Yes, as follows.
Singapore airlines has changed its depreciation policy from 10 years to 15 years, therefore reducing its depreciation bill by 134m SGD. It also transferred its freighter fleet to SQ Cargo (100% owned) therefore was able to recognise a 267m SGD revaluation surplus on those aircraft.
UA took a big charge to reduce value of B744. 20m USD an aircraft IIRC
AA wrote off the value of the F100 fleet
TG bought a 12 year old B744 off lease for 21m USD, gives a good idea of the sort of market value these days
B747-200 are now going for 2m USD each, which is basically the value of the engine life until the next overhaul.
Ceilidh, off balance sheet depends on the nature of the lease. An operating lease just goes through the P&L account. Finance leases in most jurisdictions must be capitalised and put on the balance sheet. Sort of like the difference between renting a house (operating lease) and having a mortgage (finance lease)