| Tail Number / N-Number | N421ST |
| Manufacturer | CESSNA |
| Model | 421C |
| Year Built | 1976 |
| Manufacturer's Serial Number | 421C0114 |
| Aircraft Type | Fixed wing multi engine |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 8 seats |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Engine Manufacturer | CONT MOTOR |
| Engine Model | GTSI0-520-F-K |
| Engine Type | Reciprocating |
| Number of Engines | 2 engines |
| Horsepower per Engine | 435 hp (325 kW) |
| Total Horsepower | 870 hp (649 kW) |
| Average Cruising Speed | 90 miles per hour |
| Type of Registrant | LLC |
| Owner Name | PONDEROSA AIR LLC |
| Street | 7110 REPUBLIC AIRPORT |
| City | FARMINGDALE |
| State | NY |
| Zip Code | 11735-3954 |
| Region | Eastern |
| County | Nassau County |
| Country | US |
| Fractional Ownership | No |
| Airworthiness Classification | Standard |
| Airworthiness Date | 1976-06-11 |
| Certificate Issue Date | 2011-09-14 |
| Last Action Date | 2022-09-23 |
| Expiration Date | 2027-09-30 |
| Status | Valid Registration |
| Mode S Code | 51200370 |
| Mode S Code Hex | A500F8 |
Deregistered Aircraft 1 of 1. This aircraft was previously assigned the N-number N421ST.
| Tail Number / N-Number | N421ST |
| Manufacturer | CESSNA |
| Model | 421A |
| Manufacturer's Serial Number | 421A0119 |
| Aircraft Type | Fixed wing multi engine |
| Category | Land |
| Builder Certification | Type Certificated |
| Number of Seats | 7 seats |
| Weight Class | CLASS 1 (Up to 12,499 pounds gross take off weight) |
| Number of Engines | 2 engines |
| Average Cruising Speed | 172 miles per hour |
| County | Nassau County |
| Last Status | N-Number Assigned – but has not yet been registered |
| Cancellation Date | 1990-04-11 |