Heat effect over car parks?

[trinity 09L]

I was going through circuit practice yesterday, not a particular hot day, but at the end of our runway their is a large car park, and the reflective heat upwards gave a squeaky " %&*" moment after a touch and go. With large car parks around other airfields and LHR/LGW etc is this a common factor to neccesarily inform students?

[GrahamB]

I was going through circuit practice yesterday, not a particular hot day, but at the end of our runway their is a large car park, and the reflective heat upwards gave a squeaky " %&*" moment after a touch and go. With large car parks around other airfields and LHR/LGW etc is this a common factor to neccesarily inform students?

I think you'll find that this was not 'reflected heat' but the turbulence caused by the differential warming of the air over a heat absorbing surface.

The air heats up and starts to bubble upwards, to be replaced by air moving across from cooler surfaces. It's not at all uncommon, and yes, at low level and slow speeds it can be disconcerting. Its evil sister, sinking air, can catch you out on final approach so best be prepared for it whenever it's sunny.

On a bigger scale, It's also a cause of cumulus clouds.

[Gertie]

You can get a thermal off a tarmac runway too which can be a bit disconcerting. Once (whilst still I student I think) I got blown up in the air and sideways as I came over the runway on the approach ... go-around whilst I tried to work out what had happened. Bit scary being banked at a silly angle a few feet above the ground.

Same on the second approach - I was expecting it this time but wasn't able to recover enough to land.

Third time round I went for the grass runway and landed without problem.

[KNT754G]

All sorts of surfaces can produce this effect.

I was once trying to teach a student circuits but when one is crossing the sand dunes on approach to 10 at Blackpool with idle power, 30 degrees of flap, correct speed and a POSITIVE rate of climb it becomes a trifle tricky.

Very hot day and slight wind across the dunes increasing the lift on short final.