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PFL advice

Old 30th Nov 2019, 17:38
  #41 (permalink)  
 
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Originally Posted by double_barrel View Post
I think I was well taught how and when to attempt a restart, although of course they always fail to restart during training! I'm not sure how that could be safely practiced except in a simulator ?
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If the student does not complete the engine failure cause check as part of the practice forced approach I terminate the exercise and start over.

i sometimes restore partial power as soon as the cause check is completed.
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Old 1st Dec 2019, 12:59
  #42 (permalink)  
 
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When I was instructing I used these diagrams to help with PFL briefing. The answer to the question 'is it OK to reduce flap setting if the approach gradient is now becoming too steep' was: 'yes, but bear in mind momentary loss of lift and reduced stall margin'. It's a judgement call, depending amongst other factors, on remaining distance to landing. In other words, is there sufficient height/range to absorb the momentary loss of lift. On the subject of partial failure: if the failure is only partial, it might be possible for the pilot to reach the nearest airfield, using whatever power is available from the engine and flying the aircraft at its minimum gradient gliding IAS to achieve the shallowest possible descent path. However, it should be borne in mind that a partial failure might develop into a total failure. It would be unwise, then, to attempt to reach an airfield if flight over terrain unsuitable for a forced landing were involved. In this case, the safest course of action would be to close the throttle and initiate the forced landing procedure as for total failure, remembering that the residual power available from the engine can be used should it be needed to reduce rate of height loss. The pilot should not rely on this residual power, however, since it will not be available if the failure becomes total.




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Old 1st Dec 2019, 14:48
  #43 (permalink)  
 
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Here's the full PFL briefing. Forgive the absence of feminine pronouns - the briefing was originally compiled in the days when 'he' implied 'he or she', 'his' implied 'his or her' &c.

Engine failure procedure
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Old 1st Dec 2019, 23:55
  #44 (permalink)  
 
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Originally Posted by double_barrel View Post
Interesting, obviously a terminology difference here. I thought PFL meant an actual landing on a runway as opposed to a practice approach out in the countryside but with an overshoot. I have done dozens of the latter and they usually go OK, the problem is that you never really know how it would have turned-out!
In NZ we have specified locations called Low Flying Zones where you are allowed to legally fly below 500' AGL but only as part of dual instruction training flight and with a qualified instructor who is familiar with the zone. I got to do some practice forced approaches down to 5 feet AGL before overshooting. It certainly answered the 'would we have made it?' questions.

Although I've never had to do one for real, I'd prefer landing in the right spot a little too fast over undershooting and hitting something.
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Old 2nd Dec 2019, 00:09
  #45 (permalink)  
 
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I never go below 500 ft on this exercise. If your instructor canít tell within 100 ft where you would touch down when you are at 500ft AGL, you need a new instructor
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Old 2nd Dec 2019, 02:46
  #46 (permalink)  
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I think that despite my great respect for Big Pistons, we're going to disagree on this. I also accept that BPF is probably thinking initial training, where I am talking advanced training, but... For me, the PLF is an exercise in handling the plane to a touchdown. I view the cause check as more an enroute training element. At some point, you're committed to a power off landing. It is at that point, the training to which I refer begins. I train practice forced landings to a touchdown. Of course, I set things up, so there's lots of room, and after the first "surprise", others will be repeated to the same spot. I find it allows the candidate to rejig their perception, and improve by iteration. I agree that the drill can be begun at altitude, and the cause check, and setting up the glide be the first element of the exercise, but sometimes a landing will be the result. However, in all cases I train this, it is to an already experienced pilot, as a part of type training. Aside from knowing the location and function of the secondary controls, the exercise is to accurately manage a rather different handling (usually drag) airplane to a successful touchdown.

