Thermalling With Others

Thermalling With Others - Nigel Page

Nobody owns a thermal but aside from any considerations of safety when joining one located by another pilot we have at least a moral responsibility not to jeopardise that pilots use of it. There is much to be gained from group flying and considerate use of a thermal by one pilot which has already been located by another should enhance it's value to both.

Joining A Thermal Already In Use

Clearly the first thing is to thermal in the same direction. This seems to help even if thermalling a nearby core because the cores will often converge. If there is a very large vertical separation between pilots using the same thermal this may not seem important but a third pilot joining a thermal with two pilots already Thermalling in opposite directions will literally not know which way to turn.

Secondly we have to decide which part of the circle to join. If joining with a large vertical separation this is not too critical and can be adjusted once both pilots are established in the thermal. However if, as in many situations, the vertical separation is poor it is vital that the joining pilot takes great care. The optimum position to aim for is the opposite side of the thermal to the other pilot and to achieve this it may be necessary to delay entering the thermal. This may seem wasteful to some pilots but there is more to be gained from delay followed by co-operation than by conflict followed by distrust.

Problems When Joining Thermals

Arriving on a collision course with the pilot already Thermalling can be the result of:

· Mis-timing the arrival and ending up in the same segment of the circle as the pilot already thermalling.

· Failing to circle on the same track as the pilot already thermalling.

The answer to both problems lie in a good entry to the thermal. The best way to enter a thermal is at a tangent at a point at which the Thermalling pilot would be heading directly away from you. This is the point to aim for, not the centre. If you seem likely to arrive in the thermal on a collision course with the aircraft already thermalling simply bear away from the thermal, allow the other aircraft to pass, then enter the thermal behind it. Try to avoid sharp turns which are inefficient, disorienting and unnerving for the other pilot.

A pilot aiming for the centre will have to either weave about or cross the track of the other pilot and then perform a tight turn to get onto that track. It is extremely difficult to do this without interfering with the other pilot.

Maintaining Contact

Often other pilots in a thermal are better than a variometer for staying with a core. If you watch a large group of seagulls thermalling you will see them sometimes stay close together and sometimes spread to look for better lift. Most thermals seem to waver about as they climb and continual re-centreing is usually needed. When you are flying opposite another pilot this is usually accomplished by noting if he or she climbs relative to you at one part of the circle. You should then move the centre of your circle towards that area by straightening your turn for a short period at the appropriate part of the circle. The other pilot should have seen that they were outclimbing you at that time and adjust their circle accordingly.

Thermalling With Hang-Gliders

Similar principles apply to thermalling with hang-gliders but the following should be noted:

· Hang-gliders are faster than paragliders and in order to keep on the opposite side of a core to a paraglider they may have to fly a larger radius turn (or you a tighter one). In a small fast core they may turn very tightly like a dog chasing its tail. If you encounter a hang-glider thermalling this way you will have to join either well above or below it.

· In a steeply banked turn hang-glider pilots cannot readily see the space that they are turning into. You may observe experienced pilots briefly bank away from a thermal to peep under the wing. To keep where hang-glider pilots can see you in a thermal you may have to stay below them but the best way is to out-thermal them and leave them behind!

· If you're drifting with a thermal you can 'mark' it for a hang-glider pilot who can then look for better lift elsewhere and return to your core if unsuccessful. With a better speed and glide angle a hang-glider can search a greater area faster than a paraglider. When you see the hang-glider find better lift you can leave your core and join in.

None of us are perfect and the fickle nature of thermals is such that conflicts will occasionally occur. Despite this it is great fun to thermal with a considerate pilot and the benefits of group flying make co-operation well worthwhile.