| Tail Number / N-Number | N421EF |
| Manufacturer | ALEXANDER SCHLEICHER GMBH & CO |
| Model | ASK 21 |
| Year Built | 2013 |
| Manufacturer's Serial Number | 21905 |
| Aircraft Type | Glider |
| Category | Land |
| Builder Certification | Not Type Certificated |
| Number of Seats | 2 seats |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | NONE |
| Engine Model | NONE |
| Number of Engines | 0 engines |
| Type of Registrant | Corporation |
| Owner Name | SOARING SOCIETY OF BOULDER |
| Street | PO BOX 17577 |
| City | BOULDER |
| State | CO |
| Zip Code | 80308-0577 |
| Region | Northwest Mountain |
| County | Boulder County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Standard |
| Airworthiness Date | 2013-08-29 |
| Certificate Issue Date | 2014-10-23 |
| Last Action Date | 2020-05-20 |
| Expiration Date | 2027-10-31 |
| Status | Valid Registration |
| Mode S Code | 51177700 |
| Mode S Code Hex | A4FFC0 |