There would seem to be a problem with that. When elected, the chairman must sign a declaration of acceptance of office at the same meeting. That would seem impossible if they are absent, and without the signed declaration, the election is invalid.
CORRECTION: The declaration of office must be signed before the person can officiate, and once elected they must officiate if present. Hence the declaration is usually signed immediately on election. However, I can confirm that it is possible to elect a person as chair in their absence. I believe they need to have stated in advance that they are prepared to accept nomination.