I’m curious to find out what happened with DL 91 on the PDX-NRT flight tonight. They got halfway to NRT and then turned around and went back to PDX. Surely if it were an emergency they would have gone to ANC or something, and it seems that the flight would have just continued to NRT at that point rather than going all the way back to PDX were it something non-critical.
They stayed at altitude, actually climbing from FL 300 to FL 310 so pressurization or engine failure was not the issue. Although they do descend to FL 250 only a few minutes later.
On more examination I’m a little suspicious, there is almost an hour between the last westbound position report and the first eastbound position report.
Nothing in the Portland news online.
There is a good chance it could have been a maintenance related issue, the crew called into dispatch and Maint Control and or dispatch had them to return rather than deal with the issue. Could have been an indication fault such as Flaps, Gear, or other items that they would have rather repaired it at there own maint base.