Consolidated Balance Sheets - USD ($) $ in Thousands	Apr. 30, 2019	Apr. 30, 2018
CURRENT ASSETS:
Cash	$ 9,014	$ 7,353
Accounts receivable, net of allowance for doubtful accounts	3,265	3,107
Asset held for sale, net of accumulated depreciation	447
Income tax receivable	27	219
Inventories
Parts and raw materials	7,370	5,858
Work in process	1,441	1,234
Finished goods	74	27
Total inventory, net of allowance	8,885	7,119
Prepaid expenses and other current assets	1,646	978
Total current assets	23,284	18,776
PROPERTY, PLANT AND EQUIPMENT:
Land and building	7,464	5,779
Aircraft	8,467	6,157
Machinery and equipment	4,085	3,922
Office furniture and fixtures	7,477	6,658
Leasehold improvements	4,032	4,032
	31,525	26,548
Accumulated depreciation	(16,714)	(15,725)
Total property, plant and equipment	14,811	10,823
SUPPLEMENTAL TYPE CERTIFICATES (net of accumulated amortization of $6,054 at April 30, 2019 and $5,164 at April 30, 2018)	6,407	6,597
OTHER ASSETS:
Deferred tax asset	295	193
Other assets (net of accumulated amortization of $9,370 at April 30, 2019 and $8,213 at April 30, 2018)	4,105	5,042
Total other assets	4,400	5,235
Total assets	48,902	41,431
CURRENT LIABILITIES:
Promissory notes		2,387
Current maturities of long-term debt	1,899	1,612
Current maturities of capital lease obligation	8
Accounts payable	1,774	2,215
Customer deposits	2,758	1,396
Gaming facility mandated payment	1,280	1,219
Compensation and compensated absences	1,664	1,439
Deferred tax liability, current	236
Other current liabilities	230	162
Total current liabilities	9,849	10,430
Long-term debt, net of current maturities	2,076	1,735
Capital lease obligation, net of current maturities	1,689
Deferred tax liability	944
Total long-term liabilities	4,709	1,735
Total liabilities	14,558	12,165
COMMITMENTS AND CONTINGENCIES
STOCKHOLDERS' EQUITY:
Common stock, par value $.01: authorized 100,000,000 shares issued 71,008,122 shares, and outstanding 68,281,071 shares at April 30, 2019 and issued 66,196,854 shares, and outstanding 64,743,317 shares at April 30, 2018	710	662
Capital contributed in excess of par	14,767	14,231
Treasury stock at cost, 2,727,051 shares at April 30, 2019 and 1,453,537 shares at April 30, 2018	(1,387)	(951)
Retained earnings	13,913	10,060
Total Butler National Corporation's stockholders' equity	28,003	24,002
Noncontrolling interest in BHCMC, LLC	6,341	5,264
Total stockholders' equity	34,344	29,266
Total liabilities and stockholders' equity	48,902	41,431
Preferred Class A [Member]
STOCKHOLDERS' EQUITY:
Preferred stock
Preferred Class B [Member]
STOCKHOLDERS' EQUITY:
Preferred stock