| Tail Number / N-Number | N121SK |
| Manufacturer | MOONEY |
| Model | M20J |
| Year Built | 1979 |
| Manufacturer's Serial Number | 24-0901 |
| Aircraft Type | Fixed wing single engine |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 4 seats |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | LYCOMING |
| Engine Model | I0360 SER A&C |
| Engine Type | Reciprocating |
| Number of Engines | 1 engine |
| Horsepower | 200 hp (149 kW) |
| Average Cruising Speed | 126 miles per hour |
| Type of Registrant | Co-Ownership |
| Owner Name | REGE ROBERT E |
| Other Names |
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| Street | PO BOX 566 |
| City | CLOVERDALE |
| State | CA |
| Zip Code | 95425-0566 |
| Region | Western-Pacific |
| County | Sonoma County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Standard |
| Airworthiness Date | 1979-10-30 |
| Certificate Issue Date | 2014-11-18 |
| Last Action Date | 2020-06-11 |
| Expiration Date | 2027-11-30 |
| Status | Valid Registration |
| Mode S Code | 50054403 |
| Mode S Code Hex | A05903 |