Note 2 - Debt - Schedule of Debt (Details) - USD ($) $ in Thousands	Apr. 30, 2020	Apr. 30, 2019
Long-Term Debt
Notes payable	$ 5,439	$ 3,975
Less: Current maturities	2,228	1,899
Notes payable	3,211	2,076
Note Collateralized by Real Estate [Member]
Line of Credit, Current
Notes Collateralized by Aircraft Security Agreements, Due January 2020 [Member]
Long-Term Debt
Notes payable		119
Notes Collateralized by Aircraft Security Agreements [Member]
Long-Term Debt
Notes payable	1,706
Notes Collateralized by Aircraft Security Agreements, Due January 2023 [Member]
Long-Term Debt
Notes payable		2,239
Note Collateralized by Real Estate Due June 2024 [Member]
Long-Term Debt
Notes payable	224	241
Note Collateralized by BNSC's Assets and Compensation due under State Management Contract Due May 2020 [Member]
Long-Term Debt
Notes payable	104	1,313
Note Collateralized by Equipment Due April 2022 [Member]
Long-Term Debt
Notes payable	42	63
Note One Collateralized by Real Estate Due March 2029 [Member]
Long-Term Debt
Notes payable	1,426
Note Two Collateralized by Real Estate Due March 2029 [Member]
Long-Term Debt
Notes payable	654
Paycheck Protection Program Loan [Member] \| Aerospace Products [Member]
Long-Term Debt
Notes payable	$ 1,283

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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