Glide approaches
There is a major difference between failure to find lift and engine failure, ie. a sink rate of a 100'/min or so compared to 800'/min.
In a glider at 2000' AGL, you have some 8-10 minutes to pick out a field within 4-5 miles and 200 yards is plenty long. A well managed landout is a leisurely process.
If the donk quits at 3000' AGL you will be at your 1000' key point in 2.5 minutes which has to be within about 2 miles plus you need more like 400 yards.
When I have to fly low, I find myself picking out fields and staying within reach.
As for difficulty of judging approaches, I've always found steeper approaches easier.
Getting the sight picture of a tight approach well burned into the brain is good preparation for that day when you might need it.
In a glider at 2000' AGL, you have some 8-10 minutes to pick out a field within 4-5 miles and 200 yards is plenty long. A well managed landout is a leisurely process.
If the donk quits at 3000' AGL you will be at your 1000' key point in 2.5 minutes which has to be within about 2 miles plus you need more like 400 yards.
When I have to fly low, I find myself picking out fields and staying within reach.
As for difficulty of judging approaches, I've always found steeper approaches easier.
Getting the sight picture of a tight approach well burned into the brain is good preparation for that day when you might need it.
To those who think glide approaches should be the norm..have you really considered the matter in the 21 st century? Bit like accepting GPS?!
For example have you considered the difficulty fitting it in with other traffic? Have you ever been trying to teach it and been frustrated at the time spent trying to find a suitable gap in traffic? That is the reason for telling Air Traffic you require one!
For those of you who do it every time....do you really subject your novice passenger/grandmother to a sudden and total reduction in engine power on base leg and then what, to them, appears to be a suicidal dive to the Airfield? Do you?
For those who operate from private strips (frequently small and often demanding)...do you really do it when a short field "performance" type approach is really what is required?
For those who fly heavy complex singles..do you ever do it in one of these types? Do you?
For those who fly twins...ever do one in a twin?!
For those operating from Regional airports...how do you manage them all the time? Same applies to those operating from busy GA fields.
And what does this bog standard glide approach "training" achieve when the performance may be nothing like a genuine engine failure which can vary from a catasphophic failure to a bit of carb ice, all of which may require differing actions!
So, who is doing them as a matter of course and what are they really achieving?
UV
For example have you considered the difficulty fitting it in with other traffic? Have you ever been trying to teach it and been frustrated at the time spent trying to find a suitable gap in traffic? That is the reason for telling Air Traffic you require one!
For those of you who do it every time....do you really subject your novice passenger/grandmother to a sudden and total reduction in engine power on base leg and then what, to them, appears to be a suicidal dive to the Airfield? Do you?
For those who operate from private strips (frequently small and often demanding)...do you really do it when a short field "performance" type approach is really what is required?
For those who fly heavy complex singles..do you ever do it in one of these types? Do you?
For those who fly twins...ever do one in a twin?!
For those operating from Regional airports...how do you manage them all the time? Same applies to those operating from busy GA fields.
And what does this bog standard glide approach "training" achieve when the performance may be nothing like a genuine engine failure which can vary from a catasphophic failure to a bit of carb ice, all of which may require differing actions!
So, who is doing them as a matter of course and what are they really achieving?
UV
Last edited by UV; 12th Dec 2007 at 20:52.
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>>>>>>>>>>For those who operate from private strips (frequently small and often demanding)...do you really do it when a short field "performance" type approach is really what is required?<<<<<<<<<<<,,
Sorry, must be my old age. Can you define what a "short field performance approach" is
Sorry, must be my old age. Can you define what a "short field performance approach" is
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don't expect the prop to be stationary. It will be windmilling
What I've heard is that a stationary prop will cause less drag than a windmilling one, but in order to get the prop really stopped you've got to slow down to something very close to stall speed, usually. That's not something you're going to do with an engine failure, unless you've got steel nerves and plenty altitude to spare.
My prop stopped completely - probably due to the fact that we had just gone through to full power at the beginning of a go-round, so were indicating 60-65 knots.
