Flight duration changes

I'm booked on VS077 in December and the other day received a notice that the flight times have changed. Does anyone know why a flight in July should take an hour less than the same flight in December?

It is likely they are expecting more delays in December so therefore they extend the duration so as not to look bad.
This happens all the time.
There are short haul routes in the UK that have 50% addoitional time from the shortest to longest depending on the time of day. and obviously the distance remains the same.

It is likely they are expecting more delays in December so therefore they extend the duration so as not to look bad.
This happens all the time.
There are short haul routes in the UK that have 50% addoitional time from the shortest to longest depending on the time of day. and obviously the distance remains the same.

Indeed. Happens everywhere - we flew EWR-CLE on CO in 2006 which was scheduled at 2 hours although the flight time was only 1 hour.

The other thing in the winter is that often there is more head wind going Westbound - our VS27 last Nov was 9:46 compared to a "normal" flight time of 8.5-9hrs on every previous LGW-MCO I have been on (summer).

arent the 330s also a bit 'slower' ?