In Portugal there is a company, Sevenair that only operates a small airplane, a 19 seats Dornier 228. It flies across all Portugal, North to South, connecting 5 cities, Bragança, Vila Real, Viseu, Cascais, Portimão.
According to their website, Finist’air has flights most days of the week between Brest and Ushant on a 9-seat Cessna Caravan.
OFD in Germany is offering regular flights (scheduled) between Emden and Borkum using a Cessna 172, with 2 pax max.
Norwegian company Lufttransport have a scheduled route between Bodø Airport and Værøy Heliport using the AgustaWestland AW139 helicopter (Værøy Airport has been closed since a Twin Otter fatally crashed). This helicopter has 15 seats. It’s a bit heavier and longer than some small fixed-wing aircrafts, but certainly much narrower. Dimensions from Wikipedia:
Length: 16.66 m (54 ft 8 in)
Width: 2.26 m (10 ft 0 in)
Height: 4.98 m (16 ft 4 in)
Empty weight: 3,622 kg (7,985 lb)
For comparison, the Twin Otter DHC-6 Series 100 has:
Length: 15.77 m
Width: 19.8 m (wingspan)
Height: 5.9 m
Empty weight: 2,653 kg
The Britten-Norman BN-2A Islander is shorter, lower, and lighter yet, but as a fixed-wing aircraft, remains much wider than the AgustaWestland. For most definitions of “smaller”, the Britten-Norman would win, but if you’re looking for the most compact “plane”, the AgustaWestland helicopter flying to Værøy wins.
I did a search of all intra-European flights for tomorrow (12 Feb 2018) and came up with the following:
That’s just for one day. It’s certainly likely that a lot of small routes with small planes don’t fly everyday so I’m probably missing some.
Wikipedia lists a few dozen European operators of Britten-Norman Islanders. Many of them are historical, but a few appear to currently fly scheduled routes with them:
Credit:stackoverflow.com‘