The option of travelling by air to domestic destinations is well within the reach of the middle class, especially after national and private domestic carriers introduced the advance purchase excursion (Apex) fare several months ago.

Last year, when the airline industry was bearing the brunt of empty planes, wasted perishable seats and falling revenues, Apex fare was introduced by both Indian Airlines and Jet Airways.

At the same time, Air Sahara introduced the online auction system in order to lure first class train travellers to shift to airlines as a cheap, convenient and faster way to travel.

You can now also save money by planning your trip in advance or participating in an online auction for airline tickets.

What is an advance purchase excursion fare? It's not really a discount in the sense that if you book today to fly tomorrow you will have to pay the normal fare.

The Apex fare structure gives you a benefit of booking in advance and getting a better deal. Internationally, airlines offer huge discounts if you book say six months or three months in advance.

In India, however, we have 30-day, 21-day, 15-day and 7-day Apex schemes for Jet Airways and Indian Airlines.

If you book online through an auction you need to start bidding for Indian Airlines tickets seven days or 21 days before the day you wish to fly.

For instance, the way the 7-day auction works is that the bids start 12 days in advance, while the auction ends eight days before the flight.

Effectively, your ticket is booked seven days in advance. Indian Airlines also offers Apex tickets which you can book at the airline office or through an agent.

Similarly, Air Sahara's auctions begin 24 days prior to departure and end 15 days before departure.

Under the online auction method, an air ticket for an Indian Airlines Delhi-Goa sector could come for as less as Rs 5,380 (the minimum bid price) or a New Delhi-Mumbai Sahara flight will make your pocket lighter by only Rs 2,775 (again the minimum bid price).

Compared with that Jet Airways' 30-day Apex fare for, say, a Mumbai-Chennai flight will cost you Rs 2,300. Similarly, the Mumbai-New Delhi fare works out to Rs 3,400.

This 30-day scheme is valid only up to November 15, 2003.

If you book 15 days in advance, the fare will work out to Rs 3,480 for Mumbai-Chennai and Rs 4,180 for Mumbai-New Delhi.

Remember, that cancellations are extremely expensive on the Apex fares.

Some airlines do not allow it or you may end up losing more than 50 per cent of the money you paid.

Also remember that under the Apex fare structure you cannot change the flight timing or date of travel.

Indian Airlines does not allow bidding for more than two tickets, while Sahara Airlines does not offer auctions for all flights on all sectors.