Having received the runway in use and circuit direction when close to an airfield I do some hurried mental gymnastics to work out how to approach for a standard overhead join. I recently discovered the SD “Make Approach” function and was very pleased to see there is a “Standard Overhead” join option.

The first time I used it in the air was arriving at Enstone. I selected Make Approach, Runway 26, Standard Overhead. A nice big purple arrow appeared “for guidance on where to join” (to quote the SD video tutorial). I started heading towards the arrow, but after even more hurried mental gymnastics realised I would be joining from the opposite direction to that required and made corrections.

I have since used the same function arriving at other airfields and they are all wrong. According to SD a standard overhead join is approached from the dead side, with descent on the live side to join the circuit. According to the CAA a correct standard overhead join is approached from the live side, with descent on the dead side to join the circuit on the crosswind leg.

This is more than just misleading it is plain wrong. At worst, a pilot following SD’s guidance would conflict with a pilot doing a ‘correct’ overhead join. At best he would be joining high on the downwind leg and making a total hash of the circuit.

I’ve attached below a screenshot from SD and a CAA diagram of a standard overhead join to illustrate my point. Comments welcome – is there something I’m missing here?

Chris

Whatever opinion is held about it, I would hope that everyone could agree the UK CAA prescribes something called a Standard Overhead Join. I have already posted two illustrations of this from CAA publications, and here is a third from one of their safety posters at https://publicapps.caa.co.uk/docs/33/ga_srgwebStandardOverheadJoinPosterJan09.pdf



Note the initial blue line in the diagram, and the key bottom right. The blue line is defined as the “joining phase”. The starting point of the joining phase is always on the live side, and it always continues towards the dead side. It does not matter a jot from which point of the compass the aircraft is arriving – the ideal (CAA prescribed) starting point for the overhead join is always in the same place for a given runway and direction. If an aircraft joins somewhere else it is not a “standard overhead join”.

The descent phase (yellow line) is on the dead side. Turn left and descend to enter a left hand circuit on the crosswind leg. Turn right and descend to enter a right hand circuit on the crosswind leg. The key point is you are by then no longer “joining” – you have already done that (the blue line). That’s not my opinion, it’s what the CAA prescribes. I cannot see how anyone can argue any of the above as the CAA makes it all absolutely clear.

The SD arrival function knows the runway in use (the user selects this). Therefore it could very helpfully depict the ideal place and direction to “join overhead”, which would be the same whatever direction the join is from. It's then up to the pilot to arrive there pointing the right way, but at least she knows where she's heading for. For me the best way to represent this would be a big fat purple arrow, with – optionally – its pointed end turned in the circuit direction. Very similar to what SD depicts at the moment, but (correctly) pointing from live side to dead side.

There are several reasons I am labouring this issue. For me, working out the orientation to join overhead (in the prescribed CAA manner) on receiving runway information is quite taxing in an already high workload phase of flight. SD is generally of enormous help to me but lets me down on this one point.

Despite the rationale given for it being correct (such as “the purple arrow shows your entry into the circuit [Ed: therefore at circuit height, way below joining height] from after you have joined overhead and descended dead side”), which may or may not be true, it is not correct “guidance on where to join” (SD tutorial) for a Standard Overhead Join. I like SD to be accurate.

Finally, it seems to me that it’s a simple thing to correct – or ‘improve’ if you prefer. The purple arrows for the other types of join (Downwind, Downwind 45, Base, Long Final) are all spot-on! All the info is there so why not make the Standard Overhead join correct as well? It was said it can't be done because the direction the aircraft is coming from is not know. As explained above - the direction does not matter! The arrows are drawn correctly for the other four types of join despite also not knowing the arrival direction.