We have now gone from, question, steep approaches, do you do them, through every argument for and against, too, Air Transat Airbuses, floating in, having run out of fuel, for 120km. Quite breathtaking. I would challenge that, if you were to ask your average PPL club renter, what the best glide speed, for their chosen club mount for the weekend, how many could tell you? I would venture, not that many. I will highlight that no offence is meant by that, I just think it to be accurate.
So, why not, as you are setting up for whatever airfield you are going to, be it VFR, or IFR, plan to execute the best possible combination for the weather conditions, the wind factor, the characteristics of the plane, and the topography of the approach phase. Because when I fly, never do all of the above remain consistent.
Nobody will suggest a power idle approach at minimum speed,
Well, like almost everything in aviation, it depends on what you want to achieve. a proper STOL approach incorporates just that.
a proper STOL approach incorporates just that.
Wouldn’t that better use a rather nose high attitude with substantial power and then in the right moment remove the power?
I disagree. In a really tight spot, this is the best way to get the plane down and stopped in the space available. This technique requires skill, and if the engine falters along the final approach path, you are going to damage the plane, a glide landing will not be possible, but you’ve already made that choice, in choosing to land there in the first place.
It’s fun to hear the guys discussing things before you land. They didn’t think you actually would land because they thought you couldn’t take off again 
It’s fun to hear the guys discussing things before you land Quote
I had no idea what they were saying, other than they were very courteous when I got out. I had no concern about getting airborne out of there, as I knew exactly where my takeoff roll would begin. It’s landing into a tight runway which has the uncertainty. I had done the math, the available runway length was 15 meters longer than I needed for landing.
Wouldn’t that better use a rather nose high attitude with substantial power and then in the right moment remove the power?
I thought so aswell for long time, but the power idle approach has the advantage that it allows for much steeper approaches and a much better visibility on your landing area. But it is not that easy to fly (since the flare has to be timed more precise) and especially in gusty winds you have to be careful.
The manual says for our fully loaded 172b that the landing figures are achieved with power idle, full flaps, 63 mph approach speed and V_S0 = 51 mph, what is roughly a factor of 1.2. According to the manual the landing distance should be 1150 ft in zero wind at MTOM. The values for a light loaded C172b are 53 mph approach speed and 870 ft. I tested it yesterday in roughly 12 mph headwind (reducing these figures to 920 ft or 700 ft respectively) and found that if you are comfortable with the reduced flare timing margin, these figures have proven to be very accurate.
However, video debriefing (something I like to do when testing flight techniques) showed still an existential flare. The idea of steep and slow (as slow as 1.05 VS0 in clean air) is to minimise the flare and thus reducing landing distance even further. This means that you might have to aid the flare with a shot of gas to break the descend. Doesn’t work with all aircraft, though. The DR 250 will break rather violently, for example.
The advantages over a high nose high power approach are better visibility, more power reserves for a go around and less necessary rudder input (and with that less susceptibility to enter a spin). On the other hand you have a bigger pitch up moment on a go around and a narrower timing for the flare. Since at the very slow idle approaches you may have to use power for the flare, you have to rely on the engine, too, so that is not an argument.
The Morane manual describes the high pitch high power approach with a Va = 110 kph and a corresponding V_S0 of 95 kph (factor 1.15). At some point I have to try the steep idle approach with the Morane, I suspect it is considerably shorter.
Of course, this is just a discussion about extreme STOL procedures and to go to the performance limits of the aircraft, not for everyday use. I usually prefer stabilized approaches with something between 3° and 5° glide slope, depending on the aircraft. It is much more relaxing for pax and flight instructor :-)
Nobody will suggest a power idle approach at minimum speed, that is why I used the term “best glide speed” for gliding approaches, meaning at about 60 to 90 knots for most GA aircraft. I suppose all of you will know your speeds for emergency landings ??? So no discussions about effectiveness of controls at these speeds anymore. How would you do an emergency landing if you had to but never practised that sufficiently before ?
Why would you make an emergency practice the standard approach? “My” aircraft glides at 81 knots, which adds ~ 15 kts of extra energy compared to a powered approach, meaning that there will be a loooong float.
QuoteIn my country during PPL training it was normal to do many landings with power idle from 2000 feet above the airfield, dead easy with the correct strategy and absolutely predictable, flaps only as required in the last moment when you actually need them for hitting the spot on the runway. So when a student is capable to do that any day – and we did ALL landings with idle , where is the problem for the experienced professionals here ?
The problem is that professionals usually don’t practice emergencies with passengers on board…
A powered flat approach with a lot of flaps and noise over populated aera is simply a disgrace for the proper pilot in my eyes when there is no need for that other than training for PAPI use. In these days Rotax have a thing with leaking carb floats – as Lyco et al had with US carbs for a while/still ? So in this respect I would not be so keen to do lots of dragging approaches over unsuitable terrain : The engine would be OK at higher power settings but would stop at low power with sinking float and far too rich mixture. This would be no problem if you do a gliding approach as you would make it to the airfield anyway. With a flat approach you will end up in the woods with minimal altitude for no time at all to react in a useful way. .
You’re saying that your engine is so unreliable you need to do a glide approach all the time? Fair enough!
