"sudden passing" is correct and usable in written English.
It is used to refer to the unexpected death of a person. For example, "We were all saddened by the news of her sudden passing."
His sudden passing diminishes us all.
Our hearts are broken by their sudden passing.
WERTHEIMER--Florrie. We are deeply shocked and saddened by her sudden passing.
In Kingston today, many residents expressed shock and sadness over the mayor's sudden passing.
With great sadness we announce his sudden passing on November 17th, 2006.
It is with deep sadness that we mourn your sudden passing.
Andy gave us the extra light we need to face his sudden passing.
Mayall's wife, Barbara Robbin, told reporters that she didn't know the reason for her husband's sudden passing.
"Although not entirely unexpected at the age of 19, it comes right on the heels of Sunkist's sudden passing just a couple of weeks ago".
Comics Stealing the Show: A Week in Comedy Many of his clients spoke of their shock and sadness at his sudden passing.
Secretary for the Fire Brigades Union (FBU) Greater Manchester Gary Keary said: "The Fire Brigades Union are deeply saddened to hear about Lee's sudden passing".
