Airspeed check against groundspeed (and stabilised approaches)

Rwy20 wrote:

You touched down to the left. As an instructor once told me: “there is no acceptable reason not to touch down on the centerline; it is a matter of concentration

Must be great to be perfect.

It looked fine to me.

Neil wrote:

Must be great to be perfect.

In no way, shape or form was I implying that I always get every landing right. Using this video to demonstrate the concept of a “stabilized approach” to a student pilot (and entering “Stabilised Approach Bonanza” as the video’s title on Youtube) just incited me to such a comment. I hope you will be able to forgive me.

I gather the problem with turbine engines is that they can take a while to throttle up – I’d always assumed this, and the inertia of large aircraft, was the reason that stabilised approaches are so important for the airlines. What’s the last moment you can choose to do a go-around without touching the ground? If you’re descending at a hundred-and-thirty something knots in a 747 where the engines will take several seconds to spool up to full power, it’s going to be at a much higher altitude than if you’re approaching at 63 knots in a PA28, or 55 knots in my own aircraft.

I know that my aircraft is prone to carb icing, so I get somewhat nervous watching all those long low approaches with low power settings. I like to stay above the glide slope and slip into land. I know that at my home airport I’ll hit a lot of sink a few hundred metres below the threshold so I’m likely to have to do a bit of work at the last minute. I can choose to go around at 20 feet if I want to so I don’t see it as a problem, but if I were to reject any approach that became unstable below 500 feet, I’d have to reject every approach.

In a more complex, more slippery aircraft obviously it’s important to ensure you’re in the correct landing configuration sooner, and issues such as turning final 10 knots too fast are going to be more of a problem so it will be obvious sooner that an approach is unsalvageable.

I can see the point in trying to fly consistently and accurately, and I guess the ‘stabilised approach’ movement has this in its favour. But someone somewhere once said ‘Always fly the aircraft you’re flying’, which to me seems very wise.

Rwy20 wrote:

In no way, shape or form was I implying that I always get every landing right.

Well, I also assumed that that’s exactly why you posted your comment….

Rwy20 wrote:

Using this video to demonstrate the concept of a “stabilized approach” to a student pilot (and entering “Stabilised Approach Bonanza” as the video’s title on Youtube) just incited me to such a comment.

I dared, full shitstorm risk ahead. The wrath of ‘instructors united’ will eternally scorch my soul for that.

All I did was trying to help Medewok. I’m not an instructor, but I went through ppl school myself not long ago, watched these videos as well, and I was really grateful I had instructors who at least didn’t disagree on how approaches should be made. Thank god. So I first learned to stabilize the approach and then got into the exemptions. And coming high, diving down etc., to me, is the exemption, not the rule. It also helped me tremendously when switching from the Piper Warrior to the Bonanza.

I am not buying this “jet only” notion and you didn’t explain why just because an aircraft is slower, lighter or less complex than a “jet”, the bullet points in the skybrary list shouldn’t be applicable. Because, where do you draw the line ? Correct flight path, correct pitch/heading, airspeed, landing configuration, sink rate, power setting, all of that irrelevant just because it’s not a jet or because it’s only GA ?

This discussion is very interesting to me as a student pilot and it is quite enlightening how the opinions on the value of GS and of stabilised approaches seem to vary and differ.
Also thanks to @EuroFlyer for posting the videos.
I must say that the last sentence from @kwlf above is probably the most relevant for me right now: Always fly the aircraft you’re flying. And for me the Aquila A211 which I am learning on is a very forgiving aircraft in which a go around can be initiated whenever you want as applying full power takes a fraction of a second only. Also my home Base of EDWF has lots of wind and trees next to the runway, the combination of which often leads to gusty conditions on approach rwy 26 especially at 200-100 ft. These gusts easily blow a VLA such as ours of the centerline. However all local pilots know that it gets much smoother past the middle intersection, as the trees are only on the first third. The remaining 600 m of runway past that mark are easily long enough to land a VLA.
If one were to take 500ft as a limit we had to reject almost half of all landings. So the advice seems well founded in principle, but impractical for our aircraft and our field with lots of piston GA.

You touched down to the left. As an instructor once told me: “there is no acceptable reason not to touch down on the centerline; it is a matter of concentration”.

There are certain airports with runway centerline lights where you will regret to land and roll-out exactly on the centerline because you ruined your aircraft’s nose wheel

We all like a little “klugscheissen” (wisecracking) sometimes…. if not, this wouldn’t be a proper pilot forum ;))

To avoid confusion in this multi-lingual community…
klugscheissen —> being a wise-ass.
wisecracking —> witzeln

EuroFlyer wrote:

I am not buying this “jet only” notion and you didn’t explain why just because an aircraft is slower, lighter or less complex than a “jet”, the bullet points in the skybrary list shouldn’t be applicable. Because, where do you draw the line ? Correct flight path, correct pitch/heading, airspeed, landing configuration, sink rate, power setting, all of that irrelevant just because it’s not a jet or because it’s only GA ?

kwlf wrote:

I gather the problem with turbine engines is that they can take a while to throttle up

We need more expert advice than I can give, professionals pilots like @what_next and @Chrisparker but to me the main difference is that when you pull the power back on any propeller aircraft the windmilling disc is a huge airbrake, slowing you down dramatically. Speed control is relatively easy. With a jet there’s no such phenomenon, it can be difficult to get the speed off. I’ve never flown an airliner but there must be inertia issues too.

The delay on power application apparently gets worse the bigger the engine, but it’s not as bad as it used to be on very old designs. You get used to that though, and you can help yourself by thinking well ahead, which is what a stabilised approach is all about