Competition Ballooning – Calculated Rate of Approach
The rule (or information) for this task is set out in Chapter 15 of the Event Rules
This task is a Fly In but to add to that you have to try and arrive over the target area at a certain time. This requires not only the flight planning required of a Fly In (see Aerostat Vol. 46 no.5, October 2015) but also the ability to predict how long it will take you from launch to the target area.
You will receive the same information as a Fly In; i.e. the position of the target and the minimum and maximum distances from your launch point (ILP) to the target. You will also receive a map or plan of the various scoring areas and times when these scoring areas are open i.e when markers drops in these areas will be measured. An example is shown below and relates to an airfield used for a CRAT at the World Championships in 2012 in Battle Creek, U.S.A.
Plan provided on the task data sheet for a CRAT
The target is shown yellow and you are given its coordinates (6817 7986). There are 3 scoring areas A, B, C. In this example the tarmac areas between the scoring zones is a no scoring area at all times, including the target itself. The validity time for A was 07:30 – 07:40, 08:00 – 08:10, 08:30 – 08:40. So markers dropped between those times will be measured, those dropped into that area outside that time receive a no result. For B it was 07:40 – 07:50, 08:10 – 08:20, 8:40 – 08:50 and for C was 07:50 – 08:00, 08:20 – 08:30, 08:50 – 09:00. Though not clear from the diagram the closest point to the target is just within area B. So you need to arrive over area B during the times stated.
The briefing should give you accurate weather information including speed and direction at different heights, both forecast and actual, the latter by windreading information on site. The latter should be more accurate but it becomes less reliable the longer the time between its measurement and your actual take off time and distance between the location it was measured at and your ultimate take off location. You will probably need to supplement this with your own assessment of winds with a piball and if possible, with your own windreading equipment. On many occasions the minimum distance from launch to target is only about 2-3 kms away and time periods are of 10-15 mins . This means that with a 6-8kt wind then it will take you less than 10 minutes to get to the target so a take off just a minute or two before the scoring area you are aiming for opens usually guarantees an arrival safely within the validity period. As pilot’s skills have increased then validity periods have come down and minimum distances further away. The comforting (or not) aspect of GPS and moving maps is that once settled into the flight you can look at estimated time of arrival (ETA) at target to reassure you (or not) that the pre-flight planning was correct.
Competition map of the area showing the target, 1km minimum distance radius and our launch point.
In the example, the tasks that morning were set up some 25km away from where the briefing was held due to the wind direction so we needed to drive out some way to our proposed launch area. The minimum distance was only 1km so the British team headed for Homer Road travelling south-east out of Marshall. We all arrived and found a very convenient front yard (lawn) to launch from well in time and the windreading we then took confirmed this was a good spot. The steerage was excellent and wind speeds appeared predictable. We would not have time to launch for the 07:40 – 07:50 slot. The launch period ended at 8:30 so if we took off at the end of the launch period we may be too early for the 08:40 – 08:50 slot so we aimed to take off at 08:08 for the 08:10 – 08:20 slot estimating it would take 12 minutes to get there. We were off at the appointed time but the winds were much slower than originally measured and our ETA at target would be 08:22. This meant aiming for area C and steerage was good enough to achieve that.
Approaching the target area: CRAT, World Championships, Battle Creek, U.S.A. 2012.
As we took off you could see the other 100 balloons all rising from an arc around the target and slowly converging towards that point. I came in to descend close over the grass side of the edge of the tarmac (tarmac was out) opposite the target. This I did but was some 15 metres away. I lobbed the marker towards the edge of the grass and to my dismay overthrew it, landing on the tarmac – no score and not the first time I had thrown out of a scoring area; and probably not the last.
Scoring areas can be made quite complicated and one needs to study the diagram and the timing periods quite closely. In Poland the competition director made two simple scoring; one a 50 metre circle around the target and the other any area outside of that. This is not uncommon practice in that if you time it correctly you can drop on the target but if not you have to drop in the next zone 50 metre away from the target giving a heavy penalty for not arriving on time. Unfortunately the validity periods were written down incorrectly which stated that the 50 metre circle around the target was open at certain times and that outside at the opposing times rather than; as usual, the outside area being open all the time. This meant that if you missed the inner area altogether because of a change in wind direction then you had to fly on until the outside area was open making the penalty even greater. However, when it does work out as planned, it is always very rewarding to pass directly over the target in the middle of the scoring area in the middle of the time period. On the opposite side it is very nerve racking when you will only reach the scoring area within seconds of the end of the time period. For scoring purposes, the timings relate to the release of the marker from the basket and not its arrival on the ground and that time difference can be critical and has been used.
Written by David Bareford
