Note 1 - Nature of Operations, Organization and Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands	12 Months Ended
Apr. 30, 2017	Apr. 30, 2016
Duration after Which Invoices Are Considered to Be Doubtful	90 days
Allowance for Doubtful Accounts Receivable	$ 112	$ 81
Duration During Which Inventory If Inactive Taken as Obsolete	5 years
Inventory Valuation Reserves	$ 1,177	1,161
Proceeds from Sale of Flight Equipment		959
Gain (Loss) on Disposition of Property Plant Equipment		732
Period for Payment Due	30 days
Cash, Uninsured Amount	$ 2,312	3,546
Research and Development Expense	1,479	1,838
Kansas Expanded Lottery Act Management Contract Privilege Fee [Member]
Finite-Lived Intangible Assets, Gross	5,500	5,500
Gaming Equipment [Member]
Finite-Lived Intangible Assets, Gross	$ 5,012	4,576
Finite-Lived Intangible Asset, Useful Life	3 years
JET Autopilot Intellectual Property [Member]
Finite-Lived Intangible Assets, Gross	$ 1,417	$ 1,417
Finite-Lived Intangible Asset, Useful Life	15 years
Other Miscellaneous Long-Term Assets [Member]
Finite-Lived Intangible Assets, Gross	$ 1,457
Supplemental Type Certificates [Member]
Finite-Lived Intangible Asset, Useful Life	7 years
Minimum [Member]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life	39 years

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Represents the duration during which inventory if inactive taken as obsolete.

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Period for payment due from invoice date after shipment for revenue recognition of products sold.

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For an unclassified balance sheet, a valuation allowance for receivables due a company that are expected to be uncollectible.

+ References

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-Name Accounting Standards Codification
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-SubTopic 10
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The amount of cash as of the balance sheet date that is not insured by the Federal Deposit Insurance Corporation.

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount of gain (loss) on sale or disposal of property, plant and equipment assets, including oil and gas property and timber property.

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Amount of valuation reserve for inventory.

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Cash received from sales of long-lived depreciable flight assets, including owned aircraft or capital improvements.

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The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use.

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