I recall in particular, training a class one instructor to fly skis in a PA-18. This pilot, though very competent in a 172 on wheels, was really out of his element in the PA-18, and a revised idea of what would be a suitable landing site. Of course, I set him up with ample room, on a snowy lake I knew well, with many features of the surface and shore with which to judge. Lining everything up for his ease in the exercise, he mis judged so badly that he would have had to be touching down during base leg to make it work out - so we went around. I demonstrated from the same position, stated my touchdown point from crossing overhead at 800 feet, and landed where I said I would. From the front I heard: "Can I try that?". I told him that not only could he try it, he was not going solo until he could repeat it. After an hour, he could. Similarly, training a 200 hour pilot in a 182 amphibian, which glides rather steeply. I really did want to send him solo, but I needed to know that if it quit, he could get it down safely - and he knew he had the confidence to do it.

I find that too many pilots rely on the use of power to modulate the final stage of approach and flare. The difference in how quickly a plane will slow to stalling speed, when power is not available is important to know. If I thought that all pilots were being trained power off landings from mid final, I'd be content. But too many are carrying power into a protracted flare, and I just do not know that they can manage to get the plane safely on, with much less time available to refine the landing from ten feet up. So, for me, it's power off from a close mid downwind, tell me your selected touchdown point, and then do it.

A background aspect of my assertion of the importance of actually touching down out of the exercise, is the fact that though I am a licensed helicopter pilot, with experience on a number of types, I have never flown a "full on" autorotation from altitude - apparently insurance does not allow it in training. I've pulled into the flare in the auto many times, but only ever power recovered (which I think is even more challenging - changing horses mid stream!). Instructors assure me that I would have made it, but I do not have the confidence from having done it myself. I don't want a real emergency to be the first time!

For some of my less aviation familiar passengers, on a nice day, I'll often very slowly and gently pull the power to idle, and gently glide all the way to touchdown. On the ground (or in final, depending upon the person) I'll say "by the way, if the engine had stopped, this is exactly what it would be like" (if there's disbelief, I'll make a show of turning the mags off for a moment). People seem to appreciate understanding that a power off landing is not the end of the world - so pilots should understand this too.
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Old 2nd Dec 2019, 12:27
  #47 (permalink)  
 
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On the whole retracting flaps and experiencing an altitude loss.... isn't that mostly a butt feeling? Cause if managing the possible increased speed correctly, and being able to maintain the best glide throughout the retraction, there shouldn't be any loss of altitude?

On the other hand, in case of a headwind, it may be feasible to keep your speed a bit higher than best glide in order to reach a desired landing site, otherwise the better glide may be eaten up by the reduced speed over the ground.

Another one, which I've heard, but never tried though.... increased speed into the ground effect, and then using the ground effect to strech the glide can also be an option....
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Old 2nd Dec 2019, 12:49
  #48 (permalink)  
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increased speed into the ground effect, and then using the ground effect to strech the glide can also be an option....
Generally speaking, you're gliding, to make it "over the hedge" to a suitable forced landing area. If the area is flat enough that you could fly in ground effect, you could probably land safely on it there! There is a minor effect of added lift in ground effect, which it momentary if you're gliding. You should be experiencing it during the flare of most landings, so you know what it's like - and it really won't get you anywhere further power off.

On the whole retracting flaps and experiencing an altitude loss.... isn't that mostly a butt feeling? Cause if managing the possible increased speed correctly, and being able to maintain the best glide throughout the retraction, there shouldn't be any loss of altitude?
Aside from a possible engine failure during departure, or approach, why were the flaps extended? Unless the flight manual for your airplane says otherwise, leave the flaps alone as you enter a glide, and extend them only when landing is assured. I would be fascinated to read a power plane flight manual which directs otherwise.

An over riding theme here should be that "best glide" and stretching the glide, and going as far as you can per altitude lost, should not be your primary focus in an engine failure, unless it's simply to make it to the coast, or over the mountains. Arriving to 1/4 mile on final into a tight spot at "best glide speed" is going to demand the most of your skills in power off landing judgement, and the consequences of getting it wrong could be terrible. Better to make a good job into a closer spot if it's available, and have to bleed off speed as you near the landing zone. A judgement error doing that is much less serious.

