- That First Cross Country
Before You Go
For the most part your gliding to date has been within a few miles of the airfield. Generally, but perhaps not always, you have been no further than the ability to turn for home and make it back in one straight glide without the help of any more thermals – the “final glide” to arrive at circuit height regardless of the wind. Cross country flying will take you further than that and it is quite exhilarating seeing the country from a different aspect. If it is your “thing”, you can get into racing or long distance or both.
For that first cross country you must have your “C” Certificate (flown a total 20 solo flights including two one hour soaring flights, trained and carried out a safe out landing, been briefed on AEF matters and a number of other exams all of which is set out in MOSP(Ops 002) 10.2.3.)
You are getting some gliding experience now and your next goals are the Silver and Gold certificates; the Silver C Distance is out 50Km beyond the release point AND the take-off point (both relevant for an aero-tow launch). Silver height is a gain of 1,000m (3,281’) above your lowest height after launch, while the third goal is duration of 5 hours. I once managed 5 hours and a few seconds in a Kookaburra but forgot the 8 minutes on aero-tow!
Now, at the discretion of the CFI, you may fly a cross country. Do not expect to do any cross country flying on the spur of the moment. You ought to be planning for it some days, even weeks ahead and discussing the practicalities of it with both the CFI and other pilots who have those experiences. It is very useful to have done a dual cross country (or two) with an experienced pilot before you go off into the wild blue yonder on your own!
On the day, make sure that you have in fact received approval for it from the CFI and the Duty Instructor is aware of your intentions. This will make sure first, that your intentions are known and that your intended route is discussed. You will be expected to make an “Ops Normal” radio call every half hour or so giving your position and height and next turning point.
You should ensure that there is a crew to get you if you out-land and that the trailer has all the necessary unrigging gear in it. It is highly unlikely that an aero-tow retrieve will be feasible. This sort of recovery is frequent north of the Divide but even there isn’t always feasible – plan for a vehicle and trailer.
What to Take With You
Be comfortably clothed, preferably long shirt sleeves and long trousers, head cover, sunglasses, plenty of water in a Camel Back so that you can keep well hydrated hands free. Sandwiches, candy bars and the like aren’t easy to get at letalone eating but they are important for your blood-sugar levels. Empty out the bladder pre-flight and be free of any illnesses. Have your phone fully charged and some tie-down gear.
You can go with paper maps, they still work but there are a plethora of electronic aids available and many are specifically for the gliding world – XC Soar, LX Nav, Oudie and so on. But make sure you know how to use them well in advance of this flight. Don’t try to learn on the job, not on your first cross country especially.
I have not included the business of claiming your flight towards the Silver and Gold certificates that these electronic aids can assist you with – that’s another topic.
Where can you go?
For a start, not above 8,500’. We are in Class E Air Space and with RAAF ESALE having their air space commencing from roughly Mirboo North and with the “steps” west down into Melbourne International having their effects from a bit this side of Pakenham, there are still plenty of options available. You can go higher but you need a specific clearance from Melbourne Centre by radio. You can also go into the ESALE Air Space but a clearance is needed for that from ESALE. An absolute restriction is that you may not go above 10,000’ without Oxygen however good the day and no matter how high the cloud base may be.
Still, North to Labertouche on the south flank of the Great Divide, South East to Yanakie, or North East to Churchill are fair distances and each is just over 50km away. Or all of these: but there are some considerations before you try any of them.
Which Way Do You Start Out?
As a very general rule, it is far easier to head off into wind. The reason is simple, if things get tough, turning for home and running with the wind, gives you a far greater distance over the ground for height lost. Triangle courses are a bit different but one long leg into wind, a shorter one across it then the run home with the wind astern is best.
The weather that will allow you to get the heights needed for any of these trips will of necessity have to be warm to hot with at most 50% Cumulus cloud cover and light winds. The days for those conditions will be with the wind from the NE around to the NW and ideally not above say 15KTS at your cruising height. Winds from the SW may be OK as well but they need to be a bit lighter: as the sea breeze makes its way in from the coast in the afternoon, it will strengthen the existing SW wind and cut off the convection. There is an exception to this but at this stage of your flying it is best to keep things simple. If the cloud base and cloud cover are consistent for as far as you can see and is at or above 3,500 – 4,000’, you have every chance of getting away.
The GFA Met web site gives really good look at the day’s weather. You can see predictions for up to three days and checking on the morning of your flight will be very close to the reality encountered – thermal strengths, cloud base, winds at various heights and if any changes are expected that might cut everything off.
How Fast Do You Fly?
Here some specifics about speeds to fly. Off the launch, checks done and in the very first thermal over the airfield, your best thermalling speed is the Min Sink Speed off the placard which is out of the Flight Manual. For both the Twin and the Single Astirs, the specific speeds to fly are weight dependent but a whole host of other factors come into play as well.
