"The tower controller subsequently instructed the Air Canada crew multiple times to execute a go-around because he was not certain that a preceding arrival would be completely clear of the runway before the Air Canada jet reached the runway threshold," Gregor said,
Is it still the common use e.g. LGW, where ATC would say, "XYZ continue approach, expect late landing clearance, One to vacate."? It certainly was common in the rush hour of a single runway op, and it would have reduced capacity hugely if not used. Equally, the, "XYZ continue approach, expect late landing clearance, one to depart." Squeezing a landing followed by a departure and another landing into 2 minutes was a great demonstration of teamwork and needed respect by the crews and strict adherence to speed, situational awareness and to vacate PDQ. There were far more successful late landings than GA's.
I remember decades ago, at LHR, where "cleared to land, one about to vacate." was the call. Is it not the case that the commander can land if visual with the preceding traffic and can be certain that they can stop well before the turnoff being used by the preceding? Or has that allowance be rescinded?
The debate about ATC instructions v requests is an interesting one. In USA you can be cleared to land No.5. I'm not sure if you have to be VMC. There you are sliding down the glide with the squadron ahead of you. I assume the philosophy is you are cleared to land if you consider it safe to do below whatever height you choose. EASA & FAA ATC hand-books will tell us. Other regions might have more draconian attitudes.
I remember a medium jet at LGW being given takeoff clearance behind a heavy. The captain was most critical of ATC that the clearance was given <2mins after the heavy. ATC replied that "they could take as long as they wanted; there was no traffic on finals. It was not an order, just a clearance." Similar "cleared to land" is not an order; however a GA is somewhat different. ATC might get a little trigger happy at some places, i.e. the opposite of LGW in rush hour, but I reckon your defence needs to be solid not to comply. If you think you are going to be able to land OK then a couple of "say again's" might delay the call and even reverse it. Ha!