For it to make sense, I think we first need to know why he's about to enter panic mode,did his last problem come about cos of the way he arrived at the airport. ...
Taxi can always not turn up on time, break down or crash....and when getting a taxi early, the driver could be coming off night shift and usually tired, twice I've had tired drivers nodding off ...
Bus,minivan, same, can even be stuck in traffic. ..
Metro and then express train, no problems, take a bit longer but for sure will get there on time.