Something like that yes, but again, the arrival time is calculated as the time the a/c blocks on. However, I was refering to the average passenger's perception of running late being based on the take-off time.
As a crew member for another airline, I am well accustomed to chocks time.. and they were still late every time.
Indeed, on most occasions, boarding only started a few minutes prior to planned off blocks time, and whilst arrival was usually back on schedule, the passenger experience of sitting in an airport prior to departure at horrible times of the day with no information is pretty disappointing and is a sure way of loosing clients, even if the OTP would be calculated by arrival times.
The customer service was always pretty poor too and it really became a last resort option for me, which is a shame, as it was by far the most convenient connection which should speak volumes.