This should be the rules:
FROM THE UNITED STATES - PERMITTED 02OCT 19 THROUGH 20NOV 19 OR 24NOV 19 THROUGH 12DEC 19 OR 24DEC 19 THROUGH 30MAR 20 OR 01OCT 20 THROUGH 18NOV 20 OR 22NOV 20 THROUGH 15DEC 20 OR 27DEC 20 THROUGH 31DEC 20 OR 05JAN 21 THROUGH 10MAR 21 FOR EACH TRANSATLANTIC SECTOR. TO THE UNITED STATES - PERMITTED 29OCT 19 THROUGH 29NOV 19 OR 03DEC 19 THROUGH 24DEC 19 OR 11JAN 20 THROUGH 07APR 20 OR 01NOV 20 THROUGH 27NOV 20 OR 01DEC 20 THROUGH 24DEC 20 OR 11JAN 21 THROUGH 17MAR 21 FOR EACH TRANSATLANTIC SECTOR.
Minimum stay requirements
TRAVEL FROM TURNAROUND MUST COMMENCE NO EARLIER THAN THE FIRST SUN AFTER ARRIVAL AT TURNAROUND. AND - TRAVEL FROM TURNAROUND MUST COMMENCE NO EARLIER THAN 24 HOURS AFTER ARRIVAL AT TURNAROUND. TRAVEL FROM INBOUND TRANSATLANTIC SECTOR MUST COMMENCE NO EARLIER THAN 7 DAYS AFTER DEPARTURE OF THE OUTBOUND TRANSATLANTIC SECTOR. AND - TRAVEL FROM TURNAROUND MUST COMMENCE NO EARLIER THAN 24 HOURS AFTER ARRIVAL AT TURNAROUND.
Maximum stay requirements
TRAVEL FROM LAST STOPOVER MUST COMMENCE NO LATER THAN MIDNIGHT 6 MONTHS AFTER DEPARTURE FROM FARE ORIGIN.
And availability is pretty good within this dates for these destinations:
- Frankfurt 2090$
- Zurich 2050$
- Brussels 2180$
- Luxembourg 2199$
For London availability seems only to be in November.