Originally Posted by GagaPilot

Just thought I would share an interesting IDB I witnessed last night. Mostly just posting as an anecdote for other FT nerds, but also as there have been several discussions lately about how much DL IDBs/VDBs.

I was on DL2169 ATL-ECP, the last flight of the night. Before boarding the GA announced they were oversold by 9 and needed volunteers to take a morning flight. 9 seemed high to me to oversell the last flight of the night, but I'm assuming the number got that high because of displaced passengers from earlier flights. By the time I boarded with F they were down to needing only 3. I boarded, and took my seat in 3A.

As boarding appeared to finish no one had sat in 3B next to me. The GA came onboard and said to the FA: "I'm showing 1 open up front and 3 in the back." The FA checked his mobile device and confirmed that's what he saw as well and went to the back to confirm. He came back confirming it, and the GA said "Great, as we never got enough volunteers and still need 3 seats. I'll send them down." As he goes to leave, another FA comes up saying there's a problem with a row of 3 seats. After she went up to the flight deck the CA went back to look at the seats. He quickly came back up front and called MX. Within a few minutes MX was there and whatever the issue was could not be fixed quickly, so they had to defer that row. The 3 passengers in that row then filled the 3 remaining seats in the back.

The GA came back down and told the FA they had IDB'd the other 3 remaining passengers for maintenance reasons and would be good to go shortly. The FA pointed out empty 3B next to me, to which the GA said he had offered to the 3 passengers, but they had declined as they didn't want to split up from traveling together. The FA then asked if they were going to UG someone into the seat, to which the GA said "No, I'm just gonna take the first non-rev on the list, we gotta get this flight out." (Kudos to the FA for trying to get the seat filled with revenue pax, either the IDB ones or an UG).

A few minutes later a non-rev comes on board and sits next to me. The FA even offered her a quick PDB. The CA comes out, looks at 3B, and goes back up the jet bridge. A few minutes later he and the GA came back on board. The CA returned to the flight deck while the GA came down and said to the passenger in 3B "Ms. XXXXXX I am so sorry, but the CA pointed out a policy I had overlooked. Since we had to involuntarily deny boarding to 3 revenue passengers for those broken seats, we can't take any non-revs tonight. I am so sorry. If you are qualified to sit in a jumpseat we can take you, but otherwise I am going to have to ask you to deplane." The non-rev quickly gathered her things and stepped off (taking the PDB with her I might add, haha).

And with that the door closed and 3B next to me was empty for the short flight. I did feel bad for the non-rev as I'm an airline pilot myself, but never non-rev because I don't like the stress of knowing whether or not I will get a seat.

So ultimately the IDB was for mechanical reasons, not for lack of volunteers. But it was still an interesting process to watch and observe.