Fermi Estimation Case: How Heavy Is a Boeing 747?

Estimate how much a Boeing 747 weighs. Walk through how you get to the number, call out each assumption, and finish with a figure and how confident you are in it. ```hint Break it into parts Split the aircraft into a handful of large pieces whose sizes you can picture, and settle early whether fuel, passengers and cargo belong in the number. ``` ### Clarifying Questions - Do you want the empty aircraft, or the aircraft loaded with fuel, passengers and cargo at takeoff? - Which 747: an early passenger model, a later one, or a freighter? - Should the answer be in kilograms, pounds or tonnes, and how precise does it need to be? ### What a Strong Answer Covers - A settled definition of which weight is being estimated, agreed before any arithmetic - A breakdown into components that together account for the aircraft's mass - Labeled, physically sensible assumptions for each component, including the sizes and material density used - Arithmetic that is correct and unit-consistent - A sanity check from an independent angle, a final range, and the inputs that move the answer most ### Follow-up Questions - If you could not look the number up, how would you measure it directly? - Which part of your estimate are you least confident in, and how would you narrow it? - How does the takeoff weight differ between a long-haul flight and a short one?