It Makes Sense Now

Let me state right up front that I’m guessing. I don’t know this for a fact. It just fits.

I bumped into a controller friend the other day and he told me a somewhat amusing story about a recent event involving flight plans. A particular vendor that has a flight planning service suddenly stopped putting the equipment suffix in flight plans.

For those that don’t know, there are various types of navigational equipment on aircraft. (Those that do know this stuff feel free to skip ahead.) Each different type of equipment has its own suffix. The equipment suffix is tacked onto the type aircraft. So when a controller would ask another to “say type aircraft”, the answer always came back as “Cessna three ten slant Alpha”. That would be written on the flight progress strips as “C310/A”. The “slant Alpha” meant that the aircraft was equipped with VOR navigation equipment with DME and his transponder had Mode C capability. Here are some other examples.

B757/F -- A Boeing 757 equipped with a Flight Management System (FMS) that depends on DME for position information.

LR35/I -- A Lear 35 capable of Area Navigation (RNAV) with either LORAN, VOR/DME or an Inertial Navigational System plus Mode C.

C210/G -- a Cessna 210 with Advanced RNAV capability using GPS.

(You can view the whole table here.)

Anyway, for some reason, this vendor suddenly stopped putting an equipment suffix in all the flight plans they submitted to the FAA. As you may have picked up in the discussion, the equipment suffix also tells us what type transponder the aircraft has. No equipment suffix, no transponder. If you don’t have a transponder, the computer doesn’t assign a beacon code.

Cessna one two three four is cleared to Peachtree-Dekalb via depart Hickory direct Sugarloaf Victor two twenty two LOGEN direct, climb and maintain six thousand, squawk....uh....standby. Ask this guy who he filed his flight plan with and find out what his equipment suffix is.

As I said, the problem was finally tracked down to a vendor. It was reported to me that no one in the FAA (even in Washington) could find a telephone number for the vendor to inform them of the error. All anyone could find was an email address. I have to question that too, in that I had a manager call up a DUATS vendor (about a different problem, long ago) while I was standing there listening. Of course, the vendor told us he didn’t have to talk to us and if we had a problem, we needed to call FAA headquarters and have them call. Maybe vendors don’t need to have a telephone number.

Pretty soon, getting any support for air traffic control will be like calling tech support for your computer. “It’s a software problem, call them.” "It’s a modem problem, call them.” “It’s your ISP’s problem, call them.”

Oh well, it’s an amusing story and one I had decided to pass up until I read this today from AINonline:

” The new Host systems will automatically assign preferential routes based on the equipment capability contained in an ICAO-filed flight plan, according to the FAA. The first operational use of ERAM, which will make the NAS system ICAO compatible, is scheduled for October at the Salt Lake City ARTCC. “

(Emphasis added)

Like I said, it’s just a guess but I’m betting the two are connected. A vendor’s software suddenly messes up the equipment suffix and a few days later I find that ERAM will assign routes based on the equipment suffix. I could be wrong but it makes sense to me.

In any event, I hope you’re feeling a little uneasy about how software problems make it through the system all the way to the controller. I was reading another variation of this theme today where pilots using NEXRAD weather radar are finally understanding just how much computer programmers working for vendors are massaging the data the pilot depends on to keep them out of thunderstorms. Public information, private vendors, public safety and computer programmers. I’m betting you’ll see more and more of these issues.

Don Brown
June 3, 2008