Badly judged FL, how to survive?
Join Date: Jan 2006
Location: Tasman Sea
Age: 66
Posts: 60
Likes: 0
Received 0 Likes
on
0 Posts
Used to fly a 172 commercially, mainly scenics, occasional charter, aerial photography. If my pax were a bit nervous/wind was gusty I would do a normal GA 'drag it in with power' approach. For all the rest(90%) I would pull power opposite the threshhold on downwind and fly the rest as a PFL. (Probably a result of learning to fly on 2-stroke ultralights, as well as some gliding)
Result of all this was I was very confident about dealing with an engine failure as most of my approaches were flown that way.
I could nail most approaches so that I didn't use more than 300m of the strip, with no hard braking, and I often used sideslip to get it where I wanted it. The other bonus was that I wasn't worried about the engine failing on base/final. If you approach with power, and it quits on final, you are going to eat the fence!!
Practice makes perfect, and every approach you fly is a chance to practice a PFL.
Result of all this was I was very confident about dealing with an engine failure as most of my approaches were flown that way.
I could nail most approaches so that I didn't use more than 300m of the strip, with no hard braking, and I often used sideslip to get it where I wanted it. The other bonus was that I wasn't worried about the engine failing on base/final. If you approach with power, and it quits on final, you are going to eat the fence!!
Practice makes perfect, and every approach you fly is a chance to practice a PFL.
Join Date: Jan 2002
Location: Aberdeen
Posts: 1,234
Likes: 0
Received 0 Likes
on
0 Posts
Given that the aircraft is a ATL then I'm not sure what is driving the concern. A ground roll of not much over a hundred metres from anormal landing and precious little energy even if you do hit something.
It sounds much more like this is driven by the add 5 knots is good so 10 must be better school of thinking. My aircraft (ch601hd) weighs about the same and even if you hit a wall on touchdown there is enough structure to crumple that I would be very disappointed not to step out of it.
As for a steep semi-stalled apporach - more likely to turn into a proper stall/spin or arrive at a very unfortunate rate of descent if there is any misjudgement or gusts etc - which will really hurt.
Playing with the flaps is probably not a bad plan but it would be better to fly glide approaches and arrive in the right place at the right speed. If it won't sideslip then S turn but really the constant aspect approach is the one to aim for. As many before me have said!
It sounds much more like this is driven by the add 5 knots is good so 10 must be better school of thinking. My aircraft (ch601hd) weighs about the same and even if you hit a wall on touchdown there is enough structure to crumple that I would be very disappointed not to step out of it.
As for a steep semi-stalled apporach - more likely to turn into a proper stall/spin or arrive at a very unfortunate rate of descent if there is any misjudgement or gusts etc - which will really hurt.
Playing with the flaps is probably not a bad plan but it would be better to fly glide approaches and arrive in the right place at the right speed. If it won't sideslip then S turn but really the constant aspect approach is the one to aim for. As many before me have said!
Join Date: Oct 2000
Location: South West UK
Posts: 367
Likes: 0
Received 0 Likes
on
0 Posts
I'm worried about this "semi stalled" approach and late, hard flare idea!
Think about stalling and what it means, if the suggestion is to fly at the maximum lift angle of attack then the glide will certainly be steeper than flying at the best lift/drag angle but; how do you flare and reduce the rate of descent prior to touchdown?
If the wing is already at the maximum lift angle of attack any increase in aoa will redice the lift, ie there is nothing left for the flare! If you chose to fly right on the stall you will hit the ground hard and, almost certainly injure yourself.
You should not consider flying a deliberately slow "semi stalled" approach; fly the right speed and use sideslip and/or s turns to loose height.
Happy landings
3 Point
Think about stalling and what it means, if the suggestion is to fly at the maximum lift angle of attack then the glide will certainly be steeper than flying at the best lift/drag angle but; how do you flare and reduce the rate of descent prior to touchdown?
If the wing is already at the maximum lift angle of attack any increase in aoa will redice the lift, ie there is nothing left for the flare! If you chose to fly right on the stall you will hit the ground hard and, almost certainly injure yourself.
You should not consider flying a deliberately slow "semi stalled" approach; fly the right speed and use sideslip and/or s turns to loose height.
Happy landings
3 Point
Join Date: Jun 2003
Location: EuroGA.org
Posts: 13,787
Likes: 0
Received 0 Likes
on
0 Posts
I think slower than Vbg is OK.
What matters is that you are always faster than Vs.
At any time above Vs, you can do a last-ditch trade of speed for a bit of altitude. At Vs, you are stuffed and the only option is nose-down to pick up a bit of speed.