For both aircraft, the best thermalling speed is around 45KTS. If you are in the Astir CS, you can in fact do well at 40KTS, but any slower with large bank angles puts you too close to the stall. For the Twin Astir (solo), its Vs is still around 40KTS S&L and you will be unable to fly much less than 45KTS anyway. For both aircraft, it becomes a juggle with the strength of the thermal (or the shrillest noise from the Vario!) and you turning in it to get the best lift.
In your first thermal, it is wise to take it as high as you can possibly go. Don’t go looking for better thermals yet. Get up to as close as you can to cloud base first. On your way up, you can survey the rest of the clouds and work out how well your plan from the ground matches the reality around you.
On approaching the top of this climb, work out your track to your first destination. If you have set a specific route – say to Loch or even just Korumburra, in that last turn in the thermal, gain as much speed as possible so that you leave it still in lift AND at cruising speed aimed at your next destination. As soon as you leave this thermal you will enter sink so if you go out with plenty of energy you will cross the sink boundary and go into benign air more quickly and loose less height or possibly even none.
The Best Glide angles for both aircraft are close to the same, though again depend on a host of factors. How clean the wings are, how well you trim the glider, and how steadily can you fly are the main criteria but around 52 – 55KTS in STILL AIR is the speed that will give a glide angle of around 38:1. In other words, for every 1,000’ above ground, you can fly 11KM: for 3,000’AGL 33KM and so on.
From Loch back to the airfield is 19KM and to have 800’ on downwind for your circuit, you would need to be at about 3,000’ (AMSL – altimeter height). From Inverloch it is the same 3,000’. From Mirboo North is nearly 30Km so about 3,500’ or 4,000’ for a better margin. With headwinds in each of these cases you will require greater heights and maybe an extra thermal.
Coming home, fly back as close as possible to the way you went out but always go for the best clouds that will get you home and that may be a more circuitous route.
All these figures are based on nil wind. Flying with the wind astern of you allows you to slow down a little below Best Glide Speed but there is no real gain for it. However, in a headwind and one above 15KTS, it is wise to increase your air speed by about half the wind speed.
So What Are The Best Speeds?
The name of the game is to conserve the energy the glider has. Leave lift at the highest speed you can manage and once out of that thermal, use the speed to cross the sink boundary and then to fly to the next thermal at Best Glide Angle speed. When you meet your next thermal, use your higher than Min Sink/Thermalling speed to climb while turning into its lift – gain height from bleeding off cruise speed and then use the energy of the thermal to lift you yet higher.
These days, there are many programme applications for phones and tablets (some noted earlier above) that have it all worked out and will give the precise number for the air you happen to be in at any time. They are the way to go nowadays. Even so the Variometers in our gliders are capable of giving good readings on averages. The stronger the average thermal strength, the faster you can fly between thermals.
WVJ has a Cruise/Climb switch allowing you to fly at best speeds based on the Varo’s actual readings and many of the modern programmes also have similar applications built in giving actual speeds to fly in the conditions you are in at any one moment. The trap with these is that you can end up continuously adjusting your speed without achieving a steady speed. What you get is a high workload for low return. By far the best is to pick a fair speed based on the average strength of the thermals and stick to it between thermals. The figure below is for a 15m ballasted glider but is representative of our aircraft.
Notice for example that increasing your average thermal strength for the day (i.e., picking stronger thermals) from 3 knots to 4 knots will improve your overall speed from 100 km/hr to 110 km/hr (Y-Axis). Please remember that these achieved rates of climb will only be two-thirds of the peak reading you see on your Vario average but your cruising speed can go from around 75KTS to 85KTS. (Source: Bruce Taylor, GFA Coach, 2011)
But for the Luddites among us, here is a simple solution. If the thermals are only good for up to 2KTS, you probably aren’t going to get high nor far away anyway. In the 3 – 5KTS average range, i.e. you have been getting bursts up to 8KTS, then it is a probably a good day, high cloud base and so you can give it a go. Above 5KTS average all the way, you have every chance of a good flight ahead of you.
Something to remember is that low down, the thermals will be weak, frequently broken and it isn’t until you have climbed significantly higher that your weak thermal becomes stronger and stronger. The first lesson here is that it is always best to stay high, top up your height where the thermals are stronger.
So the speeds between thermals should be at least at Best Glide Angle – 55KTS. If the thermals have been strong (averaging >4KTS) fly faster and check the difference in sink rates between 55 and the new speed – it won’t be much if you are in benign air! After the next thermal, go for another increase and compare your sink rates again. In your early days, it is easier to fly slowly at Best Speed of 55KTS or so. As you get better then you can look to increasing your inter-thermal speeds.
But this is fun! If you can get into a cloud street that is lined up the way you are going, you can get to cloud base and then head off along track but you are still in lift! So use that energy to increase speed and you do this until one of two things happen. The lift may be so strong that even as you increase speed maintaining height just below cloud, you will reach Vra (Max Rough Air Speed). To maintain Visual Flight Rules (VFR) you must stay clear of the cloud. If the lift is still strong enough to further increase your speed, you will climb into cloud or exceed Vra. Neither are appropriate and so your only choice of action is to move out from under the cloud to reduce the lift.
