized approach i.e. having sinkrate, heading, and speed arrested while being fully configured for landing prior to sinking through 1.000ft AGL (in IMC) or go around. The reason being precisely to avoid configuration changes on short final.

That is a legacy of jet thinking applied to piston planes.
The vast majority of piston planes do not have sufficient power to overwhelm the high drag devices; while most jets can fly away on one engine even with full flaps deployed.

Overall, most are now advocating for a stable approach from FAF to landing assured which is normally around 200 AGL for instrument approaches. I was taught to apply the same to even visual approaches.

Tim

[dgger]

This one is interesting. Admittedly, I never did IFR training in the U.S., but here in Europe I was taught to follow the concept of a stabilized approach i.e. having sinkrate, heading, and speed arrested while being fully configured for landing prior to sinking through 1.000ft AGL (in IMC) or go around. The reason being precisely to avoid configuration changes on short final.

That is a legacy of jet thinking applied to piston planes.
The vast majority of piston planes do not have sufficient power to overwhelm the high drag devices; while most jets can fly away on one engine even with full flaps deployed.

Well, one could also suggest that this is saftey thinking applied to all planes. I do not have a reference, but IIRC that about 75% of all landing accidents start with an unstable approach. So, there is certainly something to gain here - no matter which and how many engines.

I would argue that flying IFR in a single-engine aircraft, in particularily in IMC, you already did „price in“ your personal risk of an engine failure. From there there is not much to gain from not coming in stablized.

Overall, most are now advocating for a stable approach from FAF to landing assured which is normally around 200 AGL for instrument approaches. I was taught to apply the same to even visual approaches.

The FAF is typically farther out. I do not recall seeing one lower than 1,000ft AGL. So, from there you still have a number of miles to go. The question here is how you would translate that to flying a pattern in a single engine and I can see the value of being able to glide a single to the airport while in the pattern.

[TimS]

Well, one could also suggest that this is saftey thinking applied to all planes. I do not have a reference, but IIRC that about 75% of all landing accidents start with an unstable approach. So, there is certainly something to gain here - no matter which and how many engines.

I would argue that flying IFR in a single-engine aircraft, in particularily in IMC, you already did „price in“ your personal risk of an engine failure. From there there is not much to gain from not coming in stablized.

No engine failure needed. Have you tried a full flap go around in a Cessna 172 when 200ft AGL and no runway? Even a more modern Cirrus SR20 with full flaps?
My point on the jet with a single engine is the plane has so much excess power it can handle the additional drag and meet climb gradients. Most piston planes even with all engines working and full flaps cannot.

The FAF is typically farther out. I do not recall seeing one lower than 1,000ft AGL. So, from there you still have a number of miles to go. The question here is how you would translate that to flying a pattern in a single engine and I can see the value of being able to glide a single to the airport while in the pattern.

I was taught engine to idle abeam the numbers and you should be able to land 300 ft past the numbers; works so far on any single engine plane I have flown. It may take some practice, but makes a smooth, and tight pattern. Never did work in a twin yet; but I have tried a few....

Tim