References 579% CONFIDENCEOverall confidence: 79%How well the pin's source and references back up its dates.Weighted average of how firmly 5 references, the source included, support the pin's start and end times; a reference counts half as much for every 180 days older than the newestShow all pins at 75% confidence or better

The first entry is always the pin's source. Overall confidence is a weighted average of how firmly each reference supports the start and end times used above; a reference counts half as much for every 180 days older than the newest.

• [1]90%
  airwaysmag.com/new-post/prototype-boeing-747-400-flight

  airwaysmag.com· Posted Oct 23, 2026· Starts Apr 29, 1988 ✓· 37% of score

  Airways: "Today, in 1988, the world's first Boeing^[4] 747-400, registration N401PW, took to the skies for the first time. The jet ... departed Paine Field (PAE) under the command of test pilot James Loesch and co-pilot Kenneth Higgins."

• [2]70%
  Boeing 747-400 - Wikipedia

  en.wikipedia.org· Added Oct 23, 2026· 37% of score

  Gives first flight 29 April 1988, certification 9 January 1989, entry into service 9 February 1989 and the specification table.^[1]

• [3]75%
  N401PW - This Day in Aviation

  thisdayinaviation.com· Published Jun 27, 2026· 23% of score

  Records the first 747-400 N401PW's 27 June 1988 Moses Lake test flight and FAI record.^[1]

• [4]85%
  747 Airplane Characteristics for Airport Planning (D6-58326-1 Rev F) - Boeing

  boeing.com· Published Dec 1, 2024· 3% of score

  Boeing's manual gives the 747-400's typical 400-seat layout and maximum takeoff weights.

• [5]70%
  The world's first 747-400 on its last legs - AirlineGeeks

  airlinegeeks.com· Published Sep 8, 2015· 0% of score

  Says the aircraft first flew on 29 April 1988 as N401PW and became Northwest's N661US.^[1]

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