Identifier and "flight check" question

Forgot to post this last week – I was on UA892 from SFO-DEN, and due to runway construction on 1L at SFO, we trudged out to 28R in the middle of a long line of departures. For some reason 1R was not in use, even though there was no weather and wind was calm. (I take that flight often, and we practically always depart on 1R). Anyway, a couple of questions from listening to ATC on Ch. 9:

(1) An arriving aircraft used the call sign “American 539 Quebec”. I hadn’t heard that suffix before, only “Heavy” and “Lifeguard”, maybe a couple of others. What’s “-Q”?

(2) Everything stopped at one point when the tower said, “uh… looks like we’ve got a flight check and they’ve turned off our departures. Hopefully just a few minutes here.” There were a couple of audible groans on the channel and one guy quipped “hey, can’t you do that at 2 AM?” All departures were held up for about 5 or 6 minutes. So, uh, just what is a “flight check”, and why would it cause departures to be held up?

The Q is when the same flight number is being used by a different aircraft, ie flight 539 starts in Boston, with a stop in St. Louis and continues on to San Fran, but the flight is delayed out of Boston so dispatch puts another aircraft on the segment from STL to SFO, since they would then have two flight 539’s airborne at the same time they use a letter to denote one of the flights.

Flight check is the FAA testing the navigation instruments, typically this is a King Air sized aircraft and they check the accuracy of VOR’s, ILS’s, NDB’s, LOC’s and Glide Slopes and there are probably others I am not aware of that they are checking.

Hope this helps.


Thanks for the quick reply!

Hadn’t heard of a suffix for “stub” flights – United (which I’m usually on) usually prepends an 8 (occasionally a 9) such that a continuation stub of UAL867 becomes UAL8867. Interesting. Is the suffix American only?

It varies from operator to operator.

Depending on what component of the airport the Flight Check aircraft was checking, they sometimes need to fly the entire length of the runway to check the navigational aid. The controllers were probably willing to give up the six minutes and the delays involved because they were trying to get a piece of the airport back up and running. In the long run, those few minutes probably helped them out the rest of the day.

Interesting. I wonder if that’s why 1R/19L was not in use that morning. It is not normally used for arrivals (except as 19L in bad weather), but it’s used practically every morning (as 1R) for departures, even more so since 1L was out of service for repaving.