CAA radiotelephony manual (CAP413) and sailplane operations

The BGA have worked with the CAA to develop guidance material for sailplane operations which has been added to the CAA Radiotelephony Manual (CAP 413).  This is currently in the form of a Supplementary Instruction (CAP413 SI 2020-01) but will form part of CAP 413 in time.  The effective date of the SI is 8th June 2020.

The intention of the work was to clarify to other pilots and controllers the particular nature of sailplane operations and to include some language which might be useful in allowing glider pilots to cross controlled airspace, or to enter controlled airspace to thermal (clearly subject to normal airspace rules, so not Class A).

The SI should be self-explanatory, but the key elements are:

– The introduction and explanation of the phrases “Thermal/Thermalling”, “Climbing in Wave” and “Landing Out”.

– The introduction of the assumption that, if a glider pilot is granted a clearance to cross controlled airspace, the path of the glider might vary by around 30° or 2nm, the altitude will vary, and the glider may stop and climb. If the controller needs to restrict that, they will say so explicitly.

– There are examples of the RT Phraseology given for both an airspace crossing and an entry to thermal.

Other examples of RT Phraseology for controlled airspace access can be found in Parts 3 and 4 of the BGA FRTOL course at

It remains the case that a FRTOL (Flight Radio Telephony Operator’s License) is not required to use a radio in a sailplane, but it is required to communicate with Air Traffic Control units.