In the previous clips the ETOPS rules were shortly discussed, which prohibit aircraft with only two engines from making certain Atlantic crossings. An example illustrating the need for this rule is Air Transat Flight 236, a flight from Toronto to Lisbon. Over the Atlantic ocean the Airbus A330 (shown below) experienced a fuel leak and subsequent double engine failure.

Question

Image courtesy of Abdallahh, CC - BY

Still 120 kilometres removed from the nearest airport (on the Azores), the A330's second engine failed at an altitude of 10 kilometres, causing the aircraft to lose electric and hydraulic power as well.

Eventually the aircraft made it to a military base on the Azores, for this exercise we estimate the aircraft reached the military base with 500 metres of 'spare' altitude. Assuming that there was no wind, what was the glide ratio of this A330?

Answer 1

The glide ratio of an aircraft is the distance it can travel horizontally divided by the height it descends vertically. To calculate the glide ratio for Air Transat Flight 236, we need to find the horizontal distance traveled and the vertical descent.

Given the problem, we have:

• Vertical descent: 10 kilometers (10,000 meters) altitude initially, and the aircraft had 500 meters of 'spare' altitude when reaching the military base. Therefore, the actual vertical descent is:

  \[ \text{Vertical descent} = 10,000 , \text{meters} - 500 , \text{meters} = 9,500 , \text{meters} \]

• Horizontal distance traveled: The problem states that the aircraft was 120 kilometers away from the nearest airport when the second engine failed. To convert kilometers to meters, we have:

  \[ \text{Horizontal distance} = 120 , \text{kilometers} = 120,000 , \text{meters} \]

Now, we can calculate the glide ratio as follows:

\[ \text{Glide Ratio} = \frac{\text{Horizontal Distance}}{\text{Vertical Descent}} = \frac{120,000 , \text{meters}}{9,500 , \text{meters}} \]

Calculating this gives:

\[ \text{Glide Ratio} \approx 12.63 \]

Thus, the glide ratio of the Airbus A330 in this scenario is approximately 12.63:1. This means that for every meter it descends, it travels about 12.63 meters forward horizontally.