The Pratt & Whitney 747SPs: the last 747SPs flying

A new engine has to fly before it is certified, and the safest way is to hang it on an aircraft with plenty of other engines. Pratt & Whitney Canada's 747SPs do that: a test engine replaces one of the four JT9Ds or sits on a separate stub pylon on the forward fuselage, with the cabin full of instrumentation racks and engineers instead of seats. The 747SP suits the job because it is strong, has a huge range and fuel load for long test sorties, and climbs higher than almost any airliner, which matters when the test is how an engine behaves at altitude, in icing or during a relight.

The geared turbofan that powers the A220, the A320neo and the E-Jet E2 did much of its early flying under a Pratt & Whitney 747SP wing, and the aircraft have carried everything from turboprops to the latest business-jet engines. Tests often run as long loops over Québec, the Maritimes and the North Atlantic, so a 747SP broadcasting out of Mirabel with no airline callsign is usually one of these.

C-FPAW began as a 747SP-J6 for CAAC, the Chinese state airline, and first flew on July 11, 1980; it flew for Air China as B-2452 until 1999, then for a United Arab Emirates operator, and joined Pratt & Whitney Canada in June 2009. C-GTFF is a 747SP-B5 built for Korean Air, acquired by Pratt earlier and used for the PW1000G program among others. Both wear Pratt & Whitney's blue-and-white scheme. Boeing built only 45 747SPs, and by 2026 one of these two was the only example reported in active service; the rest are stored or in museums, including the Iran Air aircraft that flew the type's last airline service in 2016.

The SP is a 747 that looks too short: the fuselage is 47 feet shorter than a 747-100, so the hump seems oversized and the tail is taller than on any other 747. Pratt's aircraft have few windows, a stub pylon on the right side of the forward fuselage that may or may not have an engine on it, and sometimes one engine under the wing that visibly does not match the other three. On the tracker they broadcast C-FPAW or C-GTFF with Pratt & Whitney callsigns, usually circling in test patterns rather than flying point to point.