wrote:

The runways are offset so there is scope for an early turn.

AFAICS this is not the case for the Heathrow plans.

International Procedures have to be adhered and this is taken into account
when designing the airfield.

There are procedures that should prevent any incedent from occurring.
However, if something goes wrong then Air Traffic Control would have
little time to react, and I consider that to be a problem.

Did you see the BBC docufake "The Day Britain Stopped"? Their plane
crash scenario is not very realistic under the present situation, but if
a third runway were to be constructed then the risk would increase by
several orders of magnitude.