To find the constant of proportionality in a proportional relationship, we can use the formula:
\[ k = \frac{y}{x} \]
where \( k \) is the constant of proportionality, \( y \) is the flight hours, and \( x \) is the hours charged.
From the provided data, we can choose any pair of \( (x, y) \) values since they all exhibit a proportional relationship. Let's take the first pair:
When \( x = 1 \), \( y = 1 \):
\[ k = \frac{1}{1} = 1 \]
Now let's check another pair for verification. Using \( x = 4 \), \( y = 4 \):
\[ k = \frac{4}{4} = 1 \]
Using \( x = 7 \), \( y = 7 \):
\[ k = \frac{7}{7} = 1 \]
Using \( x = 8 \), \( y = 8 \):
\[ k = \frac{8}{8} = 1 \]
In all cases, the constant of proportionality \( k \) is 1.
Therefore, the constant of proportionality is 1 flight hour per hour charged.