Of course, there will be occasions where the glide must be optimized to make it to anywhere you could land, so yes, fly at "best glide speed" then. With this in mind, it would be useful to practice power off landings from high final approach at that speed. Demands on skill and precision in the flare will increase doing this!
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Old 2nd Dec 2019, 15:40
  #49 (permalink)  
 
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Originally Posted by Pilot DAR View Post
Generally speaking, you're gliding, to make it "over the hedge" to a suitable forced landing area. If the area is flat enough that you could fly in ground effect, you could probably land safely on it there! There is a minor effect of added lift in ground effect, which it momentary if you're gliding. You should be experiencing it during the flare of most landings, so you know what it's like - and it really won't get you anywhere further power off.
Like I said, never tried it, but was taught it many years ago when I got my license.... Hoping it would safe the undercarriage from going into that ditch short of the runway.

Originally Posted by Pilot DAR View Post
Aside from a possible engine failure during departure, or approach, why were the flaps extended? Unless the flight manual for your airplane says otherwise, leave the flaps alone as you enter a glide, and extend them only when landing is assured. I would be fascinated to read a power plane flight manual which directs otherwise.

An over riding theme here should be that "best glide" and stretching the glide, and going as far as you can per altitude lost, should not be your primary focus in an engine failure, unless it's simply to make it to the coast, or over the mountains. Arriving to 1/4 mile on final into a tight spot at "best glide speed" is going to demand the most of your skills in power off landing judgement, and the consequences of getting it wrong could be terrible. Better to make a good job into a closer spot if it's available, and have to bleed off speed as you near the landing zone. A judgement error doing that is much less serious.

Of course, there will be occasions where the glide must be optimized to make it to anywhere you could land, so yes, fly at "best glide speed" then. With this in mind, it would be useful to practice power off landings from high final approach at that speed. Demands on skill and precision in the flare will increase doing this!
Oh, I agree so much about this, it was merely on the statement of retracting already extended flaps, which could be a misjudgement to extend in the first place. But ofcourse you wouldn't aim for a maximum glide distance if looking for a field, except as you say, have to get clear of very bad terrain, forests, mountains etc.

But sure, rather run out of runway than landing short of it.... better hit something slowly, than fast...
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Old 2nd Dec 2019, 19:02
  #50 (permalink)  
 
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increased speed into the ground effect, and then using the ground effect to strech the glide can also be an option....
... but sometimes a fatal option. A friend of mine was undershooting in a glider and tried to stretch his glide, to avoid the inconvenience of landing off the airfield. He flew in ground-effect over a perfectly landable field and then tried to hop over the boundary fence. He didn’t have enough energy and the barbed-wire sliced through the canopy.
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Old 2nd Dec 2019, 21:34
  #51 (permalink)  
 
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"to legally fly below 500' AGL"
In the UK and US, (but not Irish Republic) you can legally fly below 500', but not within 500' of a person or structure.
I've had many check flights over the years, and I now make sure in advance what the instructor wants.
Some insist on a circuit, some just want me to reach a suitable landing place.
I lost sight of my best choice while flying a circuit in a C172, and had to go for a poorer field. A friend who had to revalidate by test was failed by the examiner for not flying a circuit, but putting the aircraft in a position it could not fail to land on a farm strip.
One in US, one in UK.
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Old 3rd Dec 2019, 01:55
  #52 (permalink)  
 
