Airborne use of reverse
2 Quotes:
I recall reading somewhere that one of the early jets (DC8?) could reverse two engines for descent control. (Herod)
The Trident could use reverse thrust for emergency descent, 10,000 ft/min, and before touchdown. The C17 can use reverse thrust on all engines for tactical descents at 15,000 ft/min. (Topgas)
On the DC8 it was permitted to use reverse in the air to increase RoD during a descent. This caused great discomfort due to vibration and was not encouraged. In the '70s, It also tempted an upgrading Captain on the DC-9, who had been a First Officer on the DC-8 to attempt airborne reverse thrust when on an overly steep approach to Malaga, although this was not certified on the -9. The result was loss of parts on one reverser, an emergency landing in MLG with unscheduled night stop - and failure of the upgrading.