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## KDR Synoptic Chart

• stilluntitled97
• Topic Author

### stilluntitled97 created the topic: KDR Synoptic Chart

Did the RPL theory exam a couple of weeks back and am preparing a report outlining my knowledge of the KDR's.
One of the KDR's was the synoptic chart. I distinctively remember it being a section of WA and asking what the QNH was at perth. I studied the Bob Tait RPL book and it wasnt shown in there at all so wasnt expecting it in the exam. Can anyone point me in the right direction as to how the QNH is read. Thanks.

• Posts: 2103

### bobtait replied the topic: KDR Synoptic Chart

Isobars on a synoptic chart are usually placed at 4hPa spacing. At least one isobar will be numbered. Go from that numbered isobar in increasing steps of four if you are heading towards a high pressure system or out of a low pressure system, and decreasing steps of four if you are heading out of a high or towards a low, and you will get a reasonable estimation of the QNH at any particular point on the chart. If a point falls between two isobars, you can interpolate.

This is covered in the PPL book which is now renamed RPL/PPL Volume 2. The two books that were once called RPL and PPL are now called RPL/PPL Volume 1 and RPL/PPL Volume 2 respectively. We suggest that students study both volumes before attempting the CASA RPL or PPL exam. This became necessary because CASA seem to be asking questions at RPL level that were normally covered in the PPL book.