It's all to do with wind. When you're flying from east to west, the plane is fighting strong westerly winds, or jet streams, which can be more than 150 knots.
These high-altitude winds always blow from the west to the east, over the Atlantic. As a result, a plane travelling towards India from New Zealand will be slowed down by these headwinds, but will benefit from tailwinds on return.
What is the best fabric to fly in?
Dress in layers - especially when you're travelling to a dramatically different climate. Think cotton scarfs or wraps, sweatshirts, cardigans or light jackets. Make sure you're wearing breathable fabricssuch as cotton, silk or linen. Fabrics that don't allow air circulation keep sweat on the skin and you'll feel grimy upon landing.
Keep clothes loose-fitting, as you're at greater risk of developing deep-vein thrombosis. Also consider compression socks for the same reason - particularly if you're pregnant, flying longhaul, or have a medical condition. And of course, make sure that you're wearing comfortable shoes - travellers end up on their feet a lot. However, don't feel like dressing in comfort means you have to sacrifice style, and always consider adding a touch of glamour to your in-flight ensemble as a throwback to the days when flying was a special occasion.
A friend and I travelled through the US in 2014 using money loaded on to a Cash Passport card from the bank. It mostly worked well, though the card had a few glitches - sometimes it would double charge, sometimes it refused to work, and sometimes places just wouldn't recognise it. We're embarking on a similar trip this year, and I wonder whether it might be better to just load a spare credit card and use it in the same way. I know the currency rates will fluctuate but wondered if it is more or less the same thing.
I asked Kate Sluka of Consumer magazine for help with this one - she says it pays to think about the places you plan to use the card and be aware of hidden fees. Although Cash Passport has no fee, ATM providers can still charge one. Also, some businesses do not accept preloaded debit cards, which is effectively what these travel cards are.
"Also, be aware hotels or rental cars, or even at some gas stations, preauthorisation holds can be put on the card," she says. Until the holds are released, you won't be able to access the money.
It's probably a good idea to take spare credit card with funds loaded on to it, as well as the travel card.
However, Sluka also says to be wary of retailers offering to charge in New Zealand dollars. Called a "dynamic currency conversion", the associated conversion fees can be more expensive than the card scheme's fee. Be sure to ask what the fee is and if it's higher, or they won't disclose, ask to have the card charged in the local currency.
Tweet us @NZHTravel or use the hashtag #NZHAskAway
Email your questions to email@example.com