United 357 Is a flight from BWI to DFW via ORD. I’ll be taking this flight next week, thus my interest in this one. The route for this flight number just changed a couple of days ago - it used to be Kansas City to Denver.

So anyway, the BWI to ORD leg is like 3.5 hours late today - UAL’s Web site says due to late arriving aircraft. Alright… stuff happens… whatever. So FlightAware has it arriving ORD at 7:11

Now, as I post this, FlightAware shows no record of the ORD to DFW run, but UAL’s site shows it as having left ORD on time at 4:49 and arriving DFW at 7:27

So how can a flight takeoff 3.5 hours late for the first leg and arrive on time for the second one? The only thing I can think of would be that they rolled out another plane at ORD and sent the ORD to DFW pax on their way (on time) and made other arrangements for the BWI to DFW pax :question:
This would create two UAL357 flights which would conflict in FlightAware’s tracking database and cause the second one to be rejected?

Anybody have any thoughts, ideas or theories?

Sure glad my trip is next week and not today, and hope that they get things straightened out next week!


It almost looks like the ORD-DFW leg was operated by UAL8133.


FlightAware’s history shows different aircraft types, as well as different origin and destination cities

United’s timetable shows 8133 as a daily flight from Cleveland to Toronto.

Their Web site’s flight status report for 8133 shows:
Flight: 8133 Operated as AIR CANADA JAZZ Flight AC 7905

FlightAware shows daily flights for JZA7905


I saw that two, but my guess would be that that’s just the codeshare flight number, and not actually used by the flight.


A flight number in an airline’s timetable is not necessarily the flight number that an airline uses for the actual flight.

As an example, an airline could have the following flights:

However, the airline only has 1 flight from ATL to LHR (flight 1, for example). The other flights are shown as through flights to give them an advantage in the reservations system.


I have noticed the same thing. Perhaps reversing the situation will make more sense. Think of how many times you flew from LGA-ORD-SFO for example, and you booked the flight as LGA-ORD is flight 123 and ORD to SFO is flight 234, yet its the same plane. Its a different flight NUMBER, but the same plane. Thus, you would have to change planes to fly the same flight number.

There seem to be two factors in numbering flights. First, the airlines came up with city pairs and gave it a number (rather random, the lower the number the more proud they are that they fly that route). Then, they rearrange a few here and there so that similar sounding callsigns aren’t out of control.

With that said, very often, there is only one segment to each flight number, or the same plane continues on if the demand is similar for both.



When I search for flights on the Internet, I notice each way of a trip will usually have two (or more) flights and each flight says non-stop - which means there’s a connection in between.

In the case of UAL357 BWI to DFW, it is listed as one flight with one stop, which indicates to me that it’s the same plane going from BWI to ORD and then continuing on to DFW. FlightAware’s tracking history for the flight shows two flights each day (BWI to ORD and ORD to DFW) - except for Saturday - the day in question.

I’m not questioning if this flight is one leg, or two legs - one plane or two planes.

What I’m really questioning here, is if it makes sense that if a flight of two legs is more than three hours late, would they get another plane going on time for the second leg? - And what would become of the BWI pax who were continuing on to DFW.

It appears as if they did get the ORD to DFW flight out on time with UAL8133 (probably used that flight number arbitrarily being a flight number not in use for that particular day). But then again it is used in their timetable as a daily codesharing flight. I find that confusingly interesting. I’ve never had any real experience with a codesharing flight. Just trying to get a grasp on how United handled this particular delay.

I think it’s awesome that they didn’t make the ORD to DFW pax wait, but that would be of little consolation to me if I was on the BWI to DFW flight as I’m scheduled to be this Saturday!


In the case of UAL357 BWI to DFW, it is listed as one flight with one stop, which indicates to me that it’s the same plane going from BWI to ORD and then continuing on to DFW.

This is not necessarily true. A flight can have one flight number and have a change of gauge (i.e. aircraft) enroute. While it doesn’t happen too often on domestic flights, it does happen quite often international flights. For example, a SEA-JFK-LHR flight may have a 767 for the SEA-JFK leg and a 777 for the JFK-LHR leg.

There is a discussion elsewhere on this forum regarding the differences between direct, nonstop, and through flights. Please use the search feature to find it.


It is a domestic flight, and if you check the links I’ve provided,
you’d see that the same aircraft type is used for both legs of each day. The aircraft type varies from day to day, but it remains the same for both legs each day.


My experience is that the airlines often do “stub” the second leg of a flight if the first leg is running many hours behind schedule. This is done by rolling out a spare airplane and having it depart from the middle city on time, and then when the late airplane arrives from the first leg, it becomes the spare. This especially works well if there was supposed to be a crew change at the middle airport. Then you get the new crew running on time, so that the rest of their sequence of flights is also on schedule. Keeping an airline running on schedule is quite a chess game - computers are used to help make those kinds of decisions. Usually the “stub” flight (the second leg) will have a different flight number, so that ATC will not have two airplanes with the same number in the system at the same time. At American the stub flight will have a letter after the flight number, such as flight 847P (eight forty seven papa on the radio). As for the through passengers - there are usually one or none! Passengers rarely get on a plane in the east, go through a hub, and stay on the same plane! The news media (after a crash) is always so concerned about where the airplane originated, when that fact is almost irrelevant. Very very few passengers stay on board a flight passing through a hub.


I didn’t say it was ALWAYS true, just not necessarily true. I know that the vast majority of direct flights in the USA have the same aircraft for both legs.