From what I noticed, [in between my cursing, hoping there really IS no hell, and thumping my student] we glided better.
Or maybe it was just that time slowed down. Who knows.
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Oh, I almost forgot:
I beg to question what kind of Pilot you are if you imagine this would ever happen.
I always - and I mean ALWAYS - tell my pax what is going on with the aircraft at any phase of flight - especially when I'm about to reduce power. If they know what to expect, and see me looking completely relaxed, then I'm not "subjecting" them to anything.
So, what you're saying then is because it MAY not be like the real thing, we shouldn't practice them?
Best we stop teaching/practising stalling, spin recovery, precautionary landings, forced landing without power as well.
For those of you who do it every time....do you really subject your novice passenger/grandmother to a sudden and total reduction in engine power on base leg and then what, to them, appears to be a suicidal dive to the Airfield? Do you?
I always - and I mean ALWAYS - tell my pax what is going on with the aircraft at any phase of flight - especially when I'm about to reduce power. If they know what to expect, and see me looking completely relaxed, then I'm not "subjecting" them to anything.
And what does this bog standard glide approach "training" achieve when the performance may be nothing like a genuine engine failure which can vary from a catasphophic failure to a bit of carb ice, all of which may require differing actions!
Best we stop teaching/practising stalling, spin recovery, precautionary landings, forced landing without power as well.
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My prop stopped completely - probably due to the fact that we had just gone through to full power at the beginning of a go-round, so were indicating 60-65 knots.
Also, what was eventually determined to be the cause of your engine stoppage? Unless it was a catastrophic failure physically blocking the rotation, I would expect that at typical approach/go around speeds, an engine would remain windmilling even if there's no fuel at all going into the cylinders.
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UIV I'm a bit baffled - why would a glide approach cause any of the difficulties you quote?
You might be a little higher at the start but given the variability of apporaches I doubt anyone would notice.
You fly pretty much the same speed so how is 'fitting in' a problem?
As for plummeting? Are you a newspaper reporter? Do you treat your engine that way? Cos I certainly never do.
What do I achieve by doing them? I improve my aircraft handling skills, I give myself many more options if the engine every does fail, I maintain a level of currency in terms of judgement which flying an engine assisted PAPI apporach does not exist - actually I have fun too!
You might be a little higher at the start but given the variability of apporaches I doubt anyone would notice.
You fly pretty much the same speed so how is 'fitting in' a problem?
As for plummeting? Are you a newspaper reporter? Do you treat your engine that way? Cos I certainly never do.
What do I achieve by doing them? I improve my aircraft handling skills, I give myself many more options if the engine every does fail, I maintain a level of currency in terms of judgement which flying an engine assisted PAPI apporach does not exist - actually I have fun too!
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Glide or powered isnt an argument that can ever be won, too many opinions mostly based on folk lore. The aim of a PPL is to be able to fly to other destinations and at many airfields it just may not be appropriate to fly a glide approach.
As already stated, glide approaches stems from Tiger Moth days when a/c did not have flaps and engines were not so reliable.
What is more important is the ridiculous wide circuit patterns flown by some schools.
As already stated, glide approaches stems from Tiger Moth days when a/c did not have flaps and engines were not so reliable.
What is more important is the ridiculous wide circuit patterns flown by some schools.
I fly behind a 66 year old engine (it has been rebuilt a few times) and I prefer to slow down at the end of the downwind and then make a curving approach at idle power with full flap (effective) and using sideslips as necessary to position for the end of the runway. Carb heat isn't an issue as it is automatically on when the throttle is set for anything less than full power. I always feel that I've let myself down if I have to touch the throttle.
I feel that glide approaches should be practised as you are effectively practising a PFL without any possibiliity of breaching the 500' rule.
One instructor I flew with had a great way of focusing the attention of his student. He'd get the student to position the aircraft over the middle of the airfield (3 runways ex B-24 base) and then turn the magnetos off. Certainly got the attention of the occupier of the LHS.