Vbg is just a figure, and the glide performance doesn't normally vary much for a good few kt either side of that figure. For example if your Vbg is 95kt, the glide range is barely different for 90 or 100kt. But at 100kt you have a lot more spare kinetic energy (than you would have had at 90kt) which you can trade for a bit of extra obstacle clearance at the last moment.
What matters is that you are always faster than Vs.
At any time above Vs, you can do a last-ditch trade of speed for a bit of altitude. At Vs, you are stuffed and the only option is nose-down to pick up a bit of speed.
Vbg is just a figure, and the glide performance doesn't normally vary much for a good few kt either side of that figure. For example if your Vbg is 95kt, the glide range is barely different for 90 or 100kt. But at 100kt you have a lot more spare kinetic energy (than you would have had at 90kt) which you can trade for a bit of extra obstacle clearance at the last moment.
Join Date: May 2007
Location: Texas, USA
Posts: 8
Likes: 0
Received 0 Likes
on
0 Posts
My question would be - If there is no viable place to land what are you doing there in a single engined airplane.
Flying where there is no place to land means that you have thought about the consequences and have already decided that at the very least you are willing to destroy the aircraft and risk injury and death if there is a problem.
If you are willing to take that risk then deal with the consequences. If you haven't thought of it that way then you should think about the primary duty of the pilot which is to conduct a safe flight and plan accordingly.
Your limitations and those of the aircraft enter into the equation and must be taken into account.
You also have a duty to those on the ground to not place their lives and property at risk for your enjoyment.
Now for a suggestion on control of glide path.
Each aircraft has a speed for max L/D for a particular weight. You should fly above and below what is usually best rate of climb ar low power settings to determing this point. You can "see" and feel this point with enough experience as the angle of attack changes a little bit here.
If you fly your approach slightly slower than this speed you have options that you would not otherwise have.
If you are flying into the wind (as you should be when making an emergency off field landing) you can slow up slightly to land shorter and you can drop the nose to best L/D to streach the glide. If the wind is higher lowwering the nose more will allow you to penetrate into the wind better for each lost foot of altitude up to the point where the additional drag offsets the gain into the wind.
I would suggest that some training in gliders would be of use since every landing is made dead stick.
Good luck and think about where you are and the consequences of your decisions before hand.
Flying where there is no place to land means that you have thought about the consequences and have already decided that at the very least you are willing to destroy the aircraft and risk injury and death if there is a problem.
If you are willing to take that risk then deal with the consequences. If you haven't thought of it that way then you should think about the primary duty of the pilot which is to conduct a safe flight and plan accordingly.
Your limitations and those of the aircraft enter into the equation and must be taken into account.
You also have a duty to those on the ground to not place their lives and property at risk for your enjoyment.
Now for a suggestion on control of glide path.
Each aircraft has a speed for max L/D for a particular weight. You should fly above and below what is usually best rate of climb ar low power settings to determing this point. You can "see" and feel this point with enough experience as the angle of attack changes a little bit here.
If you fly your approach slightly slower than this speed you have options that you would not otherwise have.
If you are flying into the wind (as you should be when making an emergency off field landing) you can slow up slightly to land shorter and you can drop the nose to best L/D to streach the glide. If the wind is higher lowwering the nose more will allow you to penetrate into the wind better for each lost foot of altitude up to the point where the additional drag offsets the gain into the wind.
I would suggest that some training in gliders would be of use since every landing is made dead stick.
Good luck and think about where you are and the consequences of your decisions before hand.
The Original Foot
Join Date: Aug 2006
Location: Chesterfield
Posts: 145
Likes: 0
Received 0 Likes
on
0 Posts
An answer
I was unconcious as a result of a freak accident completely beyond my control. During this time, the well trimed plane glided towards a city, I woke up just in the nick of time to recover the situation, unfortunately the unable to restart the engine...
Join Date: Jan 2002
Location: Aberdeen
Posts: 1,234
Likes: 0
Received 0 Likes
on
0 Posts
Well if a constant aspect, constant rate of approach is too difficult then one with a non-constant vertical aspect and rate should be really interesting.
Smacks of some of the crazy flying routines I've seen (and lousy approaches is strong wind!)
Smacks of some of the crazy flying routines I've seen (and lousy approaches is strong wind!)
Join Date: Dec 1999
Location: Oop North, UK
Posts: 3,076
Likes: 0
Received 0 Likes
on
0 Posts
Would it be possible to I believe "yoyo?", or, "vertical S-turn?"
Descend a bit, up a bit, repeat wasting energy on the unfair conversion rate?
Descend a bit, up a bit, repeat wasting energy on the unfair conversion rate?
