Glide approaches
 

In the old days they used to do glide approaches all of the time presumably due to the unreliability of engines. Gliders still do glide approaches.

Then we started doing powered approaches, presumably because the airlines need to do powered approaches (on the back of the drag curve) and instrument approaches demand the 3 degree thing.

When did the switch happen in the PPL teaching world?

When things reversed, and engines became more reliable than instructor skills.....

18G,

I read about these in Alex Kimble's book "Think Like a Bird", even in the 50's it seems to be regarded as the old way of doing things. Other than good practice, I don't think I really understand the logic. If anything the engine is less likely to fail at a low power setting during final when compared to any other part of the circuit (carb ice discussions to one side for the moment, that is down to equipment and technique).

Are you suggesting that an aircraft should be in glide range of the runway from any point in the circuit? If so I don't suppose that would be very practical for many airfields. with all the traffic and noice restrictions we have.

Tony,
I guess I am lazy, I fly a tight tight circuit and if i'm on my own and theres no one ahead then i'll chop the thottle and glide from abeam the downwind numbers, delighting from the joy of kissing the numbers and taxiing off at exit 1. It saves time, its quieter and you get loads of circuits per hour (and being constantly s*** scared of the inevitable engine failure I take every chance I can to practise glide approaches). And other than noise abatement why should we land any other way?

If the guy ahead goes so far out I feel uncomfortable I'll cut in (politely) or more likely go around.

Being in glide range of the airfield (or a good alternative) at all times makes me feel better. I'm not sure whether that affects glide or powered approach argument.

Pilot DAR,

I think you may have nailed the argument. However its just as hard to teach a 2 mile final with power as it is to teach a glide approach.

The change started with the replacement of the Tiger Moth as the school training aircraft.

I know one CFI who still teaches and insists on glide approaches on all normal circuits

I was taught glide approaches in the 1970's by ex RAF instructors. Our trusty mounts were Cessna 150s in which one could select 40 degrees of flap and dive near vertically but never exceed 80 mph.

Great fun, and it imbued me with a lifelong aversion to the 'modern' cross country circuit and powered approach.

I once read a book (wriiten many years ago) in which it was suggested that gentlemen should never "motor in". As a result I never have:ok:

Except when piloting things that glide like a brick:eek:

Sir George Cayley

I think it was later than that. Glide approaches were taught to me as being the norm in the 1970's. Still the best way; with power for those who can't judge it properly, as I was taught, or who wish to land very short.

At some point the training reversed to make power the norm. Hence the daft size circuits. Perhaps it was after the CAA, with their fine minds, made a CPL a requirement for instructing. Then students had to pretend they were flying the airliner the instructor probably thought he ought to be flying.

The owner of what was the finest flying club in the world used to say that the three most useless things in a light aircraft were, a step ladder a stiff broom and a commercial pilot. I make no comment about that.

I too, do what 18greens does. I always glide approach if there's nobody else around, or if there's nobody in front of me - for two reasons.

1) I like to get the practice - having past experience with an engine failure at 200ft AGL you can never, EVER be too practised. EVER!

2) I'm lazy at the end of a long working day. I can't be assed flying big circuits and spending five more minutes on finals when it's not necessary.

And I always call "glide approach".

:ok:

Personally I prefer glide approaches, but then I'm a glider pilot ;)

Seriously - having picked up power also, I'm generally uncomfortable with the 'what happens if the donkey coughs' factor on a powered approach, but I'm lead to believe that it's better for the engine - particularly doing circuits, glide approaches = shock cooling, and bad for the cylinder heads.

My preference is for glide approaches, but when it gets cold, the engine needs to be kept warm, especially for a touch and go.

So in cold weather, more flap or sideslip to counter the extra revs.

Calling glide approaches
 

I note with interest the requirement to call glide approaches. Surely the only requirement is to establish circuit priority (unless local rules require glide approaches to be called.)

When does an approach become a glide approach. I've never seen anything written down about what is a normal circuit (how far out, when to turn etc) with exception of the noise abatement approaches. Theres no requirement to call extra wide circuits.

A glide approach in a motor glider could be flatter than a powered approach in a cessna and a powered approach in a pitts will be steeper than a glide in a cessna. What's the reason to call a glide approach?

The comment about shock cooling is noted.

I must admit that calling a glide approach is a new one on me. If there is a particular circuit size or routing that is what you fly. (I've been based at strips for the last 20 years and so have a near religious observance of these things). For a glide APPROACH it will actually have no effect. OK if you're flying a different type of circuit be it low level or a gliding CIRCUIT then fine call it because it will help people work out where you are.

Once you've decided that the throttle can be closed things really will not look a great deal different apart from being a little above the usual 'glidepath'. Actually of course you are on the glide and all the others are flying below it. Which neatly brings us back to go. I try and fly all my approaches as glides and that gives plenty of time to avoid shock cooling by gently reducing power in the earlier part of the circuit.

More important to call flapless approach than glide approach for following traffic otherwise the flapless pilot extends downwind with the following pilot turning base in the normal position and oops we meet near finals.

'Shock cooling' more folk lore!!!!!!!!!!!!!

Much more important to fly the A/C rather than make any of these 'glide approach' or 'flapless approach' calls, none of which I can find any reference to in CAP413.

Flapless
 

Thats another one, why do flapless approaches need to be flatter or go out further than normal approaches? If you have such a surfeit of energy why not just apply less power and maintain the glide path. Given the wide variety of approach methods and variety of ac you do see one mans long final is another glide approach. Talking of steep approaches have you ever followed one of those powered hang gliders.

So the priority is to ensure everyone knows where everyone is and getting a priority of landing established. What value is there in calling glide or flapless?

In a light aircraft at least flapless landings don't require a flatter approach path and the approach profile is so similar to a normal landing that I don't think it's worth calling. A 10kt or so increase in threshold speed is the only difference usually.

Also if you say on the radio: 'Flapless approach' (which I have heard before) it doesn't really help other pilots much....if you are going to extend the downwind...the say so, it's much more meaningful than saying 'flapless approach'.

I'd always call a glide approach...I think the approach profile is different enough to warrant it.

'Shock cooling' more folk lore!!!!!!!!!!!!!

Chit, now I have to go and use black out on all my P&W and Wright radial engine manuals.....

Especially my manual for the C117 because there are many " Warning " notices in that outlining the danger of cylinder choking due to shock cooling.....

....we could get into reverse bearing load caused by high RPM and low manifold pressure but I won't go there now.

If shock cooling is a factor in engine life in big radial engines can someone explain why the laws of physics should be different for other air cooled piston engines?

How about because all the cylinders are exposed directly to the airflow in a radial and not in other layouts as found in most Uk training aircraft, hence the lack of similar placards.

In a well discliplined circuit with max 4 aircraft(which should be an 800 feet oval for my money) everybody would always be in the same position. However the circuit pattern at a lot of airfileds is just a free for all based more on need than organisation and management

How about because all the cylinders are exposed directly to the airflow in a radial and not in other layouts as found in most Uk training aircraft, hence the lack of similar placards.

Well...lets examine air cooled engines.

Do they need airflow evenly past all cylinders to properly cool each cylinder?

Is it possible that because engines such as the little Continentals and Lycomings do not have their cylinders evenly exposed to the air flow like a radial the engine manufacturers require baffling to evenly spread out the airflow to evenly cool all cylinders?

Anyhow this will get us nowhere.