I feel that glide approaches should be practised as you are effectively practising a PFL without any possibiliity of breaching the 500' rule.
One instructor I flew with had a great way of focusing the attention of his student. He'd get the student to position the aircraft over the middle of the airfield (3 runways ex B-24 base) and then turn the magnetos off.
Certainly got the attention of the occupier of the LHS.
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Ratherbeflying: I think you rather overstate the difference - 1kt min sink from a k13 is on the ambitious side, and I'm pretty sure the 172 doesn't do 8kt down at best glide - not with both wings attached in any case. I'd also argue that 2k is rather high to have picked your field, but that's beside the point.
Realistically there are a multitude of approaches between the idle, full flap glide (steep) and the drag it in over the hedges with the engine working hard against full flap. Surely there's a certain degree of discretion as to what is appropriate for the aeroplane and the circumstances. Being a paranoid type, I tend to err towards the high side on the basis it provides the greater margin of safety. Sure engines rarely fail on short final - but that's little consolation IF it happens to you. I also try to be gentle on the engine. But I'm merely a low hours PPL treading carefully.
Realistically there are a multitude of approaches between the idle, full flap glide (steep) and the drag it in over the hedges with the engine working hard against full flap. Surely there's a certain degree of discretion as to what is appropriate for the aeroplane and the circumstances. Being a paranoid type, I tend to err towards the high side on the basis it provides the greater margin of safety. Sure engines rarely fail on short final - but that's little consolation IF it happens to you. I also try to be gentle on the engine. But I'm merely a low hours PPL treading carefully.
Mark1234, Agreed the 2-seater trainers come down faster and are generally best kept within range of the home field. Fibreglass single seaters have minimum sink in 100-120'/min range.
800'/min is something I'm quite used to seeing in a C-172 at idle, generally with 20 flaps; about the same in a Citabria.
At 2000' in a glider, I'm starting to look for fields, especially as at that level you're generally below the working band. While all the time I'm looking for lift, I do want to have a good field in my pocket by the time I'm down to 1,500. Once I have that the name of the game is to find sufficient lift to get away before I'm down to 800' at which time I've run out of quarters and it's time for the downwind.
800'/min is something I'm quite used to seeing in a C-172 at idle, generally with 20 flaps; about the same in a Citabria.
At 2000' in a glider, I'm starting to look for fields, especially as at that level you're generally below the working band. While all the time I'm looking for lift, I do want to have a good field in my pocket by the time I'm down to 1,500. Once I have that the name of the game is to find sufficient lift to get away before I'm down to 800' at which time I've run out of quarters and it's time for the downwind.
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None of the above is an argument for using the glide approach in favour of a powered approach.
The best approach is the one that brings you over the hedge at safe altitude and airspeed and provides a safe touchdown point.
I went into LHR once in a C172 and they asked me to keep 120 kts for as long as possible to the threshold, I couldnt really say sorry i only do glide approaches!
The only argument I can see for glide approaches are training and practice.
The best approach is the one that brings you over the hedge at safe altitude and airspeed and provides a safe touchdown point.
I went into LHR once in a C172 and they asked me to keep 120 kts for as long as possible to the threshold, I couldnt really say sorry i only do glide approaches!
The only argument I can see for glide approaches are training and practice.
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Just for the record Ratherbeflying I retract my previous - did a checkride in a warrior today and attendant PFL - thermic day, was seeing anything between 500 and 900 down - say an average of 700 down, definately in the ballpark and obviously flaps will worsen the angle (good reason to keep them hidden until really sure!). FWIW I'm also in line with your expanded version of outlanding procedure - most of my XC has been done in the UK where the working band is generally fairly low.
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Backpacker... (sorry for delay don't have internet at home)
Cessna 152, Lycoming 4 cylinder, no catastrophic failure, no fuel blockage.
And, again, the prop definitely stopped and there indeed was NO fuel going to the cylinders - my student had turned it off.
