You are predicting both the runway arrival time and the gate arrival time, so you have two predictions for each airplane.
Your predictions will be evaluated based on the
[root mean squared error (RMSE)](http://www.google.com/url?q=http%3A%2F%2Fen.wikipedia.org%2Fwiki%2FRoot-mean-square_deviation&sa=D&sntz=1&usg=AFQjCNFtMkTGCBKlH0AYo1LvBTwo5WP3oQ)
between the predicteds and the truth:
$$ \textrm{RMSE} = \sqrt{\frac{1}{n} \sum_{i=1}^{n} (y_i - \hat{y}_i)^2}$$
We will separately compute the RMSE for gate arrival times and runway arrival times, and use a weighted average of the two:
$$ \textrm{RMSE_Final} = (0.75 \times \textrm{RMSE_Gate}) + (0.25 \times \textrm{RMSE_Runway}) $$