The DC-8s had in flight TR capability
Air Canada had a serious accident because of a premature in flight TR deployment on a DC-8 at Malton in the 1960s, to get the plane down for landing.
The plane landed very hard, the pilot took off again, but the aircraft had received serious structural damage and was lost along with its full load of passengers as it crashed during the go around.
So as SLC I'm a strong proponent of squat switches for passenger jetliners TR.