Join Date: Jun 2004
Location: Surrey
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
Newbie here! (read: freshly minted PPL)
Once during my training the instructor pulled the throttle for a PFL, which was > 1200ft AGL on a short final position with "Greatest field ever" ... I think it was actually a farm strip. So I nearly wet myself for having spotted it, confirmed tiny headwind, but how to get in? Ended up picking another field in a panic because I was going to touch down at the far end of said strip if I went for it. (As much as I love the sideslip, even that wasn't gonna do)
Afterwards the instructor asked why I didn't go for the one that was straight ahead. "Too high", I said. "What about an orbit?", he asked? At first I thought he meant a overfly, turn crosswind, turn base, then glide approach. But even I could tell there wasn't enough height for that one. Then I realised he meant doing an orbit RIGHT THERE, on short final, at best glide speed.
I guess you'll have to practice doing a 10deg bank at Vbg from a very safe height to see exactly how much you'd lose in perfect conditions during one complete orbit, and various degrees of head and cross wind.
Any mileage in this one, or a widow maker?
SF78
Once during my training the instructor pulled the throttle for a PFL, which was > 1200ft AGL on a short final position with "Greatest field ever" ... I think it was actually a farm strip. So I nearly wet myself for having spotted it, confirmed tiny headwind, but how to get in? Ended up picking another field in a panic because I was going to touch down at the far end of said strip if I went for it. (As much as I love the sideslip, even that wasn't gonna do)
Afterwards the instructor asked why I didn't go for the one that was straight ahead. "Too high", I said. "What about an orbit?", he asked? At first I thought he meant a overfly, turn crosswind, turn base, then glide approach. But even I could tell there wasn't enough height for that one. Then I realised he meant doing an orbit RIGHT THERE, on short final, at best glide speed.
I guess you'll have to practice doing a 10deg bank at Vbg from a very safe height to see exactly how much you'd lose in perfect conditions during one complete orbit, and various degrees of head and cross wind.
Any mileage in this one, or a widow maker?
SF78
Last edited by Spitfire78; 1st Jun 2007 at 17:10. Reason: spelling
I was taught to use the flaps to 'make the field'. So no flaps for a forced landing unless you need to use them to stop you overshooting. Obviously this requires some forward planning and isn't much use in an 'over the hedge' scenario.
Join Date: Apr 2007
Location: UK
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
Spitfire: Yes, orbits can be useful, but we're talking a fairly significant height loss for every 360 deg of turn. Will vary according to the AoB you use, generally, the more AoB, the less the height loss (and potential for the wind to displace you laterally). However, even up at 60 deg AoB ,where most GA pilots seem to think the wings will fall off, we're still talking height loss so significant that you wouldn't even think about it on an EFATO. You may well think about a turnback though, if suitably trained and with, say, an absolute minimum of 500'agl to play with. However:
DO NOT EVEN THINK ABOUT A TURNBACK UNLESS YOU ARE THOROUGHLY TRAINED AND CURRENT IN THEM.
Because otherwise you'll die. Just like that.
DO NOT EVEN THINK ABOUT A TURNBACK UNLESS YOU ARE THOROUGHLY TRAINED AND CURRENT IN THEM.
Because otherwise you'll die. Just like that.
Join Date: Jun 2004
Location: Surrey
Posts: 21
Likes: 0
Received 0 Likes
on
0 Posts
Knight,
Understood ... but we're not talking about EFATO, are we ? I thought the original question was regarding a forced landing, with only one field as an option, and finding yourself high and fast.
SF78
Understood ... but we're not talking about EFATO, are we ? I thought the original question was regarding a forced landing, with only one field as an option, and finding yourself high and fast.
SF78
Thread Starter
Join Date: Jan 2007
Location: Pembrokeshire UK
Posts: 343
Likes: 0
Received 0 Likes
on
0 Posts
Wow! All the info I need right here on PPRuNe. Particular thanks for disabusing me of the semi-stalled idea. And making every approach a glide approach if possible is also good. 
Join Date: Apr 2007
Location: UK
Posts: 168
Likes: 0
Received 0 Likes
on
0 Posts
VeeTail - I'm sure you don't need me to remind you of this, but for chrissakes don't take evreything you read on here as gospel! My best advice to you would probably be to read everything with an open mind, then go and try ot out in your own aircraft in as benign an environment as possible - away from terra firma at least initially, and fairly obviously always with an 'out'. See what works not only for your aeroplane, but also for you. Many who post here are talking out of orifices other than their mouths, or lack actual experience to back up their thoughts. Listen to all but trust nobody!
Join Date: Sep 2000
Location: UK
Posts: 263
Likes: 0
Received 0 Likes
on
0 Posts
I also fly a slippery aircraft which floats for ever if too fast over the hedge. It took time to learn how to do it thr right way. During that time I just used to raise the flats, thic killed the float. Make sure that it is not the gear that you play with.
