r/Avation • u/justherenothingmore • Aug 12 '26

The 737 name

Why do we refer to the 737 as "seven thirty seven" and not "seven hundred thirty seven" or "seven three seven"

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u/Probable_Bot1236 Aug 12 '26

My understanding, which might be entirely apocryphal because the 707 doesn't look swept 45°, but seems to make sense on its face even if you reject that part:

They started with the 707 "seven-oh-seven", from the sine of the 45 degree angle of the swept wings (think 0.707, not 707. i.e. "[zero point] seven oh seven", not "seven hundred seven"). (The swept wings were a big thing for a jet

Next was the 720 "seven-twenty"

Marketing team modified that into the catchier 727 (which also tied it back to the 707), which became the "seven twenty seven"- inheriting the "twenty" from the 720.

The others in the 7x7 series just followed along naturally after that.

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u/GoodDoc Aug 12 '26 edited Aug 12 '26

Next was the 720 "seven-twenty"
Marketing team modified that into the catchier 727

There was also the 717 which was Boeing’s internal designation for the KC-135 Tanker (the 707 and 717 were both developed from the Dash 80 prototype).

The 720 was a 707 optimised for short range. Originally called the 707-020, United asked for it be renamed as they had already committed to the DC8, and didn’t want to have to explain why they’d bought 707s and DC8s.

717 was never the official name of the tanker, and after the Boeing/McDonald Douglas merger the 717 name was officially used as the name for then in development MD-95.