Information, information - just tell the pax what's happening
Gate staff have a terribly difficult job managing the SLF in the event of a last minute problem (a late incoming flight, or one that arrives on time but has developed a fault that needs to be rectified). A delayed passenger is, after all, by-and-large an irritated one.
Yet there's an easy way to ease the irritation - just tell people what's going on. And after years of "unspecified delay" announcements, I've had two examples recently, in quick succession, of how easy it could be to do it properly (both, perhaps surprisingly, from FlyBe).
Sitting at Norwich, waiting for my weekly Dash-8 flight to work, we had an announcement from the gate staff that "a fault had developed on the aircraft". I noticed a FlyBe captain sitting in the departure lounge, who immediately picked up his mobile phone; it was clear he was talking to the inbound captain, and when he'd finished his call he explained to those of us in earshot that the problem was with a dodgy radio. A few minutes later the inbound captain called our guy in the departure lounge to say that the techie had visited and had said it'd take maybe 2-3 hours to repair as they didn't have a spare unit to hand they could slot in. No worries - it meant that we could call our various offices and let them know about the delay, and that we could happily grab a coffee and a newspaper in the knowledge that we'd have time to drink/read them. Excellent unofficial information, but all the official announcements we got over the next 2-3 hours was a couple of "The delay will be at least another hour" announcements.
On a different day, again at NWI and bound for EDI, we pushed back and then waited ... and then went right back into the stand. Another fault, and they decided to send us back into to the terminal. This time, though, I had a connection; if the delay was more than a couple of hours, I'd miss the only flight from EDI to my place of work. So I said to the CC: "Any chance we can find out how long the delay is? If it's more than a couple of hours, I'm stuffed so I'll leave and hop on the train to Gatwick instead, and fly from there". The First Officer's reply: "We dunno yet - the engineer's on his way. Tell you what, let me have your mobile number and I'll give you a bell once he's had a look". This I did.
In the queue at the coffee shop a few minutes later, my phone rang: the F/O. "The engineer knows what the problem is. He's going to try something; if it works, we'll be going shortly, if not it'll be four hours". I passed on the news to the rest of the pax (pretty well all of us were getting coffee). Ten minutes later, and halfway down my coffee, the phone rang again. "He's fixed it; we'll be boarding in a few minutes". Yet as soon as I hung up, the announcement came over the PA system: "The engineer is looking into the problem; further information will be given in 45 minutes". Doh! As we boarded I thanked the F/O most profusely for his above-and-beyond service, and the mood among the pax (by this time most of us were chatting amicably to total strangers about how unusual the situation was) was extremely cordial.
The moral is: the information's available, so get it to the passengers and they'll think you're brilliant. A simple connection between flight, tech, ground and gate staff would inevitably reduce passenger irritation - and this huge customer perception boost could be achieved for virtually zero cost.
I spent six years commuting on the train from Norwich to London. I wish I had a pound for every time I heard people musing along the lines of "The delay's a bearable inconvenience, but for &$%^'s sake why can't someone tell us what's going on?". Well, the same applies in airports.