Note 4 - Debt - Schedule of Debt (Details) (Parentheticals) - USD ($)	12 Months Ended
Apr. 30, 2021	Apr. 30, 2020
Notes Collateralized by Aircraft Security Agreements, Due January 2023 [Member]
Interest rate	6.25%	6.25%
Maturity date	Jan. 31, 2023	Jan. 31, 2023
Note Collateralized by Real Estate Due June 2024 [Member]
Interest rate	6.25%	6.25%
Maturity date	Jun. 30, 2024	Jun. 30, 2024
Note Collateralized by Equipment Due April 2022 [Member]
Interest rate	4.50%	4.50%
Maturity date	Apr. 30, 2022	Apr. 30, 2022
Note One Collateralized by Real Estate Due March 2029 [Member]
Maturity date	Mar. 31, 2029	Mar. 31, 2019
Note One Collateralized by Real Estate Due March 2029 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Basis spread	1.75%	1.75%
Note Two Collateralized by Real Estate Due March 2029 [Member]
Maturity date	Mar. 31, 2029	Mar. 31, 2029
Note Two Collateralized by Real Estate Due March 2029 [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Basis spread	1.75%	1.75%
Note Collateralized by Real Estate [Member]
Borrowing capacity	$ 2,000	$ 2,000
Basis spread	3.65%	3.65%
Note Collateralized by BNSC's Assets and Compensation due under State Management Contract Due May 2020 [Member]
Interest rate	4.89%	4.89%
Maturity date	May 01, 2020	May 01, 2020
Notes Collateralized by BHCMC's Assets and Compensation Due under State Management Contract Due December 2027 [Member]
Interest rate	5.32%
Maturity date	Dec. 31, 2027
Notes Collateralized by BHCMC's Assets and Compensation Due under State Management Contract Due December 2025 [Member]
Interest rate	5.83%
Maturity date	Dec. 31, 2025
Paycheck Protection Program CARES Act [Member] \| Professional Services [Member]
Interest rate	1.00%

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
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- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
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Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

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