SYD securities are stapled. Roughly speaking, for your share you get one share in an entity which is the airport and another share in an entity which lends to the airport. Debt is less of an issue when its owed to yourself.
You will notice that SYD doesn't really pay tax. This is because they use the debt to eliminate them, making their earnings appear artificially low. Their earnings do not reflect the money they are making and largely can be ignored. Look at their cash flow instead, a pretty dependable 45c per share or so for years now. The dividends are paid from this.
SYD Price at posting:
$6.60 Sentiment: Hold Disclosure: Not Held