Note 4 - Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Apr. 30, 2021	Apr. 30, 2020
Long-Term Debt
Notes payable	$ 46,160	$ 5,439
Less: Origination fees	372
Long-term Debt, Total	45,788	5,439
Less: Current maturities	5,972	2,228
Long-term Debt, Excluding Current Maturities, Total	39,816	3,211
Note Collateralized by Real Estate [Member]
Line of Credit, Current
Long-Term Debt
Long-term Debt, Excluding Current Maturities, Total	5	5
Notes Collateralized by Aircraft Security Agreements, Due January 2023 [Member]
Long-Term Debt
Notes payable	1,138	1,706
Note Collateralized by Real Estate Due June 2024 [Member]
Long-Term Debt
Notes payable	202	224
Note Collateralized by BNSC's Assets and Compensation due under State Management Contract Due May 2020 [Member]
Long-Term Debt
Notes payable		104
Note Collateralized by Equipment Due April 2022 [Member]
Long-Term Debt
Notes payable	21	42
Note One Collateralized by Real Estate Due March 2029 [Member]
Long-Term Debt
Notes payable	1,267	1,426
Note Two Collateralized by Real Estate Due March 2029 [Member]
Long-Term Debt
Notes payable	581	654
Notes Collateralized by BHCMC's Assets and Compensation Due under State Management Contract Due December 2027 [Member]
Long-Term Debt
Notes payable	34,417
Notes Collateralized by BHCMC's Assets and Compensation Due under State Management Contract Due December 2025 [Member]
Long-Term Debt
Notes payable	6,533
Paycheck Protection Program CARES Act [Member] \| Aerospace Products [Member]
Long-Term Debt
Notes payable		1,283
Paycheck Protection Program CARES Act [Member] \| Professional Services [Member]
Long-Term Debt
Notes payable	$ 2,001

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount of unamortized debt discount (premium) and debt issuance costs.

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The carrying value as of the balance sheet date of the current portion of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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