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What is considered "Stabile" in part 91 ops. ? Just curious if there is a difference between "Parts 135, 121, 91 etc.."
An example of a typical "stabilized approach" in GA:
IFR - Stabilized by 1000' AGL (ILS)
IFR - Stabilized by MDA (NP)
VFR - Stabilized by 500' AGL
Stabilized criteria:
Gear down
Flaps set
Heading established (for wind correction)
Steady needles
Constant airspeed
Constant descent rate
Basically, have the landing configuration achieved with little or no corrections by establishing your heading, airspeed and descent angle prior to reaching these altitude milestones.
Any time this criteria is not met by these altitudes, you should GO-AROUND. You'll see how important this concept is to adhere to when it comes to flying low IFR.
At my company in the E-120 we consider an approach to be "stabilized" if the airplane is straight in, on approach speed, and configured for landing by 500' AGL for VFR approachs, and by 500' to approach minimums for IFR approaches. The beauty of flying part 91 is that within the FARs, you get to decide what you are comfortable with. I personally think that requiring yourself to be stabilized by 1000' in a light piston is probably overly conservative, but that's just me.
Stabilized at 1,000' in IMC isn't really that conservative for an ILS approach, especailly for a new instrument pilot.
That's how I instructed instrument students to execute an ILS approach. Remember, most OM's are about 1,400 HAT and at 1,000' AGL, you're well into the commencement of the glideslope. If you really aren't stabilized (everything being close to a constant, with minimal corrections) by this point in the soup, you had BETTER go around. Chasing needles below 1,000 AGL in IMC is DANGEROUS. The plane should be in severe hands-off trim riding the rails with fingertip corrections.
I always flew the approach at 90 and 10 flaps at the marker isnt that how its supposed to be done?
Forgive me for not elaborating. When I said that being stabilized by 1000' in a light piston was overly conservative, I was referring only to visual approaches. I apologize for not making that clarification. Otherwise, I completely agree with you with one caveat...
Understood. You may have overlooked that I indicated the altitude (1,000') with the condition (ILS in IFR) in my first post. As I stated in that post, 500' would be appropriate for a VFR approach.
I think we both define a "stabilized" approach as being configured, on approach track/glideslope, on speed, and straight-in. That is certainly the jist of it and we both agree, in terms of answering the poster's question.
I would suggest that it's probably better to fly an approach in IMC at a moderately higher speed than the slower approach speed, i.e. in a Cessna 172, for example, the airplane would be more stable and responsive to control inputs if the approach was flown at, say 90 KIAS as apposed to 65. Very true. IFR and VFR have different speed management techniques. I taught something like 90D/80B/70F for a normal landing and maybe something closer to 1.3 for a performance landing. With the ILS approaches, 90 knots was a target for the entire ride down to minimums. For the reasons you've mentioned. It's actually easier to fly a mildly faster approach.
Under the above stated definition, that isn't really "on-speed," and therefore not technically "stabilized." The higher airspeed could possibly dictate a different flap setting, depending on the airplane, so that wouldn't technically be "configured" either. I'm not sure what you mean by the above stated definition as I didn't address a specific speed in the first post. Just that the determined ref speed would need to be constant and not fluctuating all over the place. This would obviously interfere with the stability trend of the other instrument parameters. I suppose what I was implying was that one should hold a constant speed. This speed should be stablized before reaching 1,000' AGL if for an ILS approach.
My mention of flaps and gears is that gear should be down and flaps set to approach configuration for the predetermined approach speed. It was implied that the flaps would be set ACCORDING to the specified appproahc speed which in this case, should be held constant.
It wouldn't phase me at all to see a student fly across the marker at 90 kts and 10 degrees of flaps, expecting to slow to landing speed and configure for landing when visual conditions are reached. In fact, I think this is a much safer scenario than 65 kts and flaps 25 at the marker. Student? heck, you'll find me keepin it up until short final and dumping everything. But that's only when one's become comfortable and even so, it strays from standardization which is a safety mechanism designed to prevent us from complacency and cowboy flying.
I never stated that speed should be as slow as 65. If at 25 you're refering to the midpoint (10/25/40) then I would allow that. Final flaps (40) should only be extended by DH when a landing on the runway is assured. VFR or IFR in almost all light aircraft.
Baascially, prior to reaching the OM, I wanted to see a stable 90 knots, 25 degrees and a wind correction heading with GS steady needles. No chasing. Once DH is reached and the runway is in sight, final flaps come in (depending on wind conditions).
Once in this stable condition, you're manual flying should be akin to an AP doing the job. The plane should be trimmed out for hands off speed and descent rate, allowing for only minor, fingertip corrections. No yanking, banking and throttle jocking to get to the targets while below the pertainent altitude (1,000', 500', MDA, etc.). If it takes more than minor corrections to stay within a couple of dots then I tell them to GO-AROUND.
Maybe we could say that "configured" meant configured for the approach, and not necessarily the landing. They are two different things. Same difference. I understand your distinction and maybe I confused the poster. The landing part can be treated as a second part to the approach configuration.
I think we both have the same thoughts, it's just that internet postings need clarification from time to time.
Cheers.
-Goose
Define "suppose to". If you're talking 172 or PA-28, I =generally= use 90 kts but do not use flaps for an ILS - never saw the benefit.I always flew the approach at 90 and 10 flaps at the marker isnt that how its supposed to be done?
I don't know an ILS serving a runway short enough that I would be concerned about a no-flap landing in a 172 or PA-28 (although I would probably end up with at least 1 notch in that 172 - I don't like the sight picture in a 172 no-flap landing).
But let me turn the question around - how do you respond to an ATC request to keep your speed up on an ILS at a busier airport with the flaps down?
Note the "generally." If conditions warrant, you adjust. So would I.