The United Airlines documents we have don’t show all the passengers we expected. Why? We don’t know, but previous air disasters have shown that compiling a list of passengers on a flight isn’t always straightforward. Here’s an interview with TWA president Jeffrey Erickson in 1996, where he tries to explain the difficulties the airline faced in producing an accurate passenger list for TWA 800:

MR. ERICKSON: ...it’s a very complicated process. You have passengers coming from throughout the system to get on this airplane. The, the lists are mostly complete. Unfortunately, they weren’t complete to the point of view that we were satisfied with the accuracy, so I--I talked to a number of the leaders on the Hill, and I support that sort of legislation.

JIM LEHRER: Why was the--why is the--just go through the mechanics of this for us, Mr. Erickson, so we can understand--why is the passenger manifest, the official passenger manifest of Flight 800 or any flight of TWA or any other airline not accurate when it--when the flight--when the plane takes off?

MR. ERICKSON: Well, a number of things--things happen. You may have people that are taken off the airplane and moved to other flights. That, indeed, happened in this case. There are a number of--

JIM LEHRER: In other words--excuse me--on 800 there were names on the official passenger list who were not, in fact, on that plane, is that right?

MR. ERICKSON: There were names on the, on the original manifest that did not, indeed, go on the flight. There were also a number of employees that use ticket lists, travel to get on the flight, so what we really had to do was to assemble from a variety of lists, from the manifest, from the baggage list, from the Immigration's list, we check all these. If they were all the same, there would have been no problem, but they, indeed, were different, and we wanted to desperately make sure that people weren’t getting informed, that they had lost someone that indeed wasn’t on the flight.

JIM LEHRER: How did you determine, for instance, if somebody’s name turned up on the master list, how did you determine that that person wasn’t, in fact, on that airplane when there were no bodies to look at, particularly the first twenty-four hours, forty-eight hours, et cetera?

MR. ERICKSON: Well, of course, we match it against the, the baggage list. The baggage list is very accurate but not everybody checks a bag, so not everybody is on that list, but, but we go through a variety of techniques. We’ll check the boarding passes from all the different stations that people may have started to, to connect to the, to this flight, and assemble it all through the course of the night to make sure that it’s accurate, it’s been submitted to the NTSB, and then we start notification which began at about 8 AM.

JIM LEHRER: That’s 8 AM the next day.

MR. ERICKSON: Correct.

JIM LEHRER: Were there cases where people flew under different names?

MR. ERICKSON: There were several cases where, where people either through a divorce or separation situation were under different names. That confused the issue a little bit. It’s a complex--it’s a complex situation that we worked through as quickly as we could. We’d like to see it improve.
http://www.pbs.org/newshour/bb/transportation/july96/erickson_twa_7-24.html