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Originally Posted by Pilot DAR View Post
I think that despite my great respect for Big Pistons, we're going to disagree on this. I also accept that BPF is probably thinking initial training, where I am talking advanced training, but... For me, the PLF is an exercise in handling the plane to a touchdown. I view the cause check as more an enroute training element. At some point, you're committed to a power off landing. It is at that point, the training to which I refer begins. I train practice forced landings to a touchdown. Of course, I set things up, so there's lots of room, and after the first "surprise", others will be repeated to the same spot. I find it allows the candidate to rejig their perception, and improve by iteration. I agree that the drill can be begun at altitude, and the cause check, and setting up the glide be the first element of the exercise, but sometimes a landing will be the result. However, in all cases I train this, it is to an already experienced pilot, as a part of type training. Aside from knowing the location and function of the secondary controls, the exercise is to accurately manage a rather different handling (usually drag) airplane to a successful touchdown.
For ab initio training the PFL is primarily an exercise in decision making and aircraft management. The glide from 500 AGL to touchdown should have already been taught earlier by first been introduced pre solo and then refined as part of the circuit training post solo. Personally one of my favorite exercises for post solo dual circuit training is to, when traffic permits, extend the downwind so that the the airplane turns final at circuit height on about a 4 mile final. The student is then told to close the throttle when they think they can make their selected touchdown and are not allowed to touch the throttle until they are on the runway.


When I did my PPL my instructor made me do PFL downs to 50 feet AGL. This was great until the flaps 40 would not retract and the grossed out C 150 with a tired engine on a 33 deg day would only climb at 50 feet min. On the way back to the airport we had to turn to dodge power lines, trees, and houses. Each gentle turn stopped the climb. 8 miles later we entered the base leg for our home airport at 200 ft AGL.

At 500 ft AGL it will be completely obvious if you are going to make the intended touchdown point and the aim of the exercise has been achieved, with enough margin to deal with unexpected events.......

With respect to flaps I teach use of flaps the same way I teach use of spoiler for gliders, wait to add flaps when you see overshoot developing ( ie touchdown point is moving down the windshield)
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Old 3rd Dec 2019, 10:42
  #53 (permalink)  
 
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Originally Posted by Big Pistons Forever View Post
This was great until the flaps 40 would not retract and the grossed out C 150 with a tired engine on a 33 deg day would only climb at 50 feet min
That aircraft should never have been equipped with flaps.... or at least have the last notch removed....

It's a fun aircraft by the way.... during my checkride, the assessor decided to have me do the 15 degree flaps, 1500 rpm and stall it..... guess who was taken completely by surprise when the aircraft flipped.... noone told me it would do that during training.

(I passed by the way, he just wanted to see me handle the flip)
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Old 3rd Dec 2019, 12:43
  #54 (permalink)  
 
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This very interesting discussion will benefit any PPL. My flying days are long gone but I vividly remember enough to make one contribution, if I may: nothing can prepare you for the mental shock when the noisy lump out front suddenly goes silent and the aerofoil-shaped Finger of Doom points accusingly above the cowling.

You will go through the drills comprehensively discussed above but few have experienced the drag from a stationary prop and the resulting need to get the nose down immediately to maintain airspeed, even more as you turn around your chosen field. How often do witnesses say that they heard the engine stop, then the aircraft turned and dived into the ground?

The aircraft may require a steep descent to maintain control in the absence of propeller slipstream over the empennage, even steeper when turning finals, to the extent that one may fear diving into the ground. My ex-WW2 instructor would not let me solo the Tiger Moth until I could demonstrate an incipient spin and recovery at 500 ft. I learned later that one of his pupils had spun in on finals.

To the thread's excellent advice may I suggest that anyone will benefit from learning basic aerobatics. As my dear old chum Desmond told me, aerobatics give you the confidence to recognise and recover from abnormal situations -- and they're also great fun!

May our engine(s) always keep running.
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Old 3rd Dec 2019, 18:42
  #55 (permalink)  
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Originally Posted by Geriaviator View Post

..

You will go through the drills comprehensively discussed above but few have experienced the drag from a stationary prop and the resulting need to get the nose down immediately to maintain airspeed, even more as you turn around your chosen field. How often do witnesses say that they heard the engine stop, then the aircraft turned and dived into the ground?

.

Thanks for that reminder that tick-over is very different from stopped - both aerodynamically and psychologically!

Good advice on getting some basic acrobatic training, I will certainly look for a chance to do that.
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