I was indeed going to ask Tonytales about his early experiences with the Varig Caravelle IIIs, one of the features of which was the braking parachute. maybe it wasn't used on JFK's long runways. They were a real nuisance, especially as they were dropped once off the runway, where they might blow about and hold up further movements until they were captured by the base engineer in their van.
When United was getting serious about the Caravelle there were two details the FAA just would not accept. One was the braking parachute in mainstream US airports. The Caravelle with Rolls-Royce Avon engines initially came as the Caravelle III, and then VI-N, and Rolls did a re-engineer of the Avon to include thrust reversers (instead of the parachute), and this was the difference with the VI-R (for reversers) version, which is the one United bought. The other unacceptable feature was the III and VI-N had passenger supplementary oxygen only available as (a limited number of) hand-held units taken round by the cabin crew if required in a depressurisation; the aircraft relied on a lower maximum altitude and the crew performing an emergency descent if pressure failed (an interesting challenge for the cabin crew to be going round asking if you could breathe or not while the nose was down like this - wonder how they trained for this). The FAA absolutely said NO to this, and Sud had to come up with a "proper" drop-down oxygen system on the United and subsequent aircraft. But I wonder how those early Varig aircraft, operating from New York through Miami down to Brazil, were handled in US airspace for this eventuality.
I often wondered if Douglas had sized the fuselage to that of the DC-8 as Boeing did the B737 to the B707, if Douglas would have survived.
The limiting factor in the early short haul jet days was a combination of insufficient engine thrust and handling in engine-out conditions on a twin. This is why the early twin jets, before the 737, were all narrower (5-across) fuselages and rear engines nearer the aircraft centreline. The 737 depended on more powerful versions of the JT8D being finally available, a bigger rudder, and other aspects to make them capable with an engine out. Remember the DC9 was initially designed around earlier, less powerful JT8Ds. Those of you with an aeronautical engineering background can probably explain the details better than me.