A slightly different twist to the same thread:
Some airlines appear to have their private superstitions. For example, around 25 years ago, one of Dan-Air's Boeing 727s flew into a mountain on Tenerife; sadly, all souls on board were lost. The particular aircraft was G-BDAN, which, for obvious reasons, the airline had specially registered with those letters.
Years later, BAe leased a BAe 146 to Dan-Air, and, thinking they were paying the airline a compliment, went to the trouble of re-registering the aircraft G-ODAN. Dan-Air coughed politely, then swiftly re-re-registered it. It seems they (or was it the crews?) were squeamish about having another Alpha November in the fleet....especially a Delta Alpha November.
I once heard from a retired BOAC/BA captain why the airline's VC10 registration sequence (G-ARVA to G-ARVM) conspicuously missed out "G-ARVD
". The official reason was that "VD" was unseemly, since it stood for "Venereal Disease". The truth was that a previous Victor Delta--G-AOVD
, a Britannia 312--had crashed on a post-maintenance check flight with the loss of all the crew, leaving the call-sign letters with "unhappy connotations." I'm inclined to believe the story, because my contact had been with the airline for decades and had flown both the Britannia and the VC10.
Turning the trouble-prone aircraft idea on its head: I recall correspondance in "Flight" magazine some time in the 1960s discussing a particular DC-4 (perhaps a C-54) that had been in service with British United Airways. It seems it flew rather better and with fewer problems than its peers. Its registration happened to be G-APID, so naturally its crews knew it as "Rapid Gapid."