| Tail Number / N-Number | N21840 |
| Manufacturer | CESSNA |
| Model | 172M |
| Year Built | 1974 |
| Manufacturer's Serial Number | 17264031 |
| 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 | 0-320 SERIES |
| Engine Type | Reciprocating |
| Number of Engines | 1 engine |
| Horsepower | 180 hp (134 kW) |
| Average Cruising Speed | 108 miles per hour |
| Type of Registrant | Individual |
| Owner Name | ERICKSON ARNOLD F |
| Street | 2415 AIRPORT RD |
| City | GILLETTE |
| State | WY |
| Zip Code | 82716-8109 |
| Region | Northwest Mountain |
| County | Campbell County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Standard |
| Airworthiness Date | 1974-10-04 |
| Certificate Issue Date | 2010-03-01 |
| Last Action Date | 2022-11-17 |
| Expiration Date | 2030-04-30 |
| Status | Valid Registration |
| Mode S Code | 50355067 |
| Mode S Code Hex | A1DA37 |