Hi sm001,
1. If you are buying directly from the Airline's online system or from their website, I think it is OK.
2. If you are buying from third party, than you have to be very careful, there are many online scams now days.
3. You may call the airline office and check if they have given authorization to third party to sale their tickets online
Sometime third party website will take you directly to the Airline's booking server / website (in this case it is also OK)
These tips may be helps full for everyone:
Don't be grounded by flight booking scams
1. Travellers should check the authenticity of flight booking websites before making any reservations for domestic and international travel.
2. These fake traders claim to sell tickets on behalf of well-known airlines, when in fact the airlines have not authorised the sale.
3. After purchasing the fake tickets, victims are given a booking number but when they go to use this number they find that the booking doesn't actually exist with the airline they are supposed to be travelling on.
4. Consumers may be contacted directly by fraudulent traders, or may follow links via popular social networking sites.
5. Some victims have lost in excess of $1000 for fake international flight bookings, while others report instances of identity theft after interactions with the fake trader.
Warning signs:
1. The flight booking website is not well-known, or you have never heard of it before.
2. The website claims to offer flights at unusually cheap prices, some up to 50% off.
3. There is no proper local contact number or address for the trader, often because they are not located in your area.
4. The site does not have a valid membership number or registration.
Protect yourself:
1. Be cautious when considering whether to purchase really cheap airfares – if it looks too good to be true it probably is.
2. NEVER send money or give personal details to people you don't know and trust.
3. If you think you have provided your account details to a scammer, contact your bank or financial institution immediately.
Hope that helps,
hmisabpk