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Illustration of a Baseline Citation S/II design. Not a photo of N633AT.
Illustration of the Baseline Citation S/II design, not a photo of N633AT. Baseline S550 Citation S/II exterior design reference. Installed conversions, radomes, paint and equipment vary. This illustration does not establish the installed engine, cabin or aircraft performance.

N633AT 1985 Cessna S550 (design reference)

Serial number S550-0066. Registered to NRX Pharmaceuticals Inc, Wilmington, DE, US.

  • 1985Built
Cessna S550 (design reference): specs, US fleet and every tail number

INSIDE

The Citation S/II seven-chair example cabin.

Illustrations of a representative Citation S/II seven-chair example cabin, not N633AT’s. Every aircraft’s completion differs. Baseline S550 Citation S/II exterior design reference. Installed conversions, radomes, paint and equipment vary. This illustration does not establish the installed engine, cabin or aircraft performance. Explore the Cessna S550 (design reference) interior and layout. Cessna S550 (design reference) interior: cabin size and seat map.

Citation S/II seven-chair example. Illustrative interior, not a photograph of this aircraft.
A representative Citation S/II seven-chair example cabin.
Top-down view of a Citation S/II seven-chair example cabin. Seven main-cabin chairs. Lavatory excluded from the illustrated count. Actual layout and equipment vary.
Seven main-cabin chairs. Lavatory excluded from the illustrated count. Actual layout and equipment vary.

SPECIFICATIONS

Cessna S550 (design reference) specs

Published figures for the type, from public sources. A given aircraft varies with its completion, weight and mods.

Full Cessna S550 (design reference) specs, range and cabin

Model
Cessna S550 (design reference)
Year
1985
Serial number
S550-0066
Engines
2 engines

THE AIRCRAFT’S LIFE

N633AT, from delivery to today.

Registration events from FAA records, compiled October 2026. Maintenance, damage and component history live in the logbooks, not the registry.

  1. Registry record

    Airworthiness date on the current FAA record (standard category).

    FAA registry

  2. Registry record

    Earlier use of the number: N633AT was assigned to another aircraft, a Cessna 500. That registration was cancelled on this date.

    FAA registry

  3. NRX Pharmaceuticals Inc

    Certificate of registration issued as N633AT.

    FAA registry

FAA REGISTRATION

Registration details

Registration
N633AT
Status
Current as of October 2026
Certificate issued
Sep 9, 2026
Airworthiness date
Sep 19, 1985
Last FAA action
Sep 9, 2026
Registration expires
Sep 30, 2033
Mode S code (hex)
A848F3
Aircraft category
Light jet
Weight class
Under 12,500lbs

From FAA registry data as of October 2026. Check the FAA registry for the current record.

OWNERSHIP

Registered owner

NRX Pharmaceuticals Inc

Corporation · Wilmington, DE, US

ESTIMATED VALUE

What N633AT might be worth

No type-level range

This aircraft is classified as a jet, but its engine type and thrust are not established. Radar cannot calculate a supported value range. Total time, condition, equipment and the completeness of the logbooks set what one is worth.

Open the aircraft value tool

SOURCES

Where this page comes from

Built from FAA registry records, manufacturer specifications, and public flight-tracking and market data, compiled October 2026. Values come from Radar’s aircraft value model. Owners and operators can ask for a correction or removal.

BUYING, SELLING OR FINANCING

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