Why are fuel tanks strategically placed? What are fuel blocks?

With the development in engineering and technologies, all have evolved as such the aircraft’s design too. Some strategic points regarding the placement of the fuel tanks are:

1. For passenger safety, the fuel tanks are placed on the outer side of the fuselage.
2. At the time of an aviation failure, it helps in fuel dumping through the vent tanks.
3. Maintain the weight and balance of an aircraft is also very necessary, to make it stable the fuel tanks are placed in its wings. Keeping the fuel in its main body would disturb the center of gravity at takeoff and landing.
4. Also, the wings tend to bend upward due to an induced drag on its wings, to lower this thrust an extra weight of fuel is put on.
5. With a huge amount of oil, splashing is natural, to avoid this to a certain extent, tanks are divided into small blocks.
6. It provides more space to its passengers, luggage, etc.

Aviation fuel is put in an aircraft with precise calculation, these calculations follow certain orders called fuel blocks:

• Trip fuel: the fuel that is used for an ideal trip.
• Contingency fuel: this is an extra 5% of the trip fuel or five minutes of extra flight fuel, kept for unforeseen factors such as wind direction, atmospheric conditions, or route changes.
• Alternate fuel: this is to reach the nearest alternate airport, due to unavoidable circumstances in the destination airport.
• Taxi fuel: prior to the final takeoff and after landing, the aircraft taxi with its own engine power from the gate position to the runway, and vice-versa, this fuel gets in use.
• Extra fuel: if the pilot is familiar with the airport, he/ she may opt for extra fuel.
• Final Reserved fuel: this is the last left fuel in an aircraft, with a flight duration of 30 minutes, maintaining a height of 1,500 feet over the alternate airport. This is in use if the alternate airport ATC faces an issue clearing the runway.