If you get it right, you can still continue along the cloud edges at speed and height but be careful. Going above Vra even if the air has been smooth, it is unlikely to stay that way. Thermals are by nature, turbulent events and Vra is set so that you do not compromise speed and +/-G limits. It is uncomfortable anyway and will stress both the aircraft and you.
The Height Bands
Cross country pilots speak in terms of height bands in which to fly. Assuming you have negotiated your way up to cloud base, then this is the best place to stay. You can cruise faster and all being well, the lift under the streets and clouds will keep you going all day. The thermals here will have grown from the broken ones you may have struggled with before you got up here.
Keeping high is not how it always pans out so if you find the lift decreasing and you are losing a fair bit of height getting to the next clouds – you are now in the mid-band. Slow down to best glide speed and continue on track, don’t deviate more than about 30DEG because a thermal will be there somewhere.
On a clear blue day, no clouds, trying to search for thermals when there is nothing to see is pointless. Flying to a specific point (town, mountain, silo, etc.) is very important in finding thermals. If you don’t have a place to aim for, thermals off to one side or the other will ever so gently (depending on how close you are to them) deviate your intended heading and you will never get into any thermal. So be very aware of the wings moving up or down as you pass near a thermal. There is no harm in doing a quick exploratory turn of say 45DEG for a few seconds to see what may or may not be present. Remember that the Vario has a lag of anything up to 3 seconds before it will squeak and this is where “seat of the pants” flying is probably the best thermalling aid there is!
So you have been trying to find a thermal and none appear, what next? You have lost lots of height, there are probably thermals still around, but not around you. You are in the bottom band now and your number one priority is to find a landing site.
Transition from Cruising to Landing
Your cross country is effectively over when you are in the bottom band. Below 2,000’ AGL your only priority is finding a landing site. Do that properly and you will live to fly another day. The exception might be if you run into a good strong thermal BEFORE you commit to your FUST checks on downwind and in any event not below 800’AGL.
Any thermal below 800’ AGL cannot be well formed, the thermal will be broken, you are already low, and trying to circle in those conditions is hazardous at best and potentially dangerous when you should be concentrating on a safe landing at an unfamiliar site.
Some Precautionary Notes
So, once you venture out past that first thermal on an exploratory trip, you may still be low. And just because you are keen to get away, is no reason not to be very awake to the real chance of having to land out only a very short distance from home.
Once I was caught out low and too far out to get back from an airfield in NSW I had only left a few minutes ago. I could see it, but I wasn’t going to get back to it. I had to make a very rapid transition from the cross-country mode of “this will be a pleasant cruise” to a very serious “Where is a safe place to land going to be among all these rocks the size of houses?” Fortunately a thermal saved me the embarrassment of potentially wrecking a very good day, the glider and myself. For starters, I shouldn’t have flown over an area that did not have a landing site available to me.
If all you do on your first foray away from the airfield, it is a good idea to look at the various paddocks under you to assess their size – based only on size could I land there or not? You will not be able to make an accurate landing site assessment much above 1,500’ anyway. Once you are above say 3,000’ you can relax a bit if the thermals are aplenty and you are on the way to better heights. All this is pretty comfortable and more so if the airfield is within “final glide” home. Make sure you look back to check that assumption though! Then go back to the thermal and keep going.
So if you are on the way up to cloud base, things should stay pretty comfortable and if all is really bright, you can fly under a street or line of clouds given of course that they line up with your route. First time out it may be best to go with the cloud streets. The darkest patch under any cloud is generally the part with the most cloud above it and hence the greatest lift going into it. And of course, the spaces between clouds is where the sink is.
Keep looking at the clouds around you. They can grow very quickly and die just as fast. Aim for the ones that seem to be growing – these may be the days without any formed streets. Watch out for groups of Cumulus clouds that are starting to tower. Generally one of a bunch will start to grow and then start to suck its neighbours into it. Stay away from any rain, it will degrade your glide ratio by as much as half – so from 38:1 to 20:1 and less. The rain goes down and so does the air around it!
Rain clouds can develop in a matter of a few minutes, and in the worst cases, become Cumulo Nimbus, rising to 30 – 40,000’. You must give these clouds the widest of possible berths – 20KM is appropriate. They have been known to destroy airliners: their up- and down-drafts are fierce and violent. A glider will have no chance.
Even though there are many navigation and gliding aids, never lose sight of where you are in relation to the ground and your direction back to the airfield should always be instinctive. Never let the technology do everything, it can and does fail. One day your super smart phone will turn itself off or refuse to play.
The other awareness is of yourself. If the game changes and you are low with no thermals present and having to land, you will be under some real stress. If you appreciate the circumstances have changed, that is a good start. Take a good drink of water – that will hydrate you and also give you a short mental spell. Take some deep breaths and go through a quick relax of your arms and legs. This will take all of 5 – 10 seconds then you can go back to flying safely and thinking clearly.