Sneakernet Estimate: Data Throughput of a Jumbo Jet Hauling CDs Over the Atlantic

A Boeing 747 is loaded with compact discs and flies across the Atlantic Ocean. If you treat that flight as a way of moving data from one continent to the other, what is its bandwidth, in bits per second? Walk the interviewer through the equation you would use, the assumption behind each input, the arithmetic, and how you would check that the result is reasonable. ```hint Think of the plane as a moving hard drive The plane is a storage device in transit. What limits how much it can hold, and over what span of time does all of that data arrive? ``` ### Clarifying Questions - Is the 747 a stripped freighter whose whole main deck and lower holds can take discs, or a passenger aircraft with its seats and baggage still in place? - Should the plane be packed to the ceiling, or loaded only up to the weight it can carry and still take off? - Are these standard data CDs rather than DVDs or Blu-ray discs, and are they bare on spindles or in jewel cases? - Which crossing, and does the clock cover only the flight or the whole trip, including loading and reading the discs at the far end? ### What a Strong Answer Covers - An equation that ties together the number of discs, the data per disc and the transit time, with bandwidth defined as data delivered per second. - Labeled, rounded assumptions for the usable space or payload, the size and weight of a disc, its capacity and the flight time. - Careful unit handling from megabytes to bits and from hours to seconds. - A sanity check on the physical limits of the load and a comparison with a familiar network link. - A clear distinction between throughput and latency, including the overhead of writing and reading the discs. ### Follow-up Questions - Swap the CDs for hard drives or microSD cards. How does the estimate change, and which limit binds now? - If the clock also covers burning the data onto the discs and reading it back after landing, what effective throughput would you report? - When would a company rationally ship physical storage instead of sending data over the network, and what would drive that decision?