(as anyone who has flown a C152 will know... you cannot see the fuel cock, you can only feel it... and as I cannot fathom any sane reason why my student would turn it off, I did not check it every two minutes.....)
Cessna 152, Lycoming 4 cylinder, no catastrophic failure, no fuel blockage.
And, again, the prop definitely stopped and there indeed was NO fuel going to the cylinders - my student had turned it off.
(as anyone who has flown a C152 will know... you cannot see the fuel cock, you can only feel it... and as I cannot fathom any sane reason why my student would turn it off, I did not check it every two minutes.....)
kiwi chick had the engine recently been overhauled thus giving the cylinders a higher compression ration than a half life engine? Conversly, backpacker, how many hours does the engine in the R2160 have on it?
The one time I had my engine cut on closing the throttle the prop did stop but I was only doing 40mph at 5' above the runway so I didn't have a chance to evaluate any improvement in gliding characteristics
but I did notice the sudden loss of residual thrust. It wasn't the best landing of my life 
The one time I had my engine cut on closing the throttle the prop did stop but I was only doing 40mph at 5' above the runway so I didn't have a chance to evaluate any improvement in gliding characteristics
but I did notice the sudden loss of residual thrust. It wasn't the best landing of my life
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Just my pennyworth.. During my PPL training on Cherokees in South Africa, shock cooling was not really a problem with air temps regularly above 25 degrees. So we did glide approaches on every landing.
I queried whether the prop would stop with an engine failure, so we stopped the engine overhead the airfield to see what would happen. Result it kept going until approx 60 knts, thereafter we followed the checklist and cracked open the door. Can't remember the actual rather high rate of descent, but the sight of that prop blade sticking up in front of me was quite intimidating.
I queried whether the prop would stop with an engine failure, so we stopped the engine overhead the airfield to see what would happen. Result it kept going until approx 60 knts, thereafter we followed the checklist and cracked open the door. Can't remember the actual rather high rate of descent, but the sight of that prop blade sticking up in front of me was quite intimidating.
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Conversly, backpacker, how many hours does the engine in the R2160 have on it?
Haven't had the nerves yet to pull ICO at FL55 in the aerobatics area yet to see what happens, record glide performance etc. Problem compounded by the fact that at my home airfield (Rotterdam), the CTR only extends to 3000', with the class A Schiphol TMA on top, and these sorts of stunts are generally not appreciated there. And with the end of the year looming at work, and things to do in the weekends, I've got the feeling that my flight last weekend was the last for this year.
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Haha, it is quite unnerving isn't it? Looking at it, thinking "I'm not supposed to SEE you..."
I went and did a deadstick with our CFI afterwards from overhead the field, and I don't recall that we had any problems getting it to stop? Maybe we pulled back to nearly a stall, I can't recall.
Amazing how much calmer I was with someone more experienced beside me - mind over matter?! I mean, there was no way we were going to miss the runway - even I'm not that bad!
I went and did a deadstick with our CFI afterwards from overhead the field, and I don't recall that we had any problems getting it to stop? Maybe we pulled back to nearly a stall, I can't recall.
Amazing how much calmer I was with someone more experienced beside me - mind over matter?! I mean, there was no way we were going to miss the runway - even I'm not that bad!
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Tell that to the folks who use Lycoming powered glider tugs and they'll brain you!
Keeping power on to allow the rear cylinders to cool slowly makes a huge difference to the mean time between failures. Now, it may not be relevant of a relatively cool circuit, but it certainly does apply to engines which have warmed up nicely in a high power climb - just 20-30 seconds of so of level flight before pulling back the throttle and subjecting the cylinders to increased airflow in the descent can make all the difference to engine life.
Keeping power on to allow the rear cylinders to cool slowly makes a huge difference to the mean time between failures. Now, it may not be relevant of a relatively cool circuit, but it certainly does apply to engines which have warmed up nicely in a high power climb - just 20-30 seconds of so of level flight before pulling back the throttle and subjecting the cylinders to increased airflow in the descent can make all the difference to engine life.