COMMITMENTS AND CONTINGENCIES Aircraft orders and options (Details) - aircraft	12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Mar. 31, 2017
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircrafts purchased without orders	1	0	1
Commitments
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft - beginning balance	27	32	36
Number of aircraft delivered	0	(5)	(9)
Number of aircraft ordered	0	0	5
Number of Aircraft Cancelled Order	(1)	0	0
Number of expired options	0	0	0
Number of aircraft - ending balance	26	27	32
Options
Unrecorded Unconditional Purchase Obligation [Line Items]
Number of aircraft - beginning balance	4	4	14
Number of aircraft delivered	0	0	0
Number of aircraft ordered	0	0	0
Number of Aircraft Cancelled Order	0	0	0
Number of expired options	(4)	0	(10)
Number of aircraft - ending balance	0	4	4