Business Segments: (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Sep. 30, 2012 item	Sep. 30, 2011	Sep. 30, 2010
Business Segments:
Number of Operating Segments	1
Geographic Data
Net sales from outside the United States	$ 4.4	$ 4.0	$ 2.8
FPDS
Business Segments
Sales percentage	87.00%	79.00%	68.00%
Air data systems and components
Business Segments
Sales percentage	13.00%	21.00%	32.00%
EMD services
Business Segments
Sales percentage	26.00%	2.00%	7.00%

Revenues from external customers attributed to all foreign countries in total from which the entity derives revenues.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 280

-SubTopic 10

-Section 50

-Paragraph 41

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6534315&loc=d3e9038-108599

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 38

-Subparagraph a(2)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Name:	us-gaap_EntityWideDisclosureOnGeographicAreasRevenueFromExternalCustomersAttributedToForeignCountries
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration