Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Jul. 31, 2016	Jul. 31, 2015
Operating activities:
Net loss	$ (835,792)	$ (46,642)
Adjustments to reconcile net loss to cash flows provided by (used in) operating activities:
Depreciation	35,698	40,281
Loss on disposal of assets	1,125	987
Earnings from equity accounted investees less dividends received	344	(793)
Deferred income taxes	1,815	138
Non-cash stock-based compensation expense	689	1,199
Net gain on debt extinguishment	0	(14,687)
Amortization of long-term debt and lease deferred financing costs	1,142	2,469
Unrealized net gain on derivative financial instruments	(8,786)	(3,442)
Non-cash defined benefit pension expense (income)	890	(173)
Defined benefit contributions and benefits paid	(6,878)	(6,777)
Unrealized loss on foreign currency exchange translation	18,516	10,605
Reorganization items, net, non-cash (note 9)	780,510	0
Other	(4,500)	(3,580)
Change in cash resulting from changes in operating assets and liabilities:
Receivables, net of allowance	8,176	30,726
Income taxes receivable and payable	(11,467)	93
Inventories	(1,399)	1,818
Prepaid expenses	5,494	2,715
Payables and accruals	73,690	5,929
Deferred revenue	393	170
Other assets and liabilities	(11,916)	4,203
Cash provided by operating activities	47,744	25,239
Financing activities:
Sold interest in accounts receivable, net of collections	(21,620)	10,602
Debt proceeds	0	150,000
Debt and capital lease repayments	(549)	(95,868)
Repurchases of senior unsecured notes	0	(18,818)
Increase in deferred financing costs	0	(2,179)
Cash provided by (used in) financing activities	(22,169)	43,737
Investing activities:
Property and equipment additions	(11,282)	(80,095)
Proceeds from disposal of property and equipment	1,844	27,723
Helicopter deposits net of lease inception refunds	0	(24,360)
Restricted cash	9,056	(16,638)
Cash used in investing activities	(382)	(93,370)
Effect of exchange rate changes on cash and cash equivalents	(3,303)	(7,793)
Change in cash and cash equivalents during the period	21,890	(32,187)
Cash and cash equivalents, beginning of period	266,130	134,297
Cash and cash equivalents, end of period	288,020	102,110
Supplemental cash flow information:
Non-cash settlement of obligations by letters of credit	$ 39,416	$ 0