Boeing 747-400 Takeoff Speed: What You Need to Know

  • Context: Boeing 
  • Thread starter Thread starter Badass
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Discussion Overview

The discussion revolves around the takeoff speed of the Boeing 747-400, exploring factors that influence this speed such as weight, weather conditions, and air density. Participants share insights based on personal experiences and technical knowledge related to aviation.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant inquires about the takeoff speed of the 747-400, noting variability due to weather conditions.
  • Another participant states that the takeoff speed is approximately 250 kph (135 KIAS).
  • It is mentioned that the takeoff speed increases with the aircraft's weight, implying a relationship between weight and required speed for lift.
  • A participant references an average takeoff speed for a fully-loaded passenger carrier, citing Air New Zealand as a source.
  • Discussion includes the importance of the Pilot Operating Handbook (POH) for determining specific takeoff speeds based on conditions.
  • Weather conditions and air density are highlighted as significant factors affecting takeoff speed, with a note that hot air can extend the takeoff roll.
  • A participant points out that pilots rely on dynamic air pressure readings for rotation, which may not directly reflect changes in air density.
  • There is a mention of a term related to aviation that one participant is unfamiliar with, indicating a potential gap in knowledge or terminology among participants.

Areas of Agreement / Disagreement

Participants generally agree that takeoff speed is influenced by multiple factors, including weight and weather conditions. However, there are differing views on the specifics of how these factors interact and the terminology used, indicating that the discussion remains somewhat unresolved.

Contextual Notes

Participants acknowledge that the takeoff speed can vary significantly based on specific conditions, but do not provide a definitive formula or consensus on exact speeds under varying circumstances.

Badass
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Does anyone know what speed of take off the 747-400 achieves please? I do know that it differs a bit due to weather conditions but since I've been on them so many times I was getting rather interested.:confused:
 
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Hi, Badass;
The 747-400 lifts off at 250kph.
 
Whilst 135 KIAS (250 Kph) sounds reasonable, the planes that I flew had also a weight factor. The heavier weight, the higher the T/O speed.
 
Correct of course, Andre. More speed for more lift to overcome more gravity. I was quoting what I assume to be an average for a fully-loaded passenger carrier taken from the Air New Zealand website.
 
The POH is going to tell you what the rotate speed is based on weather and loading. Does anyone happen to have a operations manual for a -400?
 
Glad you mentioned the weather, Fred. I forgot to also clarify that the speed depends upon air density as well as weight. It takes a lot longer to get off the ground in hot air.
 
Don't forget the nasty, three H's Danger...
 
speed depends upon air density.

True, but the pilot won't notice because he is actualy looking at the dynamic air pressure and he is supposed to rotate when the dial hits the mark which is independent of the air density. The actual groundspeed will change though and hence the T/O roll.
 
FredGarvin said:
Don't forget the nasty, three H's Danger...
Maybe things have changed more than I realized in the 29 years since I last had my mitts on a yoke. I've never heard that term.:confused:

To Andre: Once again correct, from a pilot's perspective. Badass, however, is obviously not one, so I assumed (yeah, bad habit) that he was referring to ground speed.
 

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