There is some logic in maintaining 1000 or 2000 feet around the airfield or cross country so as to have some option to deal with emergencies. You are giving that up with useless flat long approaches over unsuitable terrain , demonstrating that you obviously are not in a training state for appropriate landing techniques . In 2001 an Air-Transat Airbus did an engine out gliding approach for 20 minutes and 120 km to the Azores for a perfect landing, minimal hydraulics available of course. So when they could do that …… Vic
Trying to figure out what point you are trying to make. Absolutely agree that some height during a cross-country gives more margin and more time to deal with emergencies. But even you don’t remain within glide distance of an airfield all the time do you? Neither do all Airbuses make glide approaches into their destinations since the Azores example. Perhaps I’ve misread the point you’re trying to make.
We have now gone from, question, steep approaches, do you do them, through every argument for and against,
Don’t you love those discussions :-) I think the reason is that some people are advocating to make it standard practice. I think everyone agrees that it’s a good idea to sometimes deliberately and intentionally practice a glide approach.
I still see no real benefit of a dragging powered approach for a “normal” landing when I don´t have to do it this way. Surely everybody will be able to produce a reasonable touchdown this way but this demonstrates just a poor state of training. It simply produces a lot of avoidable noise to inhabitants in the approach sector and at the same time an extra risk of getting hit by an aircraft as the pilot ran out of options in the minimal altitude for a few extra miles in case of engine trouble or any other problem.
Are you absolutely confident your engine will never ever stop in the air ? There is possibly at least one poster here with more than one dead engine experience , not in the approach, I believe. But thinking of float troubles with Schebler or Precision carbs over decades, plus Rotaxes right now, how can you be sure ? In that case you will only know when reducing power, no matter how the preflight mag check went, the problem can develop in flight unnoticed.
Maintaining 2000 ft altitude cross country is obviously not a purpose to glide to the next airfield but instead to have a few more seconds to think and find a field in gliding distance (best glide speed) for an emergency landing. So to get the feel and the view in this mode of operation we did ALL approaches with power idle, or close to – no extra cost, no extra risk, just the opposite. So why on earth should I do the “Airliner” all the time for no purpose ?
Would you care to tell your aircraft ? Is your quoted speed best glide speed for max distance per height? And that at engine idle ? Windmilling should do a lot for decelerating so I would not believe that long float, depending on prop design. In a gliding approach the trick is to set FULL flaps only very late when you know you will make it. Your aiming spot will be quite a bit before the strip with reduced speed at that position to begin the flare so at the perfect spot you will be about right for the touch down. No need to account for obstacles in the flight path as you are going in a bit steep. So even with an initial glide speed of 80 kts in the round out the speed will come down nicely, it´s just a matter of practising – and that is the real issue here.
By the way, there are discussions about continuous “gliding” approaches for airliners to fight noise issues. As it is presently, ATC likes to see altitude reductions in several steps with long distances of noisy dragging flat approaches for a final landing. In a time of sophisticated on board avionics this is stone age strategy for me.
I guess all parachutist aircraft pilots do the idle gliding approach for standard approach, for a good reason obviously, same goes for glider tugs.
“Dragging it in” and a normal approach with the power on are two things. As i said before: only an approach with (some) power on will give you maximum control of the airplane, especially in windy/gusty conditions.
No, glider tug pilots etc don’t do stabilized approaches, but that’s a completely different matter.
As I often do, I practiced a number of steep, power off approaches in the last few days. My home runway has no safe undershoot area, so I aim a bit down from the button. With full flap out (40 in my 150) I was still a little hot and high; no problem, a full slip, which I continued to ground contact, and made my spot within a few feet.
only an approach with (some) power on will give you maximum control of the airplane, especially in windy/gusty conditions.Quote
I don’t agree. It is airflow over the wings and flight controls which affords better control. Airflow is a product of airspeed, not engine speed. Yes, the power will affect elevator and rudder, but it is rare to be short of elevator control (when was the last time you recall hitting an elevator control stop?), and who uses the rudder enough, let alone to full? It’s the ailerons effect which plays a large role in the sense of control in the final stages of landing, and the engine does zero to affect aileron effectiveness, other than enabling more speed.
The affect of power which appears to give you more control is that it allows you to stretch out the flare, and thus have more time to get the control in the way you’d like it. If I fly a glide approach to the water, I’ll fly it faster (as “runway” length is usually less an issue). I will be within a foot or so of the water, holding it off through the slowing form the extra speed, and my flare and touchdown will be identical to a power on approach, as I’m simply bleeding off speed from a little excess, rather than from closing the throttle – the plane flies the same.
Bear in mind that certification requires that compliance with all the control and handling requirements is demonstrated power off. The planes will do it, its the pilots who may dislike the very quick flare and touch which results from a glide landing.
The two best reasons for a flat dragged in approach are to prevent overcooling an engine with a power off approach during very cold winter flying (in such cases, I’ll keep the power up, and slip down, to keep the engine warm), and very STOL “chop and drop” spot landings. Otherwise, I like a more high and steep, less power approach. With a happy engine, you can cheat a bit of power in as the flare begins, if you like – but try not to depend upon it!
