US2847668A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Pilot's indicators for aircraft instrument landing or approach systems
Assignee: National Research Development Corp UK
•
Filing: 1953-07-20
•
Granted: 1958-08-12
•
Expires: 1973-07-20
Abstract
No abstract record available.
Inventors
- 👤 Calvert Edward Spence
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 05:56
CPC Classifications
G; G01; G01C; G01C23/00; B; B64; B64D; B64D45/00; B64D45/04; G01S; G01S1/00; G01S1/02; G01S1/04
Claims Analysis
Total Claims: 0
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1961-08-11 | 1962-02-10 | 1962-08-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1965-08-11 | 1966-02-10 | 1966-08-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1969-08-11 | 1970-02-10 | 1970-08-12 | $7700.00 | Window Closed / Lapsed |