Likely a Slat or Flap Locked abnormal - straightforward QRH procedures, well practised in the sim. There are a few considerations but the most significant one is in the QRH notes for fuel consumption with any slat-flap extension, and will almost certainly be the reason for the turn-back.
Depending upon the configuration at the time of failure, the approach speed (Vls) would likely either have been Vref + 10kts (For takeoff - Slats extended to Config 1, Flaps at Config 2) or Vref + 25. Both runways are more than capable of handling the slightly longer landing run required. It was an abnormal, not a full emergency as initially described by local media.
Re the media....
I see some reluctance to criticize the media but the talking heads were bandying around phrases like, "emergency landing with 290 people on board" when nobody really knew what the issue was. "Selling" the story seemed to justify the hype; - the landing was just in time for the local evening news.
The turnback and landing was much ado about nothing. If the media wants to avoid the criticisms offered up here, these stories have to be handled more maturely and with integrity - which means inform people without sensationalization. I used to accept calls from media people (and was asked about this one), to discuss these kinds of events but more than once I was either trapped into my words and taken out of context or what I said was sensationalized even though I said at the time it was not what I meant. Almost without exception, one simply cannot have a technical discussion with the media and expect it to used as intended. I know Larry Pynn of the Vancouver Sun and was there when he was awarded the Flight Safety Foundation's Cecil A. Brownlow Award
for Publication in 2006 so I know good aviation reporting can be done. Byron Acohido, (Seattle Post
Intelligencer - (Pulitzer Prize B737 series) is another. Too often when it comes to aviation accidents however, reporters have short deadlines and need it snappy, sexy, short and preferably with a targeting sound-bite. That said, the relationship is symbiotic with the reading public which enjoy a good vicarious daily scare.
If one wishes to control such interviews, one learns very quickly how to get the message across and still do it accurately but experience has taught that this is rarely the full agenda. It is a sales and entertainment business, not an information/education business.
Here's the QRH Note:
As a guideline, determine the fuel consumption in clean configuration at same altitude without airspeed limitation (e.g. from ALTERNATE FLIGHT PLANNING tables) and multiply this result by 1.4 (SLATS EXTENDED) or 2 (FLAPS EXTENDED) or 2.3 (SLATS and FLAPS EXTENDED) to give the fuel consumption required to reach the destination in the current