More than 10,000 flights were delayed or cancelled, accounting for 13.5%.
The national flag carrier Vietnam Airlines and budget Vietjet Air recorded fewer delayed and cancelled flights, down 1.4% and 3.9% year-on-year, respectively.
Meanwhile, Jetstar Pacific and Vasco saw increases in delayed and cancelled flights.
Specifically, Vietnam Airlines ran 32,504 flights, 29,321 of which were punctual, equivalent to 90.2%.
During the period, Vietjet Air and Jetstar Pacific operated 29,261 and 8,985 flights, with their rates of delayed and cancelled flights being 16.6% and 21.1%, respectively.
Vasco recorded the highest number of punctual flights, equivalent to 97.7% out of 3.415 flights.
The CAAV attributed flight unpunctuality to late arrival of planes and subjective reasons from airlines, as well as weather conditions and flight management.
Also according to the CAAV, Vietjet Air saw the highest increase in flights by 26.6%, followed by Vasco (23.2%), Jetstar Pacific (10.9%) and Vietnam Airlines (3.9%).