On Jan 4, 3:37*pm, (John Clear) wrote:

Is this United's infamous 'change of gauge' 'direct' flight trick?
According to FlightAware, UAL893L is a 757 flying KJFK-KSFO and
UAL893 is a 777 flying KSFO-RKSI (Seoul, Korea).

Not the old "Change of gauge direct flight trick" again. Whats that ?

Does the letter have any special meaning beyond that it appears to
be another flight using the same flight number but a different
aircraft?
Here's the story, when an airline has a through flight (Through a hub
airport), and the inbound flight is running late and the outbound
flight is a different AC (Or another plane and crew can be rerouted),
they will send the outbound flight on time but with a different call
sign. You cannot have two flights in the air at the same time with
that flight number.
FB