Condensed Consolidated Balance Sheets (Current Period Unaudited) - USD ($) $ in Thousands	Jul. 31, 2020	Apr. 30, 2020
CURRENT ASSETS:
Cash	$ 17,610	$ 16,793
Accounts receivable, net of allowance for doubtful accounts	3,830	2,784
Inventories
Parts and raw materials	7,062	6,892
Work in process	2,925	1,661
Finished goods	53	62
Total inventory, net of allowance	10,040	8,615
Prepaid expenses and other current assets	1,862	1,620
Total current assets	33,342	29,812
PROPERTY, PLANT AND EQUIPMENT:
Lease right-to-use assets	44,349	44,349
Land and building	5,805	5,805
Aircraft	8,740	8,511
Machinery and equipment	4,195	4,093
Office furniture and fixtures	9,544	8,533
Leasehold improvements	4,032	4,032
Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, before Accumulated Depreciation and Amortization	76,665	75,323
Accumulated depreciation	(21,754)	(20,577)
Total property, plant and equipment	54,911	54,746
SUPPLEMENTAL TYPE CERTIFICATES (net of accumulated amortization of $7,275 at July 31, 2020 and $7,029 at April 30, 2020)	6,872	6,483
OTHER ASSETS:
Other assets (net of accumulated amortization of $10,336 at July 31, 2020 and $10,153 at April 30, 2020)	3,363	3,546
Total other assets	3,363	3,546
Total assets	98,488	94,587
CURRENT LIABILITIES:
Current maturities of long-term debt	2,852	2,228
Current maturities of lease liability	1,200	1,163
Accounts payable	1,356	962
Customer deposits	6,656	1,994
Gaming facility mandated payment	1,246	1,338
Compensation and compensated absences	1,756	2,571
Income taxes payable	200	206
Other current liabilities	314	274
Total current liabilities	15,580	10,736
LONG-TERM LIABILITIES
Long-term debt, net of current maturities	2,993	3,211
Lease liability, net of current maturities	41,898	42,211
Deferred tax liability, net	625	625
Total long-term liabilities	45,516	46,047
Total liabilities	61,096	56,783
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Common stock, par value $.01: authorized 100,000,000 shares issued 77,719,677 shares, and outstanding 74,186,262 shares at July 31, 2020 and issued 77,719,677 shares, and outstanding 74,398,262 shares at April 30, 2020	777	777
Capital contributed in excess of par	15,750	15,600
Treasury stock at cost, 3,533,415 shares at July 31, 2020 and 3,321,415 shares at April 30, 2020	(1,821)	(1,713)
Retained earnings	18,132	18,147
Total Butler National Corporation's stockholders' equity	32,838	32,811
Noncontrolling interest in BHCMC, LLC	4,554	4,993
Total stockholders' equity	37,392	37,804
Total liabilities and stockholders' equity	98,488	94,587
Preferred Class A [Member]
STOCKHOLDERS' EQUITY:
Preferred stock
Preferred Class B [Member]
STOCKHOLDERS' EQUITY:
Preferred stock