Flight Number Question

"Bob" wrote in message ...
Had an interesting experience yesterday flying from DEN to ORD. Due to
weather at ORD, we were put into a hold pattern over Kansas City for about
40 minutes. At that time, the captain turned on Channel 9 so we could
listen in. We were United 942 but our call sign to ATC was different,
United 8735 (or something similar). Why would we have a different call
sign
from our flight number?

By ICAO standards, any flight in the 8000 series is considered an "extra" or
"special" flight segment. (Can't find a table online that explains what
different "blocks" of flight numbers are reserved for). UA often uses 8xxx
flight numbers on a domestic segment of a flight that continues
internationally with a change of planes. In your specific case, UA942 is a
772 from DEN-ORD and a 763 ORD-CDG. As someone else posted, if the DEN-ORD
leg is late and they depart the ORD-CDG flight (which you said actually
happened), there will be two UA942 flights in the air simultaneously. To
prevent this from happening, airlines will assign a 8xxx flight number if a
delay seems likely. In UA's case they seem to do it as a matter of
practice. Your recovery leg from Rockfield to ORD was also a "special"
flight and got an 8xxx number.

You will often see 8xxx flight numbers when airlines add a second plane to a
regular flight due to demand (large group, special event, peak travel day,
etc.)

Ken Ishiguro