These used to exist (and still do on some flights). I flew on Singapore Airlines from LAX to SIN when they still had their Airbus A340-500 flying nonstop in abo

These used to exist (and still do on some flights). I flew on Singapore Airlines from LAX to SIN when they still had their Airbus A340-500 flying nonstop in about 18 hours between Singapore and Newark or Los Angeles. The whole plane was just 100 seats, business, lie-flat only. Frankly with the odd wide seating they have, you could have easily